2014 Chemistry - Cssa Trial With Solutions 5q266z

Centre Number

CSSA

Student Number

CATHOLIC SECONDARY SCHOOLS ASSOCIATION OF NSW

2014 TRIAL HIGHER SCHOOL CERTIFICATE EXAMINATION

Chemistry Morning Session Friday 1 August 2014

General Instructions • • •

Reading time - 5 minutes Working time- 3 hours Write using black or blue pen Black pen is preferred • Board-approved calculators may be used • Draw diagrams using pencil • A data sheet and Periodic Table are provided SEP ARATEL Y • Write your Centre Number and Student Number on the top of this page and page 13

Total marks- 100 [ Section I ]

Pages 2-31

75 marks This section has two parts, Part A and Part B Part A - 20 marks • Attempt Questions 1-20 • Allow about 35 minutes for this section Part B- 55 marks • Attempt Questions 21-33 • Allow about 1 hour and 40 minutes for this section

[Section II

Pages 33-40

25 marks • Attempt ONE question from Questions 34-38 • Allow about 45 minutes for this section

Disclaimer Every effort has been made to prepare these 'Trial' Higher School Certificate Examinations in accordance with the NSW Board of Studies documents, Principles for Setting HSC Examinations in a Standards-Referenced Framework (www.boardofstudies.nsw.edu.aui.. Jorincioles-for-setlina-exams.htmll, and Principles for Developing Marking Guidelines Examinations in a Standards Referenced Framework ('.'Avw.boardofstudies.nsw.edu.aulmanualsforincioles hsc.htmll. No guarantee or warranty is made or implied that the 'Trial' Examination papers mirror in every respect the actual HSC Examination question paper in any or all courses to be examined. These papers do not constitute 'advice' nor can they be construed as authoritative interpretations of Board of Studies intentions. The CSSA accepts no liabili1y for any reliance use or purpose related b these 'Trial' question papers. Advice on HSC examination issues is only to be obtained from the NSWBOS.

3800-1

Section I 75 marks Part A- 20 marks Attempt Questions 1-20 Allow about 35 minutes for this part

Use the multiple-choice answer sheet for Questions 1-20.

1

Ethanol can be converted to ethylene using which reaction and catalyst below? (A) Addition with a dilute sulfuric acid catalyst (B)

Substitution with a dilute sulfuric acid catalyst

(C)

Hydration with a concentrated sulfuric acid catalyst

(D) Dehydration with a concentrated sulfuric acid catalyst

2

Identify the reaction that shows the catalytic cracking of decane to form ethylene and hexane. (A) C10H22(l) --+ CzH4(g) + C6H14(1) (B)

C10Hzz(l) -> 2CzH4(g) + C6H14(1)

(C)

C10Hzz(l) --+ 2CzH4(g) + C6H1z(l)

(D) C10Hzz(l) --+ CzH4(g) + C6H16(1)

3

Which set of isotopes contains only stable nuclei?

c

(A)

1~

(B)

IH

(C)

2

(D)

39K 19

~i Pb

1~ 0

jH

c

238 u

1~

i3 Ca 12 c 6

92

~§ Tc 1~ 0

2

4

The reaction below shows the ionisation of hydrogen fluoride in water.

IdentifY the acid I conjugate base pair.

(A) HzO I H10+

(B) HF IF" (C) HF IHzO (D) H10+ IF

5

An ice core is a cylinder-shaped sample of ice drilled from a glacier. Ice core records provide the most direct and detailed way to investigate past climate atmospheric conditions and atmospheric gas concentrations. Air trapped in glacial ice offers a means of reconstructing variations in the concentrations of atmospheric gases over time scales ranging from the last 200 years to the last few hundred thousand years. Analysis of ice core samples is generally undertaken by teams of scientists, many of whom are chemists. Which ofthe following is the LEAST likely reason for having chemists collaborate on projects like this?

6

(A)

Chemists specialise early in their careers and tend to develop expert knowledge and skills in highly specific areas.

(B)

Bringing varied knowledge and skills together from different chemists will ensure that the quality of the investigation is enhanced.

(C)

Projects involving a number of chemists with different knowledge and skills tend to cost less than having one chemist complete the project on their own.

(D)

A team of chemists with different knowledge and skills will complete an investigation in a shorter timeframe than one chemist working on their own.

Which of the following lists shows the compounds in order of decreasing boiling point? (A)

ethanol> ethane> ethanoic acid

(B)

ethane > ethanol> ethanoic acid

(C)

ethanoic acid > ethanol > ethane

(D)

ethanoic acid> ethane> ethanol 3

7

Polyhydroxyalkanoates (PHAs) are often called bacterial plastics because they are made using genetically modified bacteria. One widely manufactured and used polyhydroxyalkanoate is PHBV. PHBV is a condensation polymer with the repeating section of the structure shown below. CH2CH3

r H I r H o-c-c-c-o-c-c-c f~ I

I

I

I

H

H

H

H

n

Which two monomers are used to make PHBV? (A)

H

OHH

H

0

I

I

I

II

I

H-e -c -c-c-c -oH

(B)

I

I

I

I

H

H

H

H

H

H

I

H

I

H

I

I

I

I

(C)

I

H

H-

0

I

I

I

I

II

c- c -c- c-c -OH I

I

I

I

H

H

H

H

H

H

0

II

I

I

I

II

H - c - c - c - c -oH

I

H

0

I

I

I

II

I

I

I

H

H

H

H

OH

H

I

H

H

OH

H

4

H

H

OHH

0

I

I

I

II

I

H - C - C - C - C - C -OH

I

0

I

H

H

I

H

I I I II c -c- c-c -oH I I I H

H

I

H

H

H

H

H

H-C-C-C-C-OH

(D)

H

0

HO-C - C -C-C-C-OH H

H-

H

I

H

I

H

H

H

OH

H

0

I

I

I

II

HO-C-C-C-C -OH

I

I

I

H

H

H

8

An electrochemical cell was constructed using a magnesium anode and a platinum cathode. The cell potential was measured to be 3.8 V. Which of the following would be a suitable electrolyte for the cathode half-cell? (A) Hydrochloric acid

9

(B)

Magnesium nitrate

(C)

Platinum iodide

(D)

Potassium nitrate

An experiment was performed to determine the volume of carbon dioxide gas released during the fermentation of a glucose solution. The reaction took place over several days in a flask containing yeast that was immersed in a water bath at 28°C and stoppered with cotton wool.

Which of the following factors would most significantly compromise the validity of this experiment? (A) The evaporation of water (B)

The temperature of the water bath

(C)

Measurement error associated with determining the mass lost

(D)

The lack of oxygen due to the presence of the cotton wool plug

5

10 The equilibrium that exists between carbon dioxide gas at the top of a sealed bottle of soft drink and the carbon dioxide in aqueous solution is represented by the equation below. COz(g) ~ COz(aq) L'.H = -19.4 kJ mo1" 1

Which factor will increase the solubility of carbon dioxide in the solution? (A) Opening the lid (B)

Increasing the temperature of the system

(C)

Adding a catalyst to speed up the reaction

(D) Pumping more carbon dioxide into the space between the soft drink and the lid

11

Which of the following species is amphiprotic? (A) NHt

(B) HC03 (C)

H30+

(D) OR

12 Esterification is carried out using a method called refluxing. The main purpose of using reflux is to (A) provide a catalyst to speed up the rate of reaction. (B)

decrease the concentration of water in the mixture.

(C)

heat the reaction vessel without the loss of volatile reactants and products.

(D) increase the pressure of the system to shift the equilibrium toward the products.

6

13 A student tested a colourless solution that was known to contain a soluble salt of a polyatomic anion. She added the reagents to fresh samples of the solution in the order shown in the results table below. Reagent

Result

Add barium nitrate

White precipitate forms

Add sodium nitrate

No change

Add lead nitrate

White precipitate forms

Any conclusion about the identity of the salt from these results alone would be invalid because (A) many precipitates are white in colour. (B)

the reagents were added in the incotTect order.

(C)

the solubility of salts is dependent on temperature.

(D) she used a fresh sample of solution for each reagent.

14 A CFC was analysed using high-resolution mass spectrometry and was found to have the composition shown in the table below. Element

Molar mass (g mot1)

Carbon

24.10

Chlorine

106.25

Fluorine

56.95

Which of the following is an isomer of this CFC? (A)

1,1,2-trichloro-1 ,2,2-trifluoroethane

(B)

1,1 ,2-trichloro-1 ,2,2-trifluoropropane

(C)

1,1 ,2,2-tetrachloro-1 ,2-difluoroethane

(D)

1,1 ,2,2-tetrachloro-1 ,2-difluoropropane

7

15 The following graph represents the average annual concentration of two common gases over Mmmt Popa in Burma over a 22 year period. 50 45 40 ~

..c

c. 35 c. c 30

-

r- -

1-- -

-

·- -

"

0

·;;

..."'c

.

~

u

25 20

c 0

u

15

-- -- --

10 5

- f--

/

/

/

1\

/

/'

-- r----,,

/

/

""

;::--.. 1-- ,,

/

1978 1980 1982

Nb. /

1-

~

~~.......

f=

--r:::: X --i-

1984 1986 1988 1990 1992

/ /

r--

,r'

v

1994 1996

/

I

I

/ s ')2

1998 2000

Year

The sudden increase in the sulfur dioxide concentration in 1991 was most likely caused by (A) volcanic eruptions. (B)

an increase in lightning strikes.

(C)

a new power plant being opened in the area.

(D)

ozone layer depletion in the stratosphere over the area.

16 The pH of a nitric acid solution is 5.0 and its concentration is X mol 1'1•

If a hydrochloric acid solution had a pH of3.6, what would be its concentration? (A)

2X mol 1' 1

(B)

5Xmol 1'1

(C)

10Xmol 1'1

1 (D) 25XmolL'

8

17 In Australia, the purification and sanitation of water supplies generally involves the following four steps: 1. 2. 3. 4.

Screening Flocculation Filtration Disinfection

Some other countries use membrane filtration to assist in water treatment. There are three different types of filtration possible using membrane filters with the properties shown in the table below.

Filtration Technique

Pore Diameter (nm)

Removes

microfiltration

100-10 000

suspended solids, protozoans and bacteria

ultrafiltration

10- 100

viruses and large molecules

nanofiltration

I - 10

some heavy metal ions and small molecules

Which filtration techniques would be most suitable to replace steps 3 and 4 above in water treatment?

Step3

Step 4

(A)

microfiltration

micro filtration

(B)

nanofiltration

micro filtration

(C)

ultrafiltration

nanofiltration

(D)

nanofiltration

nanofiltration

9

18 A student was given 35 g of glucose to perform an anaerobic fermentation reaction in a flask where the carbon dioxide produced was able to escape. The graph below shows the change in mass of the reaction vessel over seven days. 382 380 ~

OL

~

~

...

~ ~

37H

= 376 0

"''~"' 374 ....'"'

.;;:"

~ 372

370

368 0

2

4

3

5

7

Time (days)

The mass of the reaction vessel becomes constant after Day 6 because (A)

all of the glucose has been used up in the reaction.

(B)

the fermentation reaction has reached equilibrium.

(C)

the ethanol concentration is too high and the yeast have died.

(D) the carbonic acid produced from the dissolution of carbon dioxide in water lowers the pH and kills the yeast.

10

19

Ammonia is synthesised from gaseous nitrogen and hydrogen according the following equation.

The graph below shows the relationship between the kinetic energy of the molecules and the relative number of molecules with those kinetic energies for a sealed container of hydrogen, nitrogen and ammonia at 298 K.

___:_1I___ ,-----.1298

--

r

--

''

,'

I\-

:

I -.

.'

I

-- .

I

~- --1-I

?~-= ~- 0-:J :

·-

\\.CJ_______

--.·- - -

i

I

I I

I

I

~~ll

'

--

i

------+------

'

I -----·

Kinetic Energy U)

The activation energy (Ea) refers to the minimum kinetic energy needed for molecules to have a successful collision and a reaction to occur. Which of the graphs below correctly represents the relationship between kinetic energy and temperature for this system at a higher rate of reaction than that shown in the graph above? (A)

.,••

(B)

••-····-._298

0

•

! .

" 0

0

z

•>

,\ .......

!l

······

~

0

0

....

z

•>

.....

_

.."

·::;;

·--~

! '/

'

_298 K

-

0

•

0

! ---

0

•

."

f l\

li

.

.

-· ····--·

.._29 K

\ ,..

---

- -

--

/i

---

i" \

'\

"I?-'-~ ' ' '-....:::::_,.. i'lcreased ieactiOn rate-=::, :

-

1"..:: \.:.:

.... ---

!

!

i

-------

.....

-

·····-

I

E. Kinetic Energy

OJ

Kinetic Energy U)

11

..

~--

'i

(D)

,

- --

-

-

\ '

z

·~

v-··

Kinetic Energy U)

---

i-- v---- ---• .-

~

0

-·

E.

.,•• "

-·-·-

"

"" "'"' rate

Kinetic Energy U)

(C)

0

•

A

V/

~

.."'

----

0

0

''iii

.,.•

'

••

20

Ozone concentrations are measured in Dobson units. Dobson units (DU) are the standard way to express ozone concentration in the stratosphere. A concentration of one DU means 20 that there would be 2. 7 x I 0 ozone molecules in a layer of air that was one square metre in area and 0.01 mm thick. A baseline value of220 DU is chosen as the starting point for an ozone hole in the stratosphere since total ozone values of less than 220 Dobson units were not found in historic observations over Antarctica prior to 1979. Which of the following concentrations, in moles per cubic metre (mol m·\ is most nearly equivalent to 220 Dobson units? (A)

0.05 mol m· 3

(B)

10 mol m·3

(C)

5,000 mol m-3

(D)

10,000 mol m-3

12

-!1/

CATHOLIC SECONDARY SCHOOLS ASSOCIATION OF NSW 2014 TRIAL HIGH SCHOOL CERTIFICATE EXAMINATION

CSSA

Centre Number

Chemistry Student Number

Section I (continued) Part B- 55 marks Attempt Questions 21-33 Allow about 1 hour and 40 minutes for this part

Answer the questions in the spaces provided. These spaces provide guidance for the expected length of response. Show all relevant working in questions involving calculations.

Question 21 (3 marks) Bond energy is the energy needed to break the chemical bond between two atoms. The bond energies for each of the two allotropes of oxygen are shown in the table.

j

Bond energy (kJ mor 1)

Oxygen (O:J

Ozone (03)

498

364

3

for the difference in bond energy for these two allotropes of oxygen.

13

3800-1

Question 22 (3 marks) Radioisotopes are used in industry and medicine. Using the table below or otherwise, identifY a radioisotope used in one of these fields and relate its use to its properties. Radioisotope

Radiation emitted

Half life

americium-241

alpha, beta

432.6 years

cobalt-60

beta, gamma

5.27 years

caesium-137

beta, gamma

30 years

tritium (Hydrogen-3)

beta

12 years

technetium-99m

gamma

6 hours

iodine-123

beta, gamma

13.2 hours

iodine-131

beta, gamma

8 days

14

3

Question 23 (4 marks) Describe the chemical and physical processes involved in the production of ONE of the following polymers from a natural, raw material, including any relevant chemical equations. • • •

polyethylene polyvinyl chloride polystyrene

15

4

Question 24 (3 marks) A student used the equipment below to determine the molar heat of combustion of ethanol.

f-.-----water

/I I ''

l ''

/

\ I

i\

I

)1

'• ...

• ...

'

spirit burner

The following data were recorded for the experiment. Mass of water

250.0 g

Initial temperature of water

17.5°C

Final temperature of water

47.5°C

Initial mass of spirit burner and ethanol

137.15 g

Final mass of spirit burner and ethanol

135.14 g

Calculate the molar heat of combustion of ethanol from the results of this experiment.

16

3

Question 25 (4 marks)

The diagram below shows a galvanic cell set-up under standard conditions.

salt bridge

Zn metal strip

Cu metal strip

Zn(N0 3)2 solution

Cu(N0 3)2 solution

colourless

blue

(a)

On the diagram, label the anode, cathode and direction of electron flow.

1

(b)

Write a balanced, net ionic equation for the overall cell reaction.

1

(c)

Identify and for any observed changes in the cell as the reaction proceeds.

2

17

Question 26 (5 marks) A student wants to determine the concentration of ethanoic acid in household vinegar. To do this, she makes a primary standard using anhydrous sodium carbonate (Na2C03). (a)

IdentifY TWO properties needed for a compound to be a suitable primary standard.

1

(b)

The student weighs a 7.52 g sample of anhydrous sodium carbonate and dissolves this completely in a 250 mL volumetric flask.

1

Calculate the concentration of the resulting sodium carbonate solution.

(c)

The student titrated 25.0 mL aliquots of the primary standard against the household vinegar. She found that it took an average of 24.3 mL of vinegar to neutralise the sodium carbonate. Determine the concentration of ethanoic acid in the original vinegar sample.

18

3

Question 27 (4 marks)

The historical development of theories of acids and bases provides an insight into how chemists are able to build on previous knowledge to improve scientific understanding. With reference to Lavoisier, Davy, Arrhenius and Bronsted and Lowry, outline each major acidbase theory using specific examples where appropriate.

19

4

Question 28 (4 marks)

In some developing countries, arsenic(III) ions (As3+) in groundwater present a serious health risk for many people. When concentrations exceed 10 ppb, arsenic poisoning can result from drinking contaminated water. The Solar Oxidation and Removal of Arsenic (SORAS) process irradiates drinking water in plastic bottles with sunlight to reduce arsenic(III) levels. Atomic absorption spectroscopy (AAS) can be used to determine the concentration of arsenic(III) ions in the water. The absorbance values for some standard solutions of arsenic(III) ions are shown in the table below. Concentration ofAs(III) ions (ppb)

Absorbance

50

0.12

100

0.23

150

0.35

Samples of groundwater from Bangladesh were tested using AAS and the absorbance values before and after SORAS treatment were measured and recorded. Sample

Absorbance

Groundwater sample before treatment

0.28

Groundwater sample after treatment

0.13

Question 28 continues on page 21

20

Question 28 continued Evaluate the effectiveness of the SORAS treatment in preventing arsenic poisoning from drinking groundwater.

21

4

Question 28 continued Evaluate the effectiveness of the SORAS treatment in preventing arsenic poisoning from drinking groundwater.

4

I I I

21

Question 29 (4 marks)

A section of a cellulose molecule is shown below. H

4 H

OH

OH

0

0

0

H

/

OH

Assess the suitability of cellulose as an alternative to petrochemicals and its potential as a raw material for chemicals used in industry. Include relevant chemical equations in your answer.

Question 30 begins on page 24

22

BLANK PAGE

23

Question 30 (4 marks) A student made a natural acid-base indicator by placing the flowers of a plant he found in his garden into boiling water for several minutes. The solution became strongly coloured and he used it to develop a pH indicator chart. His flower indicator results are compared with those for phenolphthalein and methyl orange in the chart below.

He then used the flower indicator along with phenolphthalein and methy 1 orange to test two unknown, colourless solutions, X, Y and z. The results of his experiment and his conclusions are below.

Results Phenolphthalein

Methyl Orange

Flower Indicator

X

colourless

yellow

green

y

colourless

yellow

purple

z

pink

yellow

red

Conclusions Unknown Solution

Inference

X

strongly acidic

y

weakly acidic

z

strongly basic

24

4

Question 30 continued Using the data from the experiment, assess the accuracy of the student's conclusions and the validity of using the natural indicator to distinguish between acidic and basic solutions.

25

Question 31 (6 marks) HA and HB are two monoprotic acids with the properties shown below.

(a)

Acid

Concentration (mol D 1)

pH

HA

0.10

1.0

HB

0.85

1.0

Using these acids as examples, explain qualitatively how two acids of different concentrations can have the same pH.

26

3

Question 31 continued (b)

In a titration experiment, 0.100 mol L- 1 solutions of both acids, HA and HB, were titrated with a 0.100 mol L- 1 sodium hydroxide solution. The conical flask contained 25.00 mL aliquots of the acids as well as a pH probe to measure pH during the titration. For each acid, sketch a curve on the corresponding grid below showing how the pH changes with respect to volume of base added. For each acid, indicate on the graph the volume of base required and the approximate pH at the equivalence point.

AcidHA 14 13

I

12 11

10 9 8

:r:

c.

7 6

5 4

3 2 1

"o

5

10

15

25

20

30

35

40

45

50

35

40

45

50

Volume of NaOH added (ml)

AcidHB 14 13

12 11

10 9

8

:r:

c.

7

6

I

5 4 3 2

1

"o

10

15

25

20

30

Volume of NaOH added (mL)

27

3

Question 32 (6 marks) Early in the twentieth century, the German chemist Fritz Haber discovered a process for synthesising ammonia from atmospheric nitrogen that is still in use today. In 1909, Haber was able to demonstrate a process that produced ammonia at a rate of about 125 mL per hour. The process was then purchased by the German chemical company BASF, which assigned Carl Bosch the task of scaling up Haber's laboratory process to industrial-level production. Discuss the impact on society of the development ofthe Haber-Bosch process for synthesising ammonia.

Question 33 begins on page 30 28

6

BLANK PAGE

29

Question 33 ( 5 marks) The data in the table below show the results of some tests on an untreated water source for a municipal water supply over a seven-day period.

..-<

Characteristic

Units

Turbidity

NTU pH units

N

~

~

"'~

1/)

""""~

~

\0

~

t-

~

Q

Q

Q

Q

Q

Q

Q

2.60

2.21

2.20

2.91

3.56

3.69

3.95

4.01

7.2

7.0

6.9

7.0

7.0

7.1

7.1

6.9

lOOmL

3

2

4

8

19

25

38

46

Iron

ppm

0.31

0.28

0.27

0.28

0.31

0.32

0.31

0.30

Aluminium

ppm

0.24

0.22

0.22

0.21

0.22

0.23

0.23

0.22

Nitrates

ppm

1.20

1.21

1.19

1.20

1.20

1.21

1.22

1.22

Phosphates

ppm

0.02

0.02

O.Ql

0.02

0.02

0.02

O.Ql

0.02

pH Escherichia coli (E. coli)

organisms/

Assess the quality of the water over the seven-day period, outlining if and how the water quality may have been compromised and describe any processes used in a water treatment plant that would make it suitable for drinking.

30

5

Question 33 continued

31

BLANK PAGE

32

lilT

~

CATHOLIC SECONDARY SCHOOLS ASSOCIATION OF NSW 2014 TRIAL HIGH SCHOOL CERTIFICATE EXAMINATION

CSSA

Chemistry Section II 25 marks Attempt ONE question from Questions 35-39 Allow about 45 minutes for this section Answer parts (a)-( c) of the question in the Section II Answer Booklet I. Answer part (d) of Question 34 in the Section II Answer Booklet Answer patis (d)-(e) of Questions 35 or 36 or 37 or 38 in the Section II Answer Booklet 2. Extra writing booklets are available.

Show all relevant working in questions involving calculations. Pages Question 34

Industrial Chemistry .......................................................................

34-35

Question 35

Shipwrecks, Conosion and Conservation ......................................

36

Question 36

The Biochemistry of Movement ....................................................

37

Question 37

The Chemistry of Art .....................................................................

38

Question 38

Forensic Chemistry ........................................................................

39-40

33

3800-1

Question 34- Industrial Chemistry (25 marks) Answer parts (a)-(c) in Section II Answer Booklet 1. (a)

(i)

Sulfuric acid is one of the most important industrial chemicals. Herman Frasch developed a process for obtaining sulfur from mineral deposits that bears his name today.

2

Describe the properties of sulfur that allow it to be obtained by the Frasch process. (ii)

When conducting the Frasch process, a number of environmental issues must be considered.

2

IdentifY the environmental considerations and evaluate their significance. (iii)

One step in the process of sulfuric acid production involves the following reaction

5

Outline the conditions used for the above reaction in the production of S03 and assess these in relation to equilibrium and rate considerations.

(b)

(c)

(i)

During the course, you performed a first-hand investigation to observe a saponification reaction and prepare a sample of soap. Describe the procedure you used, including any safety precautions considered.

5

(ii)

JustifY the classification of soap as an anionic surfactant.

1

Three methods of producing sodium hydroxide on an industrial scale are the mercury, diaphragm and membrane processes. Discuss the chemistry involved in each process and any technical and environmental issues that must be considered.

Question 34 continues on page 35

34

6

Answer part (d) of the question in Section II Answer Booklet 2. (d)

In the 1860s, Ernest Solvay developed the chemical process that bears his name to massproduce sodium carbonate. This process is represented in the flow chart below.

Brine

Soda Ash

\:>

co,

Limestone

Calcium Chloride Adapted from Wikipedia Commons, © Eric A. Schiff, 2006 http://commons.wikimedia.org/wiki/File:Solvay_Process.png

Using appropriate chemical equations, describe the chemistry involved in Steps I and 2 in the above flowchart.

End of Question 34

35

4

Question 35- Shipwrecks, Corrosion and Conservation (25 marks) Answer parts (a)-( c) in Section II Answer Booklet 1.

(a)

(b)

(c)

(i)

Using chemical equations, explain why an iron nail will corrode when partially immersed in water.

3

(ii)

Identify aod for a factor that would increase the rate of corrosion of an iron nail.

2

(i)

Outline a method you used to show how ONE named factor affected an electrolysis reaction.

2

(ii)

Justify the method you used in (b) (i).

3

Outline the contributions of Galvaoi, Volta, Davy and Faraday to our understanding of electron traosfer reactions.

4

Answer parts (d)-(e) of the question in Section II Answer Booklet 2. (d)

(i)

The iron that is produced in a blast furnace contains about 4% carbon while steel generally contains about 1.5% carbon.

2

Compare the suitability of iron and steel for shipbuilding. (ii)

(e)

Describe a strategy for protecting the iron or steel hull of ships from corrosion.

Prior to the discovery of the wreck of RMS Titanic, it was widely believed that conditions on the sea floor 3800 m below the surface would preserve the ship virtually intact. When it was discovered in 1985, pictures showed the appearaoce of needle-like rusticles and extensive corrosion throughout what remained of the ship. Evaluate how the discovery of RMS Titanic has changed the direction or nature of scientific thinking, with respect to slow corrosion at great depth.

End of Question 35

36

2

7

Question 36- The Biochemistry of Movement (25 marks)

Answer parts (a)-(c) in Section II Answer Booklet I. (a)

(i)

What is the name given to the stage of cellular respiration that is anaerobic?

1

The process identified in part (i) begins with glucose and produces 74 kJ of energy per mole of glucose metabolised. (ii)

Write a balanced chemical equation to represent this process.

2

(iii)

Calculate the theoretical energy produced from 250 g of glucose.

2

(b)

Describe a first-hand investigation that shows the effect of temperature on activity for a named enzyme and describe ways to improve the procedure to make it more valid and reliable.

(c)

Glycerol is a colourless, highly viscous liquid, soluble in water and with a sweet taste.

5

(i)

Draw the structure of glycerol and identifY its systematic name.

1

(ii)

Explain why glycerol has a higher viscosity than ethanol.

2

Answer parts (d)-(e) of the question in Section II Answer Booklet 2. (d)

(e)

Carbohydrate loading is a strategy used by endurance athletes to increase the amount of carbohydrate stored in their muscles. It generally involves eating large amounts of carbohydrate and reducing exercise several days before an event. (i)

Outline how carbohydrates are stored in the body.

2

(ii)

Discuss the effects of carbohydrate loading before an event on the performance of endurance athletes.

3

Assess the impact of advances in biochemistry on the performance of sprinters and short distance runners.

7

End of Question 36

37

Question 37- The Chemistry of Art (25 marks)

Answer parts (a)-( c) in Section II Answer Booklet 1. (a)

for the position of chromium in the periodic table in of its electron arrangement, ionisation energy and electronegativity.

(b)

You performed a first-hand investigation to observe the colour changes of a transition metal ion as it undergoes oxidation.

(c)

5

(i)

Identify the transition metal you used in this investigation.

1

(ii)

for the colour changes you observed and recorded.

3

Bright colours such as green, blue, red and yellow were used extensively by ancient Egyptians in art, body painting and makeup. (i)

Select ONE of the colours above and identify the name or chemical formula of a mineral used to produce the selected colour.

1

(ii)

Outline the procedure that the Egyptians would have followed to make paint from minerals such as the one you identified in (c) (i).

2

(iii)

Outline a health risk to the ancient Egyptians involved in using minerals in face paint or makeup.

1

Answer parts (d)-(e) ofthe question in Section II Answer Booklet 2. (d)

(e)

(i)

Compare emission and absorption spectra.

2

(ii)

Explain how the spectra of elements both ed and contradicted the atomic model proposed by Niels Bohl: in 1922.

3

Evaluate the impact of spectroscopic techniques on analysing the range of different pigments used by artists throughout the ages.

End of Question 37

38

7

Question 38- Forensic Chemistry (25 marks) Answer parts (a)-( c) in Section II Answer Booklet I. (a)

(i)

Explain how comparing the amino acid sequences of proteins can be used to identifY individuals.

2

(ii)

The diagram below shows DNA evidence used in a case to determine the identity of the father of a child.

2

- -- -

mother

child

0130

-- - --

Use this evidence to make an assessment of whether the man is the father of the child.

(b)

(i)

The chemical structures of two disaccharides are shown below. CH20H

~ c~tH OHH OH

0 H

OH

~

~

1

H

CH20H

OH H

0

OH

Disaccharide A

H

0 OH

Disaccharide B

IdentifY which of these disaccharides is a reducing sugar and for your choice. (ii)

Outline and justifY a chemical test you performed in the school laboratory to distinguish between these two sugars.

Question 38 continues on page 40

39

3

(c)

Toluene is an organic compound with molecular formula C7Hs. A mass spectrum for toluene obtained using mass spectrometry is shown below.

100 ~

>R 0 ~

80

6

Q)

u c ro

"0

c

:::J .0 <( Q)

60-

Toluene

c,H8

4Q-

:5til Q) ~

2Q-

0.0 15

,!.I. I

0

30

45

' 60 m/z

,, I 75

90

105

Adapted from Wikimedia Commons http://commons. wikimedia.org/wiki/File:Toluene_ ei_ms.PNG

(i)

Explain how mass spectra like this are produced.

3

(ii)

How could this mass spectrum be used to identifY toluene in a mixture of unknown compounds? ·

2

Answer parts (d)-( e) of the question in Section II Answer Booklet 2. (d)

(e)

(i)

Using an example, for the use of line emission spectra in forensic analysis.

2

(ii)

Explain why each element produces a unique emission spectrum with lines at different wavelengths.

3

Using a specific example, analyse the development and impact of a sensitive analytical technique on the outcome of forensic investigations.

End of Pape1·

40

7

BLANK PAGE

41

BLANK PAGE

42

BLANK PAGE

43

EXAMINERS Jonathan Saurine (Convenor) Moira De Domeneghi Lee McFarlane Andrew Shelley

Kincoppal-Rose Bay School, Rose Bay Kincoppal-Rose Bay School, Rose Bay St Joseph's Institution International, Singapore Canberra Grammar School, Canberra

CSSA Copyright Notice (2011) CSSA Trial HSC Examination papers in both hard and electronic format are subject to copyright law. Individual papers may contain third Party Copyright materials. No CSSA papers are to be reproduced (photocopied, scanned) or communicated by schools except in accordance with the

Copyright Act 1968. CSSA papers arc provided for examination purposes only and should not be made available to students for any other purpose than examination and assessment. CSSA Trial HSC Examination Papers must not be placed on the school intranet, the internet or on any mobile device.

44

-(1)

''

CSSA CATHOLIC SECONDARY SCHOOLS ASSOCIATION OF NSW 2014 TRIAL HIGHER SCHOOL CERTIFICATE EXAMINATION CHEMISTRY- MARKING GUIDELINES

Section I

Part A 20 marks Questions 1-20 (1 mark each) Question

Answer

Outcomes Assessed

Targeted Performance Band

I 2 3 4 5 6 7 8 9 10 11 12 13 14 IS 16 17 18 19 20

D B D B

H9,H8 H9,H8,HI3 H6,Hl3,HI4 H8 H4,HI4 H8, Hl4 H9,HIO ,HI4 H8,Hl3 Hl4,HII,H8 H4,H7,H8 H6,H8 H7, H8, Hll H8 Hl2 H9, HIO, Hl4 H4,H6, Hl3 H2,HIO,H!3 H4, HS,H14 HIO, H9,H13 H7, H8, H13 H4, H10, Hl4

2-3 2-3 3-4 3-4 2.-:J. 3-4 4-5 5-6 4-5 3-4 3-4 3-4 4-5 4-5 3-4 4-5 4-5 5-6 5-6 5-6

c c c

A A D

B

c

A A A

D A

c c

D

i

1 DISCLAIMER 1M irlformaoon DJrlltned in~
1'-

3800-2

I

;

Section I

Question 23 (4 marks)

Part B -55 marks

Outcomes Assessed: H9, H13, H14 .LU~oc;u..o.

Question 21 (3 marks)

Outcomes Assessed: H2, H7 ,o. - ·

• • •

....

,,.

···-H~- ~-••

.. -

Criteria

Mark

Identifies and distinguishes between the type of covalent bonding present Describes the resonance structure in ozone Relates the strength of the covalent bonds to the bond energy Identifies and distinguishes between the type of covalent bonding present Relates the strength of the covalent bond to the bond energy Identifies and distinguishes between the type of covalent bonding present

•

• •

~·--"'

•

OR

•

• •

3

•

2

•

I

•

•

Relates the strength of the covalent bond to the bond energy

Sample answer: Oxygen (02) has a double covalent bond between the two oxygen atoms. Ozone (OJ) has a double covalent bond between one pair of oxygen atoms and a coordinate covalent bond between the other pair of oxygen atoms. These bonds resonate chemically back and forth such that the overall bonding in the molecule can essentially be viewed as a 1.5 covalent bond. The double covalent bond in oxygen is a stronger bond than the 1.5 covalent bond in the ozone. More energy is needed to break the covalent bond in oxygen than either of the covalent bonds in ozone and this explains why oxygen has a higher bond energy than ozone.

• • • • • •

c;f

VIUOf.&n .. o:;; .UUIUUO J•'f'

Criteria Describes a sequenced process for the production of the polymer from a natural raw material Identifies the physical processes involved in the production of the polymer Identifies and describes the chemical processes involved in the production of the polymer Includes all relevant chemical ~uations Describes a sequenced process for the production of the polymer without starting from a natural raw material Identifies the physical processes involved in the production of the polymer IdentifieS: and describes the chemical processes involved in the production of the polymer Includes all relevant chemical equations Describes a sequenced process for the production of the polymer Identifies and describes the chemical processes involved in the production of the polymer Includes some relevant chemical equations Identifies a physical processes involved in the production of the polymer

Mark

4

3

2

OR Identifies and describes a chemical processes involved in the production of the polymer

I

OR

•

Question 22 (3 marks)

Outcomes Assessed: H3, H4, H7 .& . . .

" . " . . .& . . .

•

•

Relate its use to at least one property

• • •

Sample answer:

, , . . . . . . . . . . ~ .......... _. . . . . - . .

Criteria Identifies the radioisotope and field Relate its use to at least two properties Identifies the radioisotope and field Relate its use to at least one property Identifies the radioisotope and field

•

Includes a relevant chemical equation

Mark 3

2

OR

I

Polyethylene Ethylene (CH2=CHz) is usually obtained from several natural sources. Crude oil (petroleum) is firstly fractionally distilled (physical process) to produce naptha that can be thermally cracked (chemical process) to produce ethylene. CtsHJ2--+ 2C2fit + C3H6 + CsHu The ethylene produced is separated by fractional distillation (physical process) and the ethylene monomer undergoes addition polymerization (chemical process) to form polyethylene.

(C,H,),-> (·CH,-CH,-), At moderately high temperatures and high pressure, with the use of an initiator such as benzoyl peroxide LDPE is formed.

Sample answer: Iodine-131 is used in medicine where it is ingested by a patient to treat thyroid disorder or cancers. It has a half life of only eight days which is long enough for transportation to where it needs to be used and short enough to minimise a patient's exposure to radiation. Iodine-131 emits beta and gamma radiation. The beta radiation allows any abnonnal tissue or cancer cells to be destroyed and the gamma radiation allows for the external imagining so that the target cells or area can be imaged.

2

3

The lr.bml!loo ooillned In !lis 00tum1u1t Is klletlded lor the ~ asslstooee d leact.ll\ll statt. a tiDe!; not cons~llle
OISCLJ.lMER The lnlormalioll coolaifled In 1llis documenlls Wooded lof N prolas.sl«oal asslslot1C11 of leactillg $lilf.ll does 1101 constMe ildW:& liJ ~~. fur'illef a Is IIOIIhe !t\lam'on o1 CSSA 1o p!Wide spedicma.11irt;j O!h:;omas lofall posdle Tria HSC answers. Ratt.er lhe purpose Is 1o ptOWJe leacllefs ~ lnloor.aioo so lhall!leycan ~up~oru. undersland apply HSC ~lequ\'emenls, a.s~by~ NSW !looldofSiucfies. No gr.raranteearw
OISCI..AIMSR

~yorresponsibW!ylorlllaaco.trllq,~SOlUSeM!l!ssoiOMyMarkflg~pro'lideclforlheTiiaiHSoJ~Ers.

am

,' : Question 25 (4 marks) (a) I mark

Question 24 (3 marks)

Outcomes Assessed: HJO, H12, H13 ..1

oc•

I<'~~U.

..1 o:;1

•

Criteria Calculates the number of moles of ethanol burned Calculates the energy absorbed by the water Calculates the heat of combustion in kJ mor' Calculates the number of moles of ethanol burned Calculates the energy absorbed by the water Calculates the number of moles of ethanol burned

•

Calculates the energy absorbed by the water

•

Calculates t"@__heat of combu_§_tion in kJ mol~

• •

•

•

•

Outcomes Assessed: H7, Hl2 Tar2eted Performance Bands: 2-3

lH , , . .. , .... ,., .LIIUUU.. o .J-'T

Mark 3

,

Mark

Criteria Correctlv labels anode. cathode and the direction of election flow

•

Sample answer:

2

OR

e

I

OR

-~

salt bridge

Cu metal strip

Zn metal

strip -··---

--

---

---

Sample answer:

Anode

<,.;.,

Cathode

Mass of ethanol~ 137.15-135.14 ~ 2,0lg

.6.H = -mcllT ~ -250 X 4.18 X (47.5-17.5) ~-30 9841

,,;::- ..., .

,

.~:,-:·.

CufN.0312

Zn{N0 312

solutton

solution

Molar mass ofC,H50H ~ 46,068 Moles ofC,H5 0H ~ 2.01146.068 ~ 0.04363 mol Therefore molar AJI

.....

~

30 984/0,04363 ~ 710 !54 J mor'

Criteria Writes a correctly balanced net ionic eouation for the overall cell reaction

•

~7!0kJmor 1

Mark

Sample answer: Zn (s) + Cu+2(aq)-> Zn2++ Cu (s) (c) 2 marks

Outcomes Assessed: H7, Hl4 .... 04 . . . . . . . . . -"

.................................

_,--,-

• •

Criteria Identifies AND gives correct reason for colour ch311g~ Identifies the correct colour chaiJge

•

Gives a valid explanation for an unidentified colour change

OR

Mark 2 I

Sample a11swer: As the reaction proceeds, the Cu2+ ions in solution are re'duced to form Cu (s) on the cathode. As the concentration of blue Cu2+ ions decreases in the catholyte, it fades to a less intense shade of blue.

4

5

The lnb-mallon CGillaioed in tits !Soc1.menl is lnlended for lila professiona ass!slooce of leaching sW!'. Ndoes 1101 coosl:Me art.ice to ~ Fu~ n is notlhfl il!!mtion of CS5A lo prtriide specii'JC ~ ~ b" at p®sl!!e Trial HSC a'ISW\lfS. Railer !he I!'JIJ)OSII Is 1o pro.,;oo leacl\ef$ wilt\ irlki!rnifun so lhat ltleyean belief expke, li!'K!efsland ai'ICI awt)'HSC mM:irlgl'l!qiJin)merlts, aseslablished lty!lleNSWBoarlld~. h'o~anlee «warranty Is mad!! or~ wilh !$peel lo the epp1!ca\iotl or 11111 of CSSA Marking Gl.l!deines in relalion 1o MY spear~: lrlal exam question 01' anroorer. Till! CSSA asrunes 110

DlSClAIMER The fllformalion contafnro in !lis document Is ~ for 1M ptoressional assls!anca of luelling slafl. n does not consliluttl advice to sludenls. FUrltlet ~ Is nallhe !Mol!on or CSSA !o pw.ide: spe«.c marking O'J!con'!es b iii possible Tt!al HSC anwrers. ~ the putpose Js to ptO'Ide leadleB w\\h ll'llomi3'Jon oo !lui lllay can b!!lter explore, undersland and 2ll¢f HSC marklrt;J req!Nemmls,ll$ es\aNs11ed by tile NSWI!oord of Sludles. No~ 01' wooantj !s made 01'11T¢ed with respect to ~ ~ 01' U.~a of CSSA Marking Gulclrinl!s in reli!llon to any~~ lrial exam ~1:00 01' anroorer. The CSSA assumes no liatlityllf ri!SpOI\Sibi!lty br!he aw.Jracy, ~or l!Seflh'!ess of any Ma!k!ng ~es jlfiiYided blhe Trial HSC papeB.

OSCIAIMER

iabi«yOI'res~&~rV!ellCtlllaty,~OI'useMlessol'any~G~proo.idedb'tileTtla!HSap!!fS.

i

i

(c) 3 marks Outcomes Assessed: HI 0, Hl2, HI3 Targeted Performance Bands: 3-4

Question 26 (5 marks) (a) 1 mark Outcomes Assessed: Hll

Criteria •

Lists TWO correct characteristics of a

standard

Sample answer: Any TWO of the following:

Mark

• • •

Correctly calculates the concentration of ethanoic acid in vinegar solution

Writes a correctly balanced equation Correctly calculates the concentration of ethanoic acid in vin~gar solution

•

Does not lose or absorb water from the environment (efflorescent/deliquescent)

OR

• •

High purity Dissolves easily and completely in water

• •

Writes a correctly balanced equation Correctly calculates the number or'moles of sodium carbonate

•

Known composition

• • •

Writes a correctly balanced equation Correctly· calculates the number of moles of ethanoic acid Writes a correctly balanced equation

•

Correctly calculates the number of moles of sodium carbonate

•

Correctly calculates the number of moles of ethanoic acid

3

2

OR

OR

Criteria

Mark

I

OR

Sample answer: ri(Na,CO,) ~ m/Mr ~ 7.52/(22.99 X 2 + 12.01 + 16.00 x 3) ~ 7.52/105.99 ~ 0.070950089 ... c(Na2CO,)

n/v

Sample answer: 2CH,COOH + Na,CO,-. 2CH,COONa + H20 + C02 n(Na2CO,)

~

0.070950089 ... /0.25 ~ 0.283800 ... ~ 0.284 mol 1·1 (3 sig fig)

~

cv

~0.284x0.025 ~

n(CH,COOH)

c(CH,COOH)

~

0.0071 moles

~

2n(Na2C03) 0.0142 moles

~

n/v

~

0.0142/0.0243 0.584362 ... ~ 0.584 mol 1·1 (3 sig fig) ~

6 DISCLAIMER The inklmlation cool
I

7 DISCLAIMER The irllorrro!ion oonlairled In !his documenl is inle!lded br fie profess!«

marl:.ing •emenls, as establls/ied byllle NSW &:lard of Slur.lles. No gua~anleeorW3oTill!yl$ made or~ willl respoct to lhe ~IM!o or use of CSSII t.lm:lo;j Gu!OOlines In ceallon 10 any speOfic 1rial exam ques&:~n or answer. The CSSA aswmes no ~lily or responsltlily ~ttl!! ac::t\l!iq, ~ 0( useh!lrwS$ of any Making Guidelines prl!l!ded fot lhe Trial HSC pap~n

Question 28 (4 marks) Outcomes Assessed: H4, HS, HB, HJO, H13, H14

Question 27 (4 marks) Outcomes Assessed: H2, H13, HJ6 .1. HI

•

•

O:::JC::W' A rt;;;IJUI IIIWUl.'C:

.UWTJW~o

.LiiT}!t;n:::u ceT/VIIUUTJLC .UUr

,.,-_,

Criteria Outlines FOUR theories correctly using examples for at least THREE of the theories Outlines FOUR theories correctly but without any examples

OR

• • •

Mark 4

Outlines TWO theories correctly Outlines ONE theory correctly

3

2 I

• •

Sample answer: Lavoisier's oxygen theory: After observing the reactions ofnon~metal oxides in water, he proposed that acids are substances that contain oxygen. The theory could not explain the basic properties of metal oxides. Davy's hydrogeti theory: After observing HCI and HCN, he proposed that acids were substances that contained hydrogen. The theory could not explain compounds containing hydrogen that were not acidic or basic (i.e. CRt). Arrhenius' hydrogen ion theory -After working on electrolytes, he proposed that acids were substances that released hydrogen ions (It) in solution, e.g. HCI ~ fr +cr. He also proposed that bases were substances that produced hydroxide (OHJ ions in solution. The theory could not explain why ·carbonates and metal oxides behave as bases despite not containing hydroxide ions. Bronsted-Lowry's proton donor/acceptor theory: They proposed that acid/base reactions are proton exchange reactions. Acids: proton donors HN03 + HzO ~ H 30+ t)~IOJ­ Bases: proton acceptors NH3 + HzO ~ NH/ + OH"

Mark

Criteria

• • •

Outlines THREE theories correctly with examples

-.-~

•

• •

Deduces the concentrations of ASJ+ ions before and after treatment Discusses the effectiveness of reducing the concentration of As 3+ ions Evaluates the effectiveness of the SORAS treatment in of preventing arsenic poisoning Deduces the concentrations of As 3+ ions before and after treatment Evaluates the effectiveness of the SORAS treatment in of reducing the concentration of AsJ+ ions Discusses the effectiveness of reducing the concentration of As3+ ions by referring to absorbance values Evaluates the effectiveness of the SORAS treatment in of reducing the concentration of As 3+ ions or nreventintr arsenic noisonintr Deduces the concentrations of AsJ+ ions before and after treatment

OR

•

Outlines the effectiveness of reducing the concentration of As 3+ ions by referring to absorbance values --

4

3

2

I

Sample answer: From the calibration data, an absorbance value of 1.0 corresponds to a concentration of 429 ppb (150/0.35). Before the treatment, the concentration of arsenic ions was 0.28 x 429 = 120 ppb. After the SORAS treatment the concentration of arsenic ions was 0.13 x 429 =56 ppb. The SORAS treatment has been effective in reducing the concentration of arS.i!.iliC ions to just less than half of their original concentration, however, the concentration after SORAS treatment is still greater than the minimum acceptable concentration of 10 ppb. Therefore, while the treatment has been effective at reducing the concentration of arsenic ions and reducing the risk of poisoning, it has not.been effective to prevent arsenic poisoning. To prevent arsenic poisoning, the concentration after SORAS treatment would have to be less than 10 ppb.

8

9

OISCLAIMER The lMlnna\ion coni~ In lh!s doo.lmenlls!~ for toe pr!lesslooal ass!sl :ldioos prttMed for U:.e Trm! HSC IJG!leiS.

OISCL.AIMER The Jnfoonallon IXN"IIained In this ®cumeol is in!mded kJr 100 professlorlal assislance of ~ slalf. II does not ronstaute advi<:e lo sludenls. FllllhEf HIs no\ lhe Jnloolloo of CSSA lo pltl'llde specific mming 1!t11Come$ for aa possil*! TMI HSC at1~ Ralhef &le purpose Is to proMe l~ w\lh information so 1h3t lhey c:<~t~ belief explole, ~land and 3fl¢Y HSC malking ~. as oolablished by lila NSW Soard of Sluofes. No QWanlwOI'Wilrl'anlyls made« imp«edwi111 respect lo 1he ~ 01' use ol CSSA M31!00g Gu!de«nes In rel(llioo kl anyspedfte lrlal exam qwsl!oo 01 OOS'Irer. The CSSA assumes oo NMy 01 resp:l(!Sibittj kJr It'll! ac:wrney, compleletless OfmefulnelSol any Mao1dl1g ~ p(O'I.dlld for 1l1e Trl:ll HSC pi!pe!S.

Question 29 (4 marks)

Question 30 (4 marks)

Outcomes Assessed: Hl, H4, HS, H9, H13

Outcomes Assessed: H2, H12, H14

"" .. ,

......... """

~•

.......

.,, ..... , .... ~ ....... n .... o ..,.-,..

Criteria

•

• • • • •

•

Demonstrates a thorough knowledge of the chemical processes used to produce

chemicals for industry from cellulose, including chemical equations Outlines the benefits and limitations of using cellulose as a source of chemicals for industry Makes a judgement about the suitability of cellulose as a source of chemicals for industry Demonstrates a thorough knowledge of the chemical processes used to produce chemicals for industry from cellulose

Outlines the benefits and limitations of using cellulose as a source of chemicals for

4

• • 3

• •

Identifies one reason for needing an alternative source of chemicals and/or energy

•

Identifies one benefit or limitation of using cellulose

Criteria Correctly assesses all THREE conclusions and makes a judgment of the validity of the natural indicator as an acid-base indicator Correctly assesses TWO conclusions and makes a correct judgment of the validity of the natural indicator as an acid-base indicator Correctly assesses THREE conclusions Correctly assesses ONE conclusion and makes a correct judgment of the validity of the natural indicator as an acid-base indicator

•

•

Mark 4

3

2

Correctly assesses TWO conclusions Correctly' assesses ONE conclusion

OR Makes a correct judgment of the validity of the natural indicator as an acid-base indicator

I

Sample answer:

OR I

OR Sample answer: Cellulose is a biopolymer formed by the condensation polymerisation of glucose monomers and represents one major source of carbon compounds that can be used as an alternative to fossil fuels for the production of ethylene. Cellulose contains the basic long carbon chain structure needed to build compounds that are presently made from petrochemicals. Cellulose can be hydrolysed to produce glucose. Fermentation of glucose will produce ethanol that can be distilled to produce a more concentrated form. The ethanol can then be dehydrated to produce ethene in the presence concentrated sulfuric acid. The ethanol can be used as a solvent as it is widely used for this pwpose in industry. Ethanol can also be added to petrol. The ethene can be used to derive the monomers used to make many plastics through addition polymerization. Ethene can also undergo and halogenation to form PVC, refrigerants and other solvents. Cellulose is a renewable source, unlike the raw materials from petrochemicals. This will reduce our dependency on the depleting/non-renewable supplies of fossil fuels. Fuels made from cellulose are however currently more costly to produce than fossil fuels and to grow sufficient plants would result in extensive land clearing. Cellulose currently has limited potential as a suitable alternative to petrochemicals for producing chemicals for industry. Further research to reduce the cost and improve yields is needed before it can become a viable source of chemicals for industry.

10

"""""''

........................................... ...,-..,

OR

• 2

Outlines the benefits and limitations of using cellulose as a source of chemicals for industry Identifies a compound derived from cellulose

•

·-~

OR

industry Demonstrates a thorough knowledge of the chemical processes used to produce chemicals for industry from cellulose, including chemical equations

OR

•

Mark

llwi'lforma!Kio ~ tn tis do:;umeot Is ~ lor till profmioroal iWllstai'ICIJ d leadiing slaff. II does 1101 COMb arMa! lo sludmls. FtHlller KIs nol b'le lnkntiDn d CSSA Ill p«Mde spedor:: ~ OOlCOmes lor ill possiJIB Trial HSC wwers. RatltY tile Jllllpose Is ID prwide leachers wilh il\fornwticn so lllallhey can bell« exploru. Lllldealand atld ~y HSC ma~l<.i"tg requiremenls, as eslatAslled lly lle NSW SoalrJ d SWes. t.il guaranlee Ol"warranly Is made or 11'11r.&:d wilt! tespe!:IIO lite~()( liSa r:J CSSA Ma!lm;j GUddroes In rela!iOI"IIo i'IIY~ !rial exam que~()( answer. The CSSA as&JII\i!S no .ii!lil.lyOI" responslbiily br U\e tor::eur;q, ~ or ~el!kless r:J 1'4r1 Markllg Gllklelines provkled lor U\e Tli
X- The conclusion is partially accurate. It is an acid, but it is not strongly acidic as it must be between pH 4.5 and pH 6.5. Y- The conclusion is not necessarily accurate. The solution could be between pH 6.5 and pH 8.5, so it could be slightly acidic, neutral or slightly basic. Z- The conclusion is accurate. The solution must have a pH greater than 13. The natural indicator has limited validity in assessing if a solution is acidic or b3SlC due to it being purple in the weakly acidic, neutral and weakly basic range. This limits its use in distinguishing between acidic and basic solutions when used alone.

11

DISCLAIMER The lnlormat"on coola'ned In U"ll5 !1ocucr.em Is ~ b" !he pr«essional asslsli!IQ of leidllog staff. Hdoes not Cllii$QUW advice k1 Muclents. fllftle( Mis no1 the !oleo~ of CSSA to pnM:Ia ~ ~ ou1t:omes fill" a'l possj1le Trial HSC answers. Riilhef lhe pur,oose Is !o ptO'ilde leachels wilh infomlalion so 111a1 Liley can bell£( expklte, undelsl¥4 and ififlly HSC marltir.;j req.tirements. as eiabll!OO;I by !he NSW l!ootd orSiu!W.. No guarantee orwwranly ls mada or iiT¢ed wilh re~ lo 11\e ~ 01" use or CSSA Matk~ ~sIn rEt1!!on to tiN/ speclk ~exam question()( wwer. The CSSAassumes no Kal:i!i!y or resp:M'~Sltffiy lor llle accurocy, ~ ()( uselulllessd MY Ma!l:log GulrJeliroes provided for Ill& Tria! HSC papus.

I

(b) 3 marlcr Outcomes Assessed: H2, Hl3

Question 31 (6 marks) (a} 3 markr Outcomes Assessed: H2, HIO, H13 _,__. -~---- -· -····-··-- .......... -y •.• -

.z llTJ;:c:n:;u

•

Criteria Correctly defines strong and weak acids in of ionisation Identifies that solutions of equal pH must have equal concentrations oflt/H30+ ions and explains how this is possible in of partial/full ionisation Uses balanced equations to demonstrate concept Correctly defmes strong and weak acids in of ionisation

•

Identifies that solutions of equal pH must have equal concentrations oflt"IH30+ ions

• • •

Mark 3

•

2 Identifies that solutions of equal pH must have equal concentrations oflt"/H30+ ions

and explains how this is possible in 6f partiallfull ionisation AND • Uses balanced equations to demonstrate concept • Correctly defines strong and weak acids in tenns of ionisation

OR

•

Identifies that solutions of equal pH must have equal concentrations of W /H 30+ ions and explains how this is possible in of partial/full ionisation

J-u

•

•

Shows that HB has a higher pH at the equivalence point than HA

•

Starts both curves with an acidic oH

Mark 3

2

OR

and explains how this is possible in of partial/full ionisation

OR

.uuuu~.

Criteria Shows that both acids require the same volume of base Shows that HB has a higher pH at the equivalence point than HA Starts both curves with an acidic pH and the correct volume of base at the equivalence ooint Shows that both acids require the same volume of base Shows that HB has a hig:her nH at the eauivalence noint than HA Shows that both acids require the same volume of base

• • • • •

AND

.c t!T/VI lliUUl'C:

I

Sample answer: HA is a strong acid and therefore ionises completely, according to the following equation HA + HzO ~ H30+ +A. HB is a weak acid and therefore ionises partially, according to the following equation HB + HzO ~HJO+ +B. pH is a measure of hydronium/hydrogen ion concentration in solution. HA and HB can have the same concentration of hydronium/hydrogen ions in solution since only some of the more concentrated (0.85M) HB acid ions will ionise as compared to all of the less concentrated

I

OR

JiTIIJ II II U-,--,-,. •,

15

Ill•

U

---,-5- lO

lS

~0

~5

51

YI>Mn< of NoOH >
v.&.lmoo/fl.otlo~~·dl'oU

(0.1 mol L" 1) HA.

12

13

The 1r1!orma1kJn COW1ned in 't1ls \locurnl!nt is io!ended for toe proles$lonal asslslaoce olleadling slaft, It OOes not COOSI~llle l!dl'k:e lo s!We!Jis. furlhef ~ f> rot the lnlenlion of CSSA lo pro>ide sped>e markitlg Ollleomes for all posslble Trial HSC ariSWei'S. Rah!r lha purpose Is 1o pro¥lde l!adlefSIIilh infomlalion so thai tile'/ ean bei';Ere:pkl~.llllde!1land at1d iWi HSC ~ requirements, as es~ by !he NSW Bosn1 ct SloJd.fl. No guarantee orW3ffallly b mala or~ w!lh cespeet lo the ~or use of CSSA t.tarl:lng Guldebs in f~ 1o i1trf speci(o; lri3l exam que&fun or answer. The CSSA assumes no ~al:lH)' ot ~pons'Nty for the accuraq, eompl£lelms or us8fuhass o1 any Mac$:lng ~~ prwlded for the Tlla! HSC pa!le!!.

DISCLAIMER The ir!lormal<M coolaim!d In lhls docui!Eilt Is inlellded tor lhe profess:ooal oos!stooce of l!ad!lng stall. t1 does not comtilll!e ii<Mce to s!udenls. FUrllwf RIs not the ln!enUon of CSSA lQ pn:Mr.le speci(.:: ma~klllgOIIIcoines lor a'!~ Trial HSC answers. Raihetlhe pur~eill1o pm-.14Bii!acltefs 'Mtll !olorrnalion so thai tl!eyeanbell« explore, undm\and and i!l-ll!Y HSC martlrig ~lrements, as eslab'!!hed b)' tie NSW Bosnl of Sl~. No~ orwarrantt Is made ori~ v.ilh respect 1o lhe ~!ion or use of CSSI\ ~ ~sIn rdatloo lo any $1)00fiC Ilia! exam qoeslkln or answef. The CSSA assumes no liabi!yorresp:msibiityfof !!'It aecmcy, ~ness or usefulness of any M¥king Gul:!e!kles pMir.led for lhe Trial HSC papers.

DtSCI.A!MER

1

Question 32 (6 marks)

Question 33 (5 marks)

Outcomes Assessed: HJ, H3, H4, HB

Outcomes Assessed: H4, HJ3, H14

~

-·

-~--....

....

.,

...............

~-··-~·

-

,; "'

~

•

Criteria Identifies and thorou2hlv analvses TWO significant imoacts on societv Outlines TWO significant impacts on society

• •

Identifies and thoroughly analyses ONE significant impact on societv Identifies TWO significant impacts on society

•

Outlines ONE significant impact on society

•

Mark 5-6

OR

1-2

Sample answer: The Haber-Basch process has had two significant impacts on society since its invention in the early part of the twentieth century. The first impact was realised soon after its discovery in that it providing the nitrogen compounds needed to make explosives for the Gennan war effort during WWI. The second more sustainable impact has been the provision of ammonia for fertiliser production that has helped to increase crop yields and reduce world hunger. Through the 1800's, heavily populated countries in Europe such as and Britain used guano from islands off the coast of Peru and saltpetre from Chile as a source of nitrogenous compounds. By the end of the 19th century these sources of fixed nitrogen were running out. Scientists were challenged to come up with a process of making fixed nitrogen from the nitrogen in the air. The Haber-Basch process made this synthesis of nitrogen and hydrogen into ammonia cost effective and efficient and was quickly established in several factories in . For a brief time the first factory turned out fertilizer, however, with onset ofWWl, needed munitions for its war effort. To make it worse, the Allies had blocked German supply to the South Ame"rlc3.n saltpetre. The German factories were seconded to provide the nitrogen compounds needed for munitions and the war effort and are either credited or blamed with greatly prolonging WWI and making WW2 possible. Approximately 83% of industrially produced ammonia is used to make fertilisers today. When applied to soil, it helps provide increased yields of crops such as com and wheat. All plants need nitrogen to make amino acids, proteins and DNA, but the nitrogen in the atmosphere is not in a form that they can use. Nitrogen fixation is the name given to any process by which nitrogen (N2) in the atmosphere is converted into ammonia. Atmospheric nitrogen is relatively inert and it does not easily react with other chemicals to form new compounds. Fixation processes free up the nitrogen atoms from their diatomic form to be used in other ways. Nitrogen fixation is essential for all forms of1ife because nitrogen is required to biosynthesize basic building blocks of plants, animals and other life forms such as nucleotides for DNA and RNA and amino acids for proteins. Nitrogen fixation through the Haber process is essential for agriculture and the manufacture of fertiliser, as the ammonia acts as the precursor to various ammonium salts such as ammonium nitrate and sulfate that provide usable nitrogen to plants and then to animals. Using fertilisers to grow plants accelerates growth and increases crop yields. In this way, the Haber-Basch process has had a significant positive impact on society and still does by improving crop yields through the use of fertilisers and reducing world hunger.

~~I I

I

.uu••~·

,.,-..,

•

Criteria Discusses all aspects of water quality using the data Assesses the quality of the water Explains how the water was most likely compromised Explains treatments to make the water-Suitable for drinking Discusses some aspects of water quality using the data Outlines how the water was most likely compromised Outlines treatments to make the water suitable for drinking Discusses ONE aspect of water quality

•

Outlines J:tow the water was most likely compromised

•

Outlines treatments to make the water suitable for drinkin~

• • • • • • •

3-4

OR

,.. • ..,,.. "" ..,,
Till! 11~ con!aloed In Hs document Is inlel\dEd fol die ~ asslslalce o1 leadllng sial!'. It OOes oo1 conslilule advice b sludeniS. FL1111iet k ls flt'l. Ule tmool!on o1 CSSA 1o protide speck marl!klg outoomes fol a1 pos~ Trial HSC iitiSWetS. Ralhef the purposa Is lo provida leachets with irlroonalion so that toe)' r:3ll 0011& explol8, undeiS!and and apply HSC mariilg r~. as estMt;sher:llly die NSW Board or SI!Des. No gu;vantee ll(Willflllltyl$ made or fnpfed ri'l raspectlo ~ ~ ()( ure or CSSA Marijrlg Gr#Jelines in rel3!1on 1o my~ lrbl exam qwstion ()( io'ISWef. The CSSAl!SS'.I'neS no ii!liilyorre$~tyforltlr!aceuraey,~llfiiS!l~olati'JMa~Giidefirlesprzyl.
5

3-4

OR 1-2

OR

Sample answer: The previously yearly average figure shows the average over the preceding year so can be used to compare each water quality factor over the seven-day period. The pH and iron, aluminiwn, nitrate and phosphate concentrations in this tmtreated water are all relatively stable over the seven-day period and very close to the previous yearly average for each factor. In considering these factors alone, the water is within acceptable limits for untreated water and not compromised. However, when considering the E.coli numbers they increase significantly above the previously yearly average from Day 3- Day 7. There is also an increase in turbidity above the previous yearly average for the same day range. The presence of E. Coli compromises the quality of the drinking water significantly as it is a microorganism that causes gastrointestinal diseases with symptoms of vomiting and diarrhea. E.coli at these levels in the water renders it undrinkable. The most probable cause of the increase in E.coli was been the discharge of untreated sewage into the water. This would also for the slight increase in turbidity over the same date range. Flocculation and filtration treatments would remove dissolved and suspended solids and produce clearer water for drinking. Sanitation involves the addition of chlorine, often as sodiwn hypochlorite. The hypochlorite ion, ocr, would kill the E.coli while ammonia is added to keep the water disinfected until it reaches households and businesses. If the treatments have been effective, further testing should yield turbidity readings of less than 1 NTU and an E. coli count of zero organisms/1 00 mL, which are the accepted standards for drinking water in Australia.

15

14 OISC!.AIMER

Mark

DISClAIMER The lnrormallon ront1lned 1o fils drxtJment Is lnleOOed rot t1e professiooal assls!ance olleacl!l!lg 51aft. Hdoes not ~ole arMce lrl slllde!lls. Fur'tlef k Is not llle lnletllion of CSSA 1o p!IM:Ie ~pede mMlrlg Ol.llcomes fol all posslb!e Tilal HSC - s . Ra!llef llle purpose Is lo jlRI'ti!la leacbei's will\ informdlioo so tllallhey r:at1 be!tet expia(e.ll"ldeiS!and and awl~ HSC IJIOOJog~. as~byU!eNSWBoa«<

Q/Siu!.ies.

No !jlliiOIIIee orwar1aoty is m!lde or~ with~ 1o 111e ~ or use or CSSA Uai1.ilg Guldeflle,s in~ lrl my spedf.e ~~exam quesfm or answer. The CSSA i!S$11!'laS no ~orre~follh!rfi:CXI!I:j.~or~Mftlloesso/anyMal:iri,!Guldef.tl&spta\idedklrllleTrlalHSipel's.

(a) (iii) (5 marks) Outcomes Assessed: H3, H7, H8 1 ar~ecea rertOrmance .»anu:;; J-J

Section II Question 34- Industrial Chemistry (25 marks)

•

Criteria Outlines a comprehensive list of the conditions used in the conversion of SOz to S03 AND assesses these in regard to equilibrium and rate considerations Outlines a comprehensive list of the conditions used in the conversion ofS02 to SOJ AND relates these to equilibrhun and rate considerations Outlines a thorough list of the conditions used in the conversion of SOz to S03 AND relates these to eauilibrium and rate considerations Outlines a general list of the conditions used in the conversion of S02 to S03 AND identifies eauilibrium and rate considerations Outlines a limited list of the conditions used in the conversion of SOz to 803

•

Identifie~ eauilibrium and rate considerations

(a) (i) (2 marks)

Outcomes Assessed: H7, H13 ... ...

...~

.....

~·

•

,,. .......................... ,.,--y

Criteria Discusses three properties of sulfur important for the extraction of sulfur by the Frasch oro cess Discusses one or two properties of sulfur important for the extraction of sulfur by the Frasch process

•

•

Mark

•

2

•

1

•

Sample a11swer: The Frasch process involves mining sulfur by forcing superheated water into underground deposits of sulfur thereby bringing it to the surface where it can be collected. There are three important properties of sulfur that enable this process to work. Firstly, sulfur has a melting point of 113°C, which means that the superheated water (usually at around 160°C) is able to melt it. Secondly, the nonwpolar nature of sulfur means that it does not dissolve in the hot water, but instead forms an emulsion that is easily separated and allows for easy recovery of the sulfur. Finally, the low density of sulfur means that it can be brought to the surface along with the hot water by pumping compressed air into the system.

OR

• •

~·

A-·

~····

..··-- -~....... 0 -

Criteria Identifies at least two environmental considerations AND makes an evaluation Iden!i_fies at least two environme!J,tal col!§!deratio~

Mark

2

1

Sample a11swer: The main environmental considerations to be aware of as a result of the Frasch process are possible air and water pollution and the potential for subsidence. Sulfur may be converted to sulfur dioxide or hydrogen sulfide by oxidative or reductive processes which result in gases which are serious air pollutants. Both have unpleasant odours and can adversely affect health. There is also a risk of-contamination of waterways if the water used to extract the sulfur escapes before appropriate treatment. This water will often contain impurities such as heavy metals dissolved out of the underground deposits and so care must be taken to ensure that untreated water does not escape to the environment. Finally, the removal of underground material can leave the area vulnerable to subsidence. While the extraction of sulfur by the Frasch process has inherent environmental risks, these are able to be overcome by suitable monitoring and enable an important resource to be obtained.

5 4 3 2

1

Sample answer:

(a) (ii) (2 marks) Outcomes Assessed: H4, H8

--·

Mark

,

The conditions used for the industrial conversion of sulfur dioxide to sulfur trioxide as part of the manufacture of sulfuric acid are a pressure of one atmosphere or just over, a small excess of oxygen, a temperature of between 400°C and 550°C and a vanadium 01) catalyst used as V20s. From the equation it is evident that 3 mole of gaseous reactants form 2 mole of gaseous product. This would suggest that a maximmn yield would be obtained by using a high pressure. However, this is expensive to achieve as the expense of building a plant capable of maintaining high pressure is costly and the energy input required to maintain high pressures is also prohibitive. A small excess of oxygen is used to promote conversion to products. Le Chatelier suggests that increased concentration of reactants will favour the production of products. While the reaction is exothermic in the forward direction, suggesting a maximum yield will be obtained from low temperatures, this would result in a very slow reaction rate. Therefore, the compromise temperauture of 400- 550°C is used which allows reasonable yields to be achleved relatively quickly compared to higher yields over a much longer time period. Finally the use of a catalyst allows equilibrium to be achieved more quickly. While this will not alter the yield obtained at equilibrium, achieving equilibrium at a faster rate makes the overall process more cost effective. As can be seen, the conditions used are not those that will necessarily provide maximum yields for the equilibrium system. However, as they allow yields to be achieved faster and/or at the most economic rates, the conditions used are the most viable and therefore appropriate for the conversion of S02 to S03 •

16

17

DSCLAIMER Th91nformal:ioo too!aloed Jo wts document Is~ !of !he prlie>sronal ass!si¥1C8 of leadllflg slalf.lt does not Ctlt~S!lllle a
DISCLA!MfR The ln~'oo coo!a'flec:l in ~ doctlment is in!ooded for the ~a! assisliii!Cil of leading sla!f. It does not cooslilule l!drice lo sludenls. Fllflhel ~ Is not lila klleolioo of CSSA lo p!'(Mde ~pecl'IC nOOlng ou!Wnes for iill ~ TMl HSC answers. Raillef !he purpose Is 1o ptO'tide le&chefs wifllnfunn;;iion ro that they ean beller explore, uodefs!and ard apply HSC marking requirements, M 15labli'sl!ed bv the NSW Board of Siuda. No QIJ~anlee orwammty Is madeoc imp:!ed with respect 1o the ap¢caiioo or use of CSSA MM:Irg ~s;, nl!otlon lo Bil'f~it'te !rial exam question or answer. Th!l CSSA assumes no

labi!llyorre.spons~forlhel!COJI'i!C'f,~sorusehmessofanyt.!a'i:ingGI.Iidelinespt~loriii!Tria!HSC~

Wabilityor~forthaaccwacy.~ssorr.tSefulr!e$SoiBil'f/krking~esPfll'k!edb'llleTriali-\SC~s.

(c)(6 marks) Outcomes Assessed: H3, H7, Hl3

(b) (i) (5 marks) Outcomes Assessed: H9, Hll .o "'' "'""'".a r::.1 u1 .uuuu... ..--.

-" ut

nuu-~L.c;

•

• •

•

•

Criteria Describes a comprehensive procedure including conditions AND identifies appropriate safety precautions Describes a thorough procedure including conditions AND identifies appropriate safety precautions Describes a general procedure including conditions AND identifies appropriate safety precautions Outlines a limited procedure AND identifies appropriate safety precautions Outlines a procedure

OR

•

5

•

3

•

2

• I

Sample answer: About 6 g of sodiwn hydroxide pellets were weighed and transferred to a 250 mL beaker and 30 rnL of distilled water was added and the mixture stirred with a glass rod m1til the pellets had dissolved. 10 mL of castor oil was then added and the mixture heated on an electric hotplate with constant stirring for 10 minutes. During this time the reaction mixture was carefully monitored to guard against the solution boiling over. The mixture was allowed to cool for 5 minutes and then 10 g of fme sodium chloride was added and stirred. This was then filtered using a Buchner funnel and the solid residue collected for testing. Safety precautions employed were: wearing of protective goggles and rubber gloves during the procedure as the concentrated hydroxide solution is caustic and will cause burns to the skin and potentially serious damage to eyes if in . Use of an electric hotplate to allow for a more even and less powerful heat source than a Bunsen. The mixture was allowed to cool before adding salt to minimise the risk of the mixture boiling violently upon the addition of finely divided solids. (b) (ii) (I mark) Outcomes Assessed: H9, H14 o:;oo:: .. ..o o::• uttuuno..o:: .uuuu...

.,-J Criteria

•

Mark

Correctly identifies that the soap molecule carries a negative charge and that it contains a hydrophobic and hydrophilic end

..o co• u• tnuuo..o::

.UUUU.J• ,..-.,.

Criteria

•

4

Identifies aoorouriate safety precautions

.....~

~•c;u

Mark

I

Sample answer: Soaps are classed as anionic surfactants because they have a ~ polar and non-polar end to the molecule which allows them to act as surfactants. The polar end carries a negative charge, hence making it an anion.

• •

Mark

Thoroughly discusses three methods of sodium hydroxide production including diagrams and equations identifying technical and environmental issues with each process Discusses three methods of sodium hydroxide production including equations identifying teclmical and environmental issues with each process Discusses three methods of sodiwn hydroxide production including equations for at least two methods identifying technical and environmental issues with each process Discusses three methods of sodium hydroxide production including equations for one method AND identifies technical and envirorunental issues Outlines and names two methods of sodium hydroxide nroduction Outlines and names one method of sodium hydroxide production

6

5

4 3 2 I

Sample answer: There are three co nun on commercial methods employed for the production of sodium hydroxide. These are the diaphragm, mercury and membrane cell processes. All of these cells involve the electrolysis of a brine solution. The diaphragm cell produces large quantities of sodium hydroxide and chlorine, which are both valuable industrial chemicals in sufficient levels of purity and at reasonable costs. However, these plants are no longer built as they have some significant technical and environmental problems. These include the fact that the diaphragm contains asbestos, which is damaging to health through as it can cause cancers such as mesothelioma and asbestosis. The NaOH produced also contains chloride impurities, as the diaphragm is not ion selective. "Chloride ions are oxidised to chlorine gas at the titanium anode (2Cr ---+ Ch + 2e1 and water is reduced to hydrogen gas and hydroxide ions at the iron mesh cathode (2H20 + 2e- ---+ H2 + 20H1. The mercury cell overcomes the problem of chloride contamination in the sodium hydroxide as well as not requiring the use of asbestos. In these regards the mercury cell is superior to the diaphragm cell but it does have the major drawback in that the cathode is composed of liquid mercury. This inevitably results in the loss of some mercury to the environment that is subject to strict controls. This has also meant that few new mercury plants are being built. Chloride ions are oxidised to chlorine gas at the titanium anode (2Cr ---+ Ch + 2e1 and sodium is reduced to sodium metal at the liquid mercury cathode (Na+ + 2e----+ Na). The sodhun and mercury form an amalgam that then es through more water where the sodium reacts with it (2Na +2H20-+ 2Na0H + H2). The sodium hydroxide solution is then crystallised. The third cell is the membrane cell. This is similar in design to the diaphragm cell except that instead of a diaphragm using asbestos, the membrane that separates the anode and cathode is made of a polymer, polytetrafluoroethane. This cell avoids the envirorunental problems of asbestos or mercury use and also allows for the production of high purity soditun hydroxide without contamination by chloride ions. This ion selective membrane allows only positive ions to through it and not negative ions. For these reasons, new plants that are built are likely to be of this type and many producers are gradually replacing old style diaphragm and mercury plants with this new technology. Chloride ions are oxidised to chlorine gas at the titanium anode (2Cr -+ Ch + 2e1 and water is reduced to hydrogen gas and hydroxide ions at the iron mesh cathode (2H2 0 + 2e--+ H2 + 20H").

19

18 DlSClAIMER The f@rrmlioo IXllllaloo::l in !li1s dDcurnetll Is inlenOOd lor lhe prolesslooil asslstonce of teaching $tall. !I dDe5 not COIISl~llle a!Mce lo s!Uc!mts. Flllhf not Vle !Mefltion of CSSA to prO'IIde spedlir:: IIWQ\g ~ lor all posstie Trial HSC ill-rs. Ram lha Jll!fiiOS
-Is

OISCI.AlMffi

The Jnlo«na(on ~In lhl5 docl.lmellt is lnleMed Jrx !he professlooal as.slslance d leadlltlg slalf.lt does IIOli:OIISlilule acM:e lo slOOel!ls. Flh'VIer ~Is rot lbe ldetltion ol CSSA to pmWie $fiE'Ck tmiklng Ollkolnei lor a1 possble Trial HSC aiiSWefS. Ralher IIlii p~~rpose Is 1o ~ ~ l'lilll/liOI~ &I !~~it they can bellet ll);p't;lle, llildefsland and apply HSC ~~as eslabished bytha

NSW Board ol SWes.

No !I'J:1iaolee to'Wa!Cillly Is maGe orlmpierJ 'llilh resped ID lha ~or use of CSSA Matkilg Gulde&les In r1!1a!l01! to~ speck ~ria! exam question to' answe~. The CSSA asS~.meS no ~~yorrespootibililylorlbaaccwacy,~ss~UW"uklessofatlyMai-Jr,g~~forlheTri

(d) (4 marks) Outcomes Assessed: H7, H8, H13 .t.urxeu:u rcrJurmunce Dunm;

Question 35- Shipwrecks, Corrosion and Conservation (25 marks)

(a) (i) (3 marks)

•~J

Criteria

•

•

Provides description of both processes including all chemical reactions Provides a description of both processes including some chemical reactions Provides a description of both processes

•

Provides a description of one process AND appropriate reactions Provides a description of one process

•

Provides an appropriate reaction

•

..OR

Outcomes Assessed: H2, H8, HJ3 1arf!etea rer_formance 1Janas: .J-:J

Mark 4

• • •

2

OR

Criteria Thorouehlv describes the chemistrY ofrustine with reference to chemical eauations Outlines the rusting process using at least one chemical ~~mation Describes the rusting process without the use of chemical equations

3

Crystals of sodium hydrogen carbonate form as they have a low solubility in the anunoniacal brine. This also drives the reaction to the right and increases the yield. The crystals are washed down to the bottom of the tower where it is ice cold and then vacuum-filtered. The filtrate contains a solution of anunonium chloride. This part of the process needs to be cooled as the dissolution of ammonia in water is exothermic. The overall reaction is: NaCI(a,Y + C0 2(g) + NH,(a,Y + H 2 0(/) -> NaHCO,(s) + NH,CI(s) Step 2 involves heating the sodium hydrogen carbonate so that it decomposes to form solid sodium carbonate. Carbon dioxide and water are also produced at this stage with the carbon dioxide being collected and returned to the Solvay Tower for further reaction. 2NaHCO,(s) -> Na2CO,(s) + CO,(g) + HzO(g)

2

I

The rusting of iron is an electrochemical process that begins with the transfer of electrons from iron to oxygen. The iron is the reducing agent (and is oxidised) while the oxygen is the oxidising agent (and is reduced). Separate areas of the iron nail act as both the anode and the cathode. At the cathode site oxyge.ti is reduced to hydroxide ions: 0 2 + 4e- + 2H20 ~40ft. At the anode site, iron is oxidized to iron (II) ions: Fe~ Fe2+ + 2e-. The overall equation for the reaction is:

• '

4Fe + 30, + 2Hz0-> 2Fe,0,.2H2 0 (rust). (a) (ii) (2 marks)

Outcomes Assessed: H2, H8, Hl4 .I arl!ecea rerTormance Danwi; :J-'1 Criteria Identifies and s for a factor that affects the rate of corrosion .~.. States the effect of an identified factor that chan!!es the rate of corrosion

•

Mark 2

I

Sample answer: Lowering the pH of the water by addition of hydrogen ions would accelerate the corrosion of the iron nail. Hydrogen ions are then also reduced at the cathode (2H'" + 2e- ~ H 2) and this greatly increases the rate of corrosion.

(b)(i)(2 marks)

Outcomes Assessed: H7, H8, H12 .l

• •

urJ;:eteu reqvrmunc:e Dunu;,:. ..__.,

Criteria Identifies a factor and outlines the method used to determine how it affects an electroj:'@is reaction Identifies a factor that can affect an electrolysis reaction

Mark 2

I

Sample answer: The type of electrolyte can affect an electrolysis reaction. Inert carbon electrodes were placed into a U-tube filled with copper sulfate. The electrodes were connected to a power source set at 2 V. A drop of universal indicator was added to the electrolyte at both the anode and cathode. The experiment was then repeated with the U-tube filled with sodium sulfate instead of copper sulfate.

20 OlSClJJMER

The lnlorma~ coolained In Ills ~ Is inleOO!d for tte professlonlll assislil!lal ol ~ slalf. It d.;G$1\01 coosl~ule ild\iee 1o studffl!~. FUI\hef ~ Is not !he ir.leflliJn of CSSA ~ pw,tle ~peci!ic Jl\alk!rg ~ for aJ pos>lb!e Trial HSC ii'ISWelS. Raltlet the purpost~ls Ia ~ leacllets 'llift1 Wortrmlon so 11\al Liley tan belief expklre. IJOOeB!aod and apply HSC ma~klng ~.ases!atli$hed tyfl!l NSW!!oamoiS!Wles. No guaramee Ol:wan'al'l!y Is made 01:~ with respect 1o the app!ica11oo «use oiCSSA Ma~~ ~~relation 1o any~ ~ial eKilm q~ 01: an~. The CSSA assumes oo ia!Mily01: ~ty for !lie acwracy, ~s 01: IJSeM\ess oll!nf M.wklng Guk1e1ine$ proW;Ied ror !lie T~al HSC papers.

'

Sample answer:

I

Sample a11swer: In Step I in the Solvay tower, anunonia bubbles up through the brine and is absorbed by it. Carbon dioxide (from the kiln) bubbles up through the brine and precipitates sodium hydrogen carbonate.

Mark 3

21 DISClA!MtR The information rontooed In ~ dclc:umen! Is inleroed for llle PfO(ess!ooalassls!ooce of teaeiJng starr. ll does not cons!iillle a ide specillc rnarl:lng oolcomeslol' all possible Trial HSC answt!rs. Ratl!ef tile p11rpose Is kl pra.kle 1eac11oo wilh ~ r;o !llat IIley con belief eKpOO!, undei~land and awl~ HSC marklng~as:esla~bytieNSWBrlafdofSl~.

tbguarantee 01: Wttranly Is made Dl' lrr¢ed wi!h respect kl 1M app!icalioo 01: use of GSSA Marijng ~In Jdallon lo any specific klal exam queslioo 01: ilriS'M'(, The CSSA a.sumes oo lfabillty 01: re~lol' ~ ao::uracy, ~neil& Dl' useftllnl!ss of any Mar!\lng G!lkleifres pramed fer 100 Trial HSC papers.

I I

'

'

(b) (ii) (3 marks)

(d) (i) (2 marks)

Outcomes Assessed: HII, H14

Outcomes Assessed: H2, H4, HB, H14 ......... ""' ..,. - ....

~

...

c;~c; .....

"''

..,, .,. .. ,. .. "'

~ .......,.

_,-_,

~

Criteria

• • •

Mark

Justifies why the method in part (b) (i) was used Exolains whv at least part of the method was used Identifies ONE variable that must be controlled

3 2

I

• •

-·

...............................

~~

Criteria Col!!l2_ares the suitabilli.Y._of iron and steel for shi2!Juildi~g Identifies some differences in the properties of iron and steel

Mark

2

I

Sample answer:

Sample answer:

Because of its higher carbon content, iron tends to be more brittle than steel and corrodes more readily, as the additional carbon provides more cathodic sites for corrosion. Carbon steels are the preferred structural material in ocean-going ships because of their corrosion resistance, strength and economical price.

To determine the effect of the change in electrolyte on the electrolysis reaction, all other variables must be kept the same. Thus, the concentration and volume of the electrolyte must be kept constant, so too must the types of electrodes, applied voltage and a consistent volwne of indicator added to

each electrode. The type of electrolyte is the only variable that is changed. The drops of universal indicator are added to each electrode to detennine what gases are being evolved at the electrode - if oxygen is being evolved, then so too are W, so the universal turns red. If however, hydrogen is being evolved, so too are OH- so the universal will turn purple.

(d) (ii) (2 marks)

Outcomes Assessed: H2, HB, H14 .&

•

(c)(4 marks)

Outcomes Assessed: Hl, H7, H13 .1.

• •

• •

u;1

~·~u;

.1.

~~

Vllr
•

Hr

~·~u;

.1.

~r

VI'""'''-~ .uu;10u;~•

,;,-_,.

Criteria Outlines a strategy for protecting the hull of ships from corrosion Identifies a strate2V for orotecting the hull of shins from corrosion

Mark 2

I

,;,-J

Criteria Outlines the contribution of Galvani, Volta, Davy and Faraday to our understanding of electron transfer reactions Outlines the contribution of three scientists to our undersum~ng of electron transfer reactions Outlines the contribution of two scientists to our understanding of electron transfer reactions Outlines the contribution of one scientists to our understanding of electron transfer J:e!lqtions ----------

Mark

Sample answer: Zinc blocks can be attached to the steel hull of a ship to act as a sacrificial anode. The zinc oxidises (corrodes) in preference to the iron and releases electrons. The steel hull becomes the cathode and consumes the electrons supplied by the zinc .

4

3 2

(e) (7 marks)

Outcomes Assessed: Hl, H4, H8, Hl3, H14

I

_. "''

•

Sample answer: Galvani performed a series of investigations on the effect of static charge on the muscles and nerves in the legs of frogs and concluded that animal tissue contained 'animal electricity'. Volta invented a device that could transfer static electricity between objects and also invented the Voltaic Pile, alternating discs of silver and zinc separated by cardboard soaked in salt solution. It produced an electric current in an external circuit and was the first battery ever produced. Davy explored applications of the Voltaic pile. He constructed the largest battery ever built and ed a strong electric current through the molten salts of various compounds (potassium hydroxide and sodium hydroxide) he suspected of containing undiscovered elements. Faraday was Davy's assistant and delved into the quantitative aspects of electrochemistry. Faraday developed laws of electrolysis: that the amount of an element produced by electrolysis was dependent on the quantity of electricity ed through the circuit and the atomic weight of the element and its valency. This is important in industrial applications of electrochemistry.

22 llSCLAIMER The lnb'I'Ml'oo conlalned In Ul!s dowment Is lflleotled for till ptole$sionil asslstooce of teoclllng s!aff. ll does no1 COIISli!ule iiiMce lo Slt.ldooli. Fllfllef k Is no1 fie in(enlio(l of CSSA lo proW;Ie specifre IJI2o'kilg oulcoo".e$ for &l possitfe Trfal HSC answe~s. Raillef llle pli(I:OI& Is to pra.ide leildl!l!S wilh inb'mallon ro 111311h&y tan bell« ~ under5liM and apply HSC m.;rQ,g reQUO"ementi. as esW:6shed by 100 NSW Boird of SIUdies. Noguarante
•

•

~'"'"

.s.

l!f:fl.nlnu;n~.-r::;

.u""""'" .s.-u

Criteria Provides a thorough analysis of the conditions at great depths, discusses the chemistry of the corrosion process and links them to a change in the nature of scientific thinking about corrosion Identifies the conditions at great depths, outlines the chemistry of the corrosion process and links them to a chanee in the nature of scientific thinking about corrosion Identifies the conditions at great depths

OR

Mark

6-7

4-5 2-3

• Outlines the chemistrv of the corrosion oro cess • Identifies the conditions at great depths • OR • Identifies an aspect of corrosion at great depths • OR • Makes a link between the discovery and a change in the nature of scientific thinkim!'

I

23 OSCIJJMER Tba ini:Jtmallon ~ Ill Ns dccumenlls lnlended for llle pr6fesslonal assl$ta'"oce of leaehiflg sta«. Hdoes not coosQI.I!a i11Mce 1o S!Udents. Furlhe' KIs not tile lrllenlioo of CSSA 1o prW.de tpeclflc lllifi:Wlg otKomes for all ~ TJ!a! HSC answers. Raltlef lhe pt.11pose Is lo prO'.Ue leachefs wilh lnlorma!lon w that they can bell« e:pklre, WldeBiand aNI apply HSC ~ requ!IOOiii!IS, as e&!ablisbed by 100 NSW Board of Skms. No gu.li"Billee or worramy Is made or Jmpkd wilhmpect lo till~ wuse ol CSSA MM.Ing GUdelines In re!allon lo ~r ~.<: t1a1 exam quesSon or answer. The CSSA assumes 110 tiabili!yorrespon!lbiityfarlha~,~scrusefu!nessofanyt.torl:lng~providedforlhiiTrlaiHSap!lrs.

Question 36- The Biochemistry of Movement (25 marks)

Sample answer: At great ocean depths like that of the RMS Titanic, seawater would have a temperature of about 0°C, very little dissolved oxygen, and a lower salinity than at the surface. It was these conditions that led scientists to postulate that corrosion would be significantly reduced at these depths. The nonnal corrosion of iron requires oxygen and water at the anode to produce hydroxide ions and the lack of oxygen at great depths would seem to suggest that the rate of this reaction would be reduced. Corrosion is also affected by the concentration of the electrolyte and a reduced salinity due to the low temperature could also be expected to reduce the rate of corrosion. Over many years of study of the Titanic resting site and its artefacts, scientists have discovered new previously unknown factors that are responsible for accelerating corrosion at great depths. Some parts of the wreck were covered by sediment or calcareous deposits (CaC03) fanned by marine organisms, causing differences in aeration of the metal in the wreck. Differential aeration results in the setting up of anodic and cathodic regions on the metal surface and subsequent corrosion. It was no"t expected that the marine'organisnis leaving these deposits would be fotmd at these depths. Low pH conditions due to the high concentrations of dissolved carbon dioxide would also increase the rate of corrosion. The presence of higher concentrations of hydrogen ions facilitates the reduction of dissolved oxygen, as shown: Oz +4ft+ 4e· --7 2Hz0 and accelerates corrosion. Anaerobic bacteria were also found in the corroded hull and were reducing sulfate ions in the seawater instead of oxygen. In acidic conditions, sulfate ions are reduced to hydrogen sulphide and water according to this equation: so,l· +lOW+ se·-? H2S + 4H20. The action of the sulfate reducing bacteria provides the electrons needed for the iron in the ship's hull to corrode: Fe--? Fe2+ + 2e·. The hydrogen sulfide produced is also a weak acid and would lower the pH ofthe water surrounding the wreck and further accelerate corrosion. The discovery of the Titanic enhanced our understanding of sulfate reducing bacteria and the role that they play in affecting corrosion. In addition, many marine organisms were also discovered living •at these depths that were not expected. For these reasons, the discovery of the RMS Titanic significantly changed the nature and direction of scientific thinking in tenns of corrosion in the absence of oxygen.

(a) (i) (I marks) Outcomes Assessed: H8 Tareeted Performance Bands: 2-3 Criteria Identifies the name of the anaerobic process

•

Mark

Sample answer: Glycolysis

(a) (ii) (2 marks) Outcomes Assessed: H9, H8 .l

ur~:eu!.u

rerrormance Danwi; '1-o

Criteria Provides a correctly balanced equation that includes all reactants and products Provides an unbalanced equation that includes all reactants and products

• •

Sample answer: C6Ht206 +2NAD+ + 2ADP + 2Pi

Mark 2

I

--)>

2CH,COCOO- + 2NADH + 2ATP + 2H,O + 4H+

IIG=74 kJ mor 1

(a) (iii) (2 marks) Outcomes Assessed: H7, HIO, H13 A. Ul ,!;t:U::U .l:t:f:JUfHIUftt:t: DU,Uo)O J-'1

• •

Criteria Calculates the number of moles of glucose AND the energy produced Calculates the number of molecules of glucose

Mark 2

I

Sample answer: ngtucose

IIG

=250/180.1559 ~ 1.39 mol ~ ~

24 OISClAIMER

Tte irlfoona~ Clllllaifled in !Ills doclitnenl is ifiWOOed lor Ule pml!lsslooal asslslmce of leac!llng slaff. It does no1. consl~rM! ad'ke Ill s!Weflts. Further ~ is no! !he Jnlen(On or CSSA to piO'II:IB spec:Tc ma1:i1g ~ lor al posm<e Trfal HSC answe~s. RatflEf Ule ~Is lo prOW:!e ~Ndlefs wilh ltlfooMtion so lllal !hey coo bel1tf explom.ll!ldemand and ~ HSC mmng ~. as eslal>listoed by !he NSW 9oa!d of Sludies. No !JU3fanree Of Warranty Is made !lf kr¢edwilh respeet 1o tile~ !lf use of CSSA Marking ~ in relation Ia illlY ~peeific !rial exam question llf answer. TM CSSA as.;umes no fat>lily!lf re:spcr.sN~y lor 11!8 accuracy,~ !lfusef\tooss of aoy Marli:il'l,l Gu'4elin&s ~ lor tile Tria! HSC pajleiS.

1.39 x 74 102.7 kJ

25 DISCLAIMER

Tl'e lcWm!allon oon!ainlld In !his docume.11 Is ~ lor 100 profwiollal asslslaoce olleacting slaif. ll does nol wosliiLIIe OOlite 1o slur:lerT!s. Fl.ll\00 Ris oollhe inlenNon of CSSA IQ proW.1e spedfl:; ~ ~ fol' all possible Tr!al HSC IIIWII'I!fS. Ralhef tile purpose Is IQ pm-.io:!a leachefs with ir.formal'on ro 11131 \hey tall be!ter ~plore, undefstand and apply HSC marking «!q~Jiremeflls, as eslab!i5had byllle NSW lbafd of Slttdlei. No!!Uararllw orwiflanty Is ~m lmpkd 'ltilh respect kl the applica!kln Q( use of CSSA MarWng Guidem\es rn relalion Ill ;fll1"t s~ ~lal exam questioo Of answer. llle CSSA assllil'leS no flabl!ltyor '~ filf 1M act\lflq, COII'¢elenm or ll$elu!ness or any Mming Guklf1ioos provklell b' 111e Trial HSC papets.

(c) (ii) (2 marks) Outcomes Assessed: H2, H9

(b) (5 marks) Outcomes Assessed: HB, H9, H12 .Lut·~c::JC:U

.CCIJUI"UIUIU;;e; .UUnU.'lO

~-J

..... ,

• • • • • •

Describes a valid investigation Names the enzyme and substrate Provides feasible suggestions for improving validity and reliability Describes a valid investigation

Provides feasible suggestions for imorovine: validitv OR reliabilitv onlv

4-5 3-4

... "-'

V>•nKn .. ,._ .LI .. U .. .:Jo ... - ...

Criteria

• • • •

Describes viscosity as a property Relates viscosity to the strength of intermolecular forces Identifies hydrogen bonding and the relative number of hydrogen bonds in glycerol and ethanol Describes viscosity as a property

•

Relates viscositv to the stre11gt}.1. of intermolecular forces

OR

Outlines a valid investigation

OR

•

Names the enzyme and substrate

•

Provides feasible suggestions for improving validity

•

Provides feasible suggestions for improving reliability

OR Sample answer: Set up a series of test tubes containing known quantities of milk and rennin. Heat each of the test tubes to different temperatures and time how long it takes the milk to clot. The validity of the experiment could be improved by using a temperature probe to record the temperature rather than a conventional laboratory thermometer. Also ensuring other variables that affect enzyme activity, such as pH, are also kept constant. Repeating each experiment several times and averaging the times for the milk to clot at particular temperatures would improve the reliability.

(c) (i) (1 marks) Outcomes Assessed: H9

Mark

Criteria

Sample answer: 1,2,3- propantriol

2

1

(d) (i) (2 marks) Outcomes Assessed: H4, Hl3 ~

...

... ......

~

....

V# U
Criteria

Mark

• • •

Identifies glycogen as the storage polymer of carbohydrates Identifies storage locations as the liver and ~U's~le cells Identifies glycogen as the storage polymer of carbohydrates

•

Identifies storage locations as the liver and muscle cells

OR

Draws the structure and identifies the svstematic name

Mark

Sample answer: Viscosity is the resistance of a liquid to flow and is related to intermolecular forces in that the stronger the intermolecular forces, the higher the viscosity. The main intermolecular bonding in both glycerol and ethanol is hydrogen bonding, however, because glycerol has more hydroxyl groups (3) than ethanol (1 ), there will be more hydrogen bonding in glycerol. This means that glycerol will be more viscous.

1

OR

•

._~~M

Mark

Criteria

2

1

Sample answer: Carbohydrates are stored as glycogen granules (a polymer of glucose) either in the liver or in muscle cells.

H

I

H-C-0-H I

H-C-0-H I

H-C-0-H I H

26 OISCI.J..IMER The klfonnation c:orta!r.ed ln lhls doc\lmerills in!anc!ed lor lie pr~al assist.lo'ICII of ~ sblf. It does no1 cons~ iiiMca kJ $1Udenls. Fllllher lt 13 no1 tllllnlenlion of CSSA kl proVde specific making oot:o~nes ror a'f poss!bla Trial HSC ~K~SWeB. Ralller till putpose 15 kl proYde teache!s wilh irlfllmlaOOn oo fhal tley cao teller eJCr;4ole, understa'ld and apply HSC markilg requifeml!!l!s, as eslal::tlshed by Uw NSW l!ooid of Sluo;fies. No guarantee orwarra11ty Is l!lalla or lm¢edwilh respect to Uw iipPiiC3Ilon or L!SII of CSSA ~ G\lklekles 1o relam to "MIY spec;IDc: tiiat exam QU!!:tion or answer. Th!! CSSA asslllll!!S no ~orrll!l~IOI"!heaca~~acy,~orL!SIIf!JileMoiW:fMOlklngGthle&lespr()'o!dejjfOI"IheTOOIHSllP*lfS.

27 otSCLAIMEA lhe ~ Clll\lil!lled 1tJ t1!s do:ument Is l[mt1ded klr lie proless.looal asslslooce ot leachltlg sla!f. tt doos not con.s!ilute advke to studenls. Furlhet RIs not IIIII inlention. of CSSA lo jra.ide speo;lK: ~ ~ lot a1 ~ Tlia! HSC ~. Rat.ef the purpoo81s to Jli1Mia leachas wiM!Infoonafloo oolllat !hey can be-ll« eJqOO!e, lltldllrsla1r:l and iiipp!y HSC marS:lng requifemertls, as eslabiMEd by lie NSW 8oord d Sludles. No guararJteeorw~l5 made or~ 'ltit!ltesped to llle i!jlplic3llan Of ~om~ d C5SA ~ Gui6elMs In relaliDn IG any speck Ilia! exam~ wanswer. Tile CSSA asi!OOI$ oo liabiil1orresponsit.iityfotlllaaccuracy,~~rusafulr.essof~yMJl~~~fottheTriiiiHSapers.

(d) (ii) (3 marks) Outcomes Assessed: H4, Hl3, H14 .1. " '

co&c;u .1. . , ,

ut "'"'"""

.L"''"".,. -.-J Criteria

• •

Mark

Compares the higher energy of fats (lipids) with energy from glucose Describes how both lipids and glucose are broken into Acetyl CoA and produce ATP for muscle action Compares the energy density of lipids and glycogen

•

OR

•

Describes how glycogen and fatty acids can be respired to produce ATP but glycogen store is limited

•

States that glycogen is stored in muscles OR in liver

•

States that elucose or _glyco_gen do not produce as much energy as lipids

OR

3

2 '

I

Sample answer: During exercise, when blood glucose levels drop the glucose polymer glycogen stored in muscles and the liver breaks down to produce more glucose. However, there is a limit to how much can be stored. Glucose therefore does not produce as much energy per gram as do fats (lipids). If more energy is needed the stored lipids are broken into fatty acids and undergo reactions to produce acetyl CoA and proceed through the respiratory cycle. Eating a lot of carbohydrate may allow the body to store its maximum amollilt of glycogen, but the length and intensity of the event will determine how long before the energy from fats begins to be metabolised.

(e) (7 marks) Outcomes Assessed: Hl, H4, H8, H14 .l

urge:u::u re:r urtnunce .ounu.l-; .1.-u

Criteria

• • •

• • •

Mark

Demonstrates extensive knowledge of the biochemical processes that occur in the muscles of a sprinter Describes the impact of these discoveries Makes a sound assessment of the impact Demonstrates thorough knowledge of the biochemical processes that occur in the muscles of a sprinter Describes the imoact of these discoveries OR makes a limited assessment Demonstrates sound knowledge of the biochemical processes that occur in the muscles of a sprinter Describes the impact of these discoveries and makes a limited assessment Identifies a biochemical process in the muscles of a sprinter

• •

OR

1 •

Sample a11swer: Advances in biochemistry have identified two distinct types of skeletal muscle fibre with different structure and function. Type I cells are also called slow-twitch cells or fibres and type 2 cells are called fast-twitch fibres. These two types of muscle cells use different fuels and different stages of cellular respiration dominate their energy production reactions. Type I (slow-twitch) muscle cells contract slowly and steadily and have a rich blood supply and therefore adequate oxygen for use in aerobic respiration. These cells have many mitochondria and obtain most of their ATP by the process of oxidative phosphorylation. The filament structure of these muscle fibres shows them to have fewer contractile filaments. Type I muscle cells are useful in light endurance exercise, such as long-distance running. The top distance runners have a highly developed ability to produce ATP aerobically. They use a variety of fuels, such as glucose, fatty acids and amino acids. Type 2 (fast-twitch) muscle cells contract relatively rapidly. They contain fewer mitochondria and have a reduced supply of blood and therefore oxygen. As a result they mostly respire anaerobically. Type 2 or fast-twitch muscle cells are used in high-intensity athletic events such as the sprint events in swinuning and running. Type 2 muscle cells are primarily anaerobic, using the available glucose and stored glycogen as their energy sources. Some glycogen is stored in small granules in muscle tissue. This glycogen can readily be broken down to glucose-6-phosphate and then to glucose, which is available for glycolysis. The action of type 2 muscle cells requires maximum energy in a short time, and is supplied by anaerobic glycolysis. The formation of lactic acid and the resulting drop in pH associated with this process causes muscle fatigue and cramps. To avoid this, athletes follow a training program in order to maximise their bodies' ability to take in and use oxygen. Athletes also have a carbohydrate-rich diet, eating large quantities of pasta, bread and fruits in preparation for their events. Advances in biochemistry have improved our understanding of the structure and function of type 1 and 2 muscle fibres and those factors affecting the performance and maintenance of type 2 fibres used more conunonly for sprinting and short distance rlUUling. For this reason, advances in biochemistry have had a significant positive impact on the performance and recovery of sprinters .

6-7

4-5

2-3

I Identifies 1111 impact

28

IXSCI.AIMER The loro!matioo COI'Jiained Ill Ills doct.menlls lnleMed b' llle professional assis!anc:e of leachlng s!a!f.lt does f\01. consliMe adVice 1o skldenls. FUII!ler KIs r.ollhe inWfiL<Jn of CSSA 1o pm;:l9 speOfJC ~ oulcomes b' aJ possi!Ml Trial HSC ~ ~t.er tile purpose Is lo prO\ti!t leachm ~ !nlclrmalion so that lhe1 can betler expbre, ll!lde!sland 111\d ~ HSC ~ feqWemenis, as~ by 1M NSW 9ootd of Stuclies. No guaranlee orwa«anlyls made or Impled llil.h respec;~ !o lhe ~ Of use of CSSA !.Ia"~ Glllde!ines Ill r«.oo 1o any specific lrlal exam quesl.'on or armrer. The CSSA assumes no iabiMy orresponslbiiitt ror 111e acwracy, comp~e~eoess Of IISefu!ness of arrt Ma-king Gulde!lnes pra.ided tor 111e Trial HSC pafJefS.

29 DISClAIMER The In~ ronlini!d In Ul!s
Question 37- The Chemistry of Art (25 marks)

Sample answer: Since each ion of a transition metal in a different oxidation state has a different arrangement of filled and unfilled 3d and 4s orbitals, they will have different energies they can absorb from the range of visible light, so this will give them different colours. This explains why manganese changes its colour from purple to colourless as it moves from an oxidation state of+7 to +2.

(a) (5 marks) Outcomes Assessed: Hl, H2, H6, H7, H14 -" ...

• • •

................

.,. , .... u ......

-"'~

..........- ...

Criteria Analyses the position of the metal in of ionisation energy, electronegativity and electron configuration Relates the position of the metal in tenns of TWO of the following: ionisation energy or electroneeativitv or electronic confi.l!lll"ation Relates the position of the metal to ionisation energy OR electronegativity OR electroilJc: C:<.?nfi&!:!ration

Mark 5

(c) (i) (1 mark) Outcomes Assessed: H6

3-4 1-2

(b) (ii) (2 marks) Outcomes Assessed: Hl, H6 -"

• •

(b) (i) (1 marks) Outcomes Assessed: H6 Criteria

Mark

•

Sample answer: Manganese

........ ~

.£0'~11~

... ... - ...

Criteria Describes the process required to produce a paint, including the addition of the mineral to a mediwn in which it is insoluble Identifies an example of a liquid mediwn use to produce paint

Criteria

(b) (ii) (3 marks) Outcomes Assessed: H6, H12, Hl3, H14

Mark 2 1

Mark

Outlines a health risk

Sample answer: Some minerals contained metals that were poisonous and could be absorbed through the skin such as mercury and arsenic .

.lU.tgc:u:
•

.. ~ ..... -" . . . . . . . ,

Sample answer: The minerals would have been ground into a fine powder and the powder mixed with media such as plant oils and resins or even saliva. The media rendered the mineral powder insoluble so as to fonn a colloid mixture.

•

•

~~

(c) (i) (1 mark) Outcomes Assessed: H4, H14 Tarl!eted Performance Bands: 2-3

Correctly identifies a transition metal

•

Mark

Sample answer: Green malachite, which is copper carbonate (CuC03)

Sample answer: Technetium (element 43) has an electron configuration of [Kr]3d54s2 and is located in the fifth period of the periodic table. It is in the fifth period because its outer electrons are in the fifth energy level. It is in the d-block (in the second row of transition elements). It is placed in this block because it has a partially filled 4d orbital. It has a first ionisation energy that is much higher than molybdenum (42). This is because it has one electron in each of its d-orbitals, giving it greater chemical stability. It has a lower ionisation energy than ruthenium (44) because the greater the nuclear charge, the harder it is to remove the electrons. Likewise its electronegativity is greater than molybdenum and less than ruthenium. For these reasons, technetium is best placed in between molybdenum and ruthenium.

•

Criteria Name or formula of the stated colour is correct

•

Criteria Links different filling arrangement of orbitals for different ions of the transition metal and hence different energies able to be absorbed, to different oxidation states and to different colours Links simply different colours to different electron arrangements Attributes different colours to different oxidation states

Mark 3 2 1

30

31

Thllilll«~contiliroedlnUllsdoc:l.lnle!lllskllended~lllep!Oiess!ollillas!lsliltlreol!eiidl!ngsla!f,hWesnoiCOMl~ulei!l#lcelos!udenls.furlhefRisnotU!eillklrltOODICSSA!o poW.de specific ma!IOOg ouk:orne$ ~ ail pcmib11J Tml HSC aoswefS. Ralhef file purpose Is lo pr®::le teachers wi«llo~Mna!OO so lhallh&y can bell« explor~. uodeisland and apply HSC lllafking reqWements, as eslablished by ile NSW 8oo«< Dl ~No gt13rot1lee 01:wa111111~ Is made01: ~witt reJiped. lo lfle ~«use or CSSA Marldn;l Guidelltles 1n rel.ll1on lo 211y specifc1MI a:am quesl.'on 01: ili'IS"IIEi. Thll CSSA ~ Jl(l iih'Oiy« responsibiity for file IICCUI&C"/, ~ 01: ~or ooy Marking Guklelil'les proYided !of 1t.e Tllal HSC papets.

OISCLA1MER The ktb'rn3tion IXIIllalned In ~ 6ocurnerd Is kllended for llle ~al asslstanee of leaching sial!. It does not consflula 8<Mca 1o sl!.deols. FIJI!her ills not llle lnlent!«J of CSSA kl p.'O'Iida spedic: ~ 01kcn1es for all posstie Tr~ HSC an~s. Ralhef 1he purpooe 1s 1o pr!Mde leaChtis wiflll'lllrrna*.n SG lhallhey can belief w:plol"e, urdels!aid and awfy HSC ~ requl/ema'lls, as es!ablshed by11le HSW Board D1 Sl
DISCtAIMER

(d) (i) (2 marks) Outcomes Assessed: H6 ..I.Wr

cn:;w.z.

CIJ_IUU,Ufi\.C

LJUUU~o

(e) (7 marks) Outcomes Assessed: Hl, H3, H4, H6, H14 .z. urxc:u:u rt:~Jutnlu.tu~c: .uu.nu,.; ....-u

J-~

Criteria

• •

Defines emission spectra

•

Defines abS..Q!IJtion spectra

Mark

• • • • • • • • •

2

Compares emission and absorption spectra

OR

I

Sample answer: Spectra are produced when electrons in an element transition between energy levels. The lines in the spectrum occur at different wavelengths that represent the energy involved in the electron transition. Emission spectra are produced after an atom absorbs energy and the electron goes to a higher energy level, as it returns to a lower level, it releases energy that corresponds to particular wavelengths shown by the spectral lines. These are seen as coloured lines against a dark background. Absorption spectra however, are formed when white light es through the vaporised element and the atoms absorb energy at discrete wavelengths causing electrons to transition to higher energy levels. Hence wavelengths are 11 missing" from the spectrum. These are seen as black lines against a coloured background.

•

• • •

.... ~ . . ..l

~I

6-7 4-5 2-3

I

Several teclmologies have had a significant impact on the way we analyse pigments that have been used throughout history. These teclmologies have helped us learn about the chemical composition of pigments and allowed for synthetic versions of pigments to be produced that are more stable and versatile than their historical predecessors. Some of these technologies are outlined below. Reflectance spectroscopy is based on the principle that a sample may absorb some photons and reflect others of different wavelengths. The reflected light is collected and measured as intensity as a function of wavelength. A plot is produced showing reflectance against wavelength. Many of the natural pigments used in historical paintings contain transition metal elements that give rise to the colour of the pigment, e.g. Cu, Fe, Zn and Co. The oxidation state of the element and the ligands bound to it determine the colour of the pigment .. Reflective spectroscopy is useful to identify pigments as it does not require the extraction of a sample of the painting and is a non-destructive technique. Infrared reflectography is a specific form of reflectance spectroscopy. It uses infrared radiation (wavelength range of700 run -1 mm). The technique is particularly sensitive to any underlying drawing in graphite, charcoal or black ink, thus giving clues to the artistic process. Infrared radiation is also useful in identifying copper-containing green pigments and therefore helps to detect the presence of these pigments. Ultraviolet-visible spectroscopy, which uses wavelengths in the range of200-700 run, operates on the same principle. Identification of pigments can be made by comparison of the obtained spectrum to those from known standards. Laser microspectral analysis uses a high-energy pulse of laser light to vaporise a small portion of the painting. This vapour is electrically excited, resulting in the sample emitting radiation that is collected as an emission spectrwn. The ability of spectroscopic techniques to determine what pigments artists used in their paintings during history has greatly helped our understanding of the artistic process as well as providing a means for developing more stable and versatile synthetic pigments.

U'l ........... ~ .UW.HM .. • _,-_,

Criteria Explains how careful observation of the spectra of elements both ed AND hindered the complete acceptance of Bohr's atomic model Explains how careful observation of fue spectra of elements ed OR hindered the complete acceptance of Bohr's atomic model Identifies that spectral lines are caused by the movement of electrons from one energy level to another ------

Mark

Sample answer:

(d) (ii) (3 marks) Outcomes Assessed: Hl, H6 A"''

Criteria Sound knowledge of the range of pigments used throughout history Extensive knowledge of how technology has increased our understanding Makes an assessment of the impact linked to criteria Sound knowledge of the range of pigments used throughout history Thormmh knowledl!e of how technolm!v has increased our understandinl! Sound knowledge of the range of pigments used throughout history Limited knowledge of technology Identifies a range of pigments used OR Identifies a technolo~y

Mark 3 2

I

Sample answer: Line emission spectra ed Bohr's model because it was evidence for electrons moving between discrete energy levels and emitting or absorbing energy as they did so. However, further analysis of spectra using more accurate instrumentation found that single emission lines could be resolved into several lines -this could not be explained by Bohr's model. Also, the observed line spectra did not agree with Bohr's model when more than one electron was present, i.e. all elements except hydrogen.

I'

~e

32

33

The informakln contained in tis document Is inl«<ded for lhe ~sb'lal asslslaoce of ~ stall. ll does not constillffl adlice 1o s~ Fufll1et RIs notlhe inloollon of CSSA 1o proWle 5pl1dic ma~ka".g oulc:omts for al poostle Tllal HSC answm. RaiJ1ef lhe p!.lfpore!s to prO\'kle lea:flefs willllnrorlfl3!lon so lila! tley can beller explore, Ul"ll!erslarld and apply HSC 1113!kl\g requll'ements, as Mlatfslled by toe NSW Boald of s~ N!)guarifllee or warranly!s made or!mpJed wllh re!ped lo !he app!"calior! or use Dl CSSA Mmlog ~in rei*Jlo any ~pecllc trial exam queslloo or :lfiS'III'lY. The CSSA assumes no latililyor ~for !he acctlfacy, comp!etene:ss or usefllhess o1 any Marktlg G
Thll inlllrmi!Wo oootail\00 ill this documenlls Jnl£nded Jot 1119 prolesslooal asst!lance oll!!.Khing slolf. ll dws not consJ.ltlle adliu b sludl!flls. Fl.lrther ~ Is nollbe lnlention of CSSA lo piO'I4 spetir.c lll3!k1ng 0\llcomes for aq posmle Tri
DISCLAIMER

DISCLAIMER

Question 38- Forensic Chemistry (25 marks)

(b) (i) (1 marks) Outcomes Assessed: H9, H14 Tareeted Performance Bands: 3-4

(a) (i) (2 marks)

Outcomes Assessed: H9, HJ3 .l JU

• • • •

COJI:O" .l r:;_IJlNUJ"U&.I:O .UUIJ..olo

.>-.

Criteria Identifies the reducine suear as the one with the carbonvl

•

Criteria Describes the relationship between amino acid sequences, DNA and genes Exolains how DNA fmgerorinting can be used to identify individuals Describes the relationship between amino acid sequences, DNA and genes Explains how DNA fingerprinting can be used to identify. individuals

Mark 2

Sample answer:

1

Disaccharide B is the reducing sugar as it is the one that contains the carbonyl group (- C - ).

0 II (b) (ii) (3 marks) Outcomes Assessed: HS, H9, H14 ....... ... ...............

Sample answer: Most cells contain DNA, a complex biopolymer with a very large molecular mass. DNA contains the genes that determine our uniquely individual characteristics such as height, weight, skin colour, eye colour, hair type and so on. Genes are specific sequences of amino acids in the DNA. While genes contain the instructions needed for protein synthesis, there are also portions of a human's DNA that are unique to each individual. These DNA sections can be used to develop DNA fingerprints that can be linked to a particular individual. This process is used both to identify a criminal suspect and to clear innocent suspects by taking samples of DNA from crime scenes and comparing them to the DNA of suspects.

~-~-

~·

~

...........-

-

~

• • •

Criteria Identifies the reagent as Benedict's solution Outlines a procedure for the test including the positive result Explains the chemistry behind the positive result Outlines a procedure for the test including the positive result Exulains the chemistrv behind the positive result Identifies the reagent as Benedict's solution

•

Outlines a procedure for the test including the positive result

•

• •

Mark 3 2

OR

(a) (ii) (2 marks)

1

011tcomes Assessed: H4, H9, H14 .l Ul

• •

•

I:OJI:OU .l 1:01

Sample answer:

Ul ll"lUIO&.« .UUU .. .>o ' 7 - J

Criteria Describes similarities and differences between the DNA of each individual Makes a conclusion about the identity of the child's father Makes a conclusion about the identity of the child's father based on some evidence from the DNA

OR

•

Mark

•• J ..

Reducing sugars may be readily identified by their reaction with Benedict's solution, which is a weak oxidising agent. Benedict's solution, an alkaline solution containing Cu2+ ions, reacts with the carbonyl group of reducing sugars when gently heated to produce a red precipitate of copper(!) oxide. The carbonyl group in the reducing sugar is oxidised to a carboxylic acid group. The characteristic brick-red colour of the copper(!) oxide precipitate is readily observable.

2

1

Describes similarities and differences between the DNA of each individual

(c) (i) (3 marks)

Outcomes Assessed: Hl, H3, Hl3

Sample answer: If a child's DNA profile contains bands that are present in neither the mother nor the supposed father's DNA profiles, then the supposed father is not the child's natural father. In this example, half of the child's DNA bands come from the man and half come from the mother. The child's entire DNA in fuis sample is either from the mother or the man so it is likely that the man is the father of the child.

...................

• • _'!

~·

................ ~ .u-.............. - ....

Criteria Explains the operation of a mass spectrometer Outlines the operation of a mass spectrometer Identifies at least 011,e key point in the oper~"liQ!l_Qf!!.JlUlSS spectrometer

_

.

Mark 3 2 1

Sample answer: In mass spectroscopy the sample is vaporised and bombarded with a stream of high-energy electrons. The resulting negative ions are discarded and the positive ions are accelerated by an electric field and then ed through a magnetic field. This causes the ions to move in curved paths in which the radius of the path depends on the charge/mass ratio of the ions. The result is that the ions are detected in different positions according to their relative charge/mass ratio. The masses of the ions can be calculated and the intensity of the reading determines their abundance. 34 OISCI.AIMER

lhe infor~ conti!lood Jn WS dorunefll!slnlended for 1he Pfolessloool ii$$1sliillCe olleacl'll(,g slalf. It ®as 1101 ~!iiWI ad"ke k1 s~ F~ a Is not tile !nlrolion of CSSA to PfO\Iide spedfic marking DUlalrnes for ail poss..t~e TiiG! HSC ar.swers. Ratllef 1he purpose Is 111 J.lfO\'de l!ach£fs l'oi!h ~ so !1!31 t.ey eM be!lef expbfe. Lll\llemond ard apply HSC marllig requirements, as es~ by tte NSW Board of Studies. No guaranlee 01 W3rtanty Is nl3de or !mptied wilh re~ 1111he ~or use of CSSA. Mall
35 DISCLAIMER lha ~ Ollllalned In Ulls documenl Js lnl!tldecl b" lhe profe.!slonal assls!ance of leachlr.g slalf. I! daes not cm.sUMa advic.a 1o s!UderU. FIKI!ler ~ Is nolllle lnlent'«l of CSSA 1o ~ $peCi&: ll13lking OIIICOme!S b" iii ~ Trial HSC answm. Ralher !he purpos& lslo prll'Me leadler5 Willi ~ so lllallhey can betlet expbra, undersland ard ;wl~ HSC IOOI!dngreqt.lkemoo!S,as~bylheNSWI!ootdofSlcm.

No~ orwarr&'\1)' Is ma®lll' lm¢ed llilh resped Ia tte lli(lplicaiJIX'Ill' use o1 CSSA Ma!t!rijj ~Ill re!a$0n Ia any speQfic: kfol e.wrlqutl$tioll oranswe~:. The CSSA. aswmes no II;K4tyor rupoc~SitH!y for lli
(e) (7 marks) Outcomes Assessed: H4, H9, Hl3, Hl4

(c) (ii) (2 marks)

Outcomes Assessed: H3, Hl4 1 an:ereu renormance na11a5:

.1. art?ecea rerror1nallce DUnCQ·; A-a

q-:J

Criteria Describes the need for mass spectrographs of known compounds Explains how the unknown mass spectrograph is compared to know spectrographs for identification Outlines the use of mass soectr01zraohs in identifvin2 comoounds

• •

•

Mark 2

1

Sample answer: The mass spectrum of toluene shows a peak corresponding to the ion of toluene at rnlz=92 which is its molecular mass. Several peaks due to molecular fragments formed from collisions between the parent molecules and high~energy electrons are also shown at other masses. A spectnun like the one

shown would have been produced with a pure sample of toluene. Comparing the mass spectrum of the unknown sample with the mass spectra of known organic compounds like toluene would allow for the constituents of the unknown mixture to be identified. (d) (i) (2 marks)

Outcomes Assessed: H2, H3, Hl3 .1. un:eu!u

renurmunce DUilus;

:J-'1

Criteria Describes the use of line spectra in forensic analysis using a specific example Describes the use of line spectra in forensic analysis

• •

Mark 2

1

···"" Sample answer: Each element has its own unique spectrum with lines appearing at different wavelengths. A soil sample could be analysed to produce a spectrum that would show lines at many different wavelengths. By comparing the spectrum to of the soil sample to the spectra of different elements, the elements in the soil sample could be identified. (d) (ii) (3 marks)

Outcomes Assessed: H6, H13, Hl4 .I.UTJOC
• • •

Criteria Explains whv each element oroduces its own spectrum Describes spectra as a result of electrons moving from a higher to lower energy level Identifies that spectra are related to energy levels in an atom.

Mark 3

Criteria Effectively corrununicates a thorough understanding of a sensitive analytical technique used in forensic investigations AND • Discusses at least two impacts of this teclmique on forensic investhmtions • Describes a sensitive analytical technique used in forensic investigations AND • Discusses at least ONE impact of this teclmique on forensic investigations

Mark

•

6-7

4-5

OR

• • • •

Describes at least TWO imnacts of this teclmiaue on forensic investigations Identifi~s a sensitive analytical teclmique used in forensic investigations 1-3

AND/OR

Describes at least ONE imnact of this teclmiaue on forensic investie:ations

Sample answer: High performance liquid chromatography (HPLC) is a form of liquid chromatography that was developed in the mid-1970s. Over the past few decades the technique has been improved, allowing for better separation and identification of very similar compounds that are dissolved in solution . HPLC can be applied to the analysis of low concentrations of organic substances such as proteins in envirorunental, food, drug or biological samples. HPLC is used to detennine the amount of caffeine in soft drinks. This method has a shorter flow time than other methods as it runs at high pressures, but it has the advantage of operating at room temperature, so heat-sensitive samples are not degraded. HPLC is useful to forensic chemists because of its high resolution, high-speed scans and high sensitivity. High resolution is important because compmmds of almost identical mass cap. be separated, allowing the accurate and reliable comparison of samples. The impact of this on forensic investigations has been to increase the degree of confidence in results obtained. The high speed of scanning in HPLC is also important because analyses that would have previously required highly skilled chemists to undergo a complex series of tests are now performed in a few seconds. The high sensitivity of HPLC means that samples of only a few micrograms can be analysed. This has had a huge impact on forensic investigations because in the past there were many cases where samples were too small to allow traditional chemical analysis. Today a small portion of a sample may be analysed by HPLC and the remaining sample can be subject to other analytical techniques.

2

1

Sample answer: As excited electrons move to lower energy levels, they emit particular ammmts of energy. This corresponds to a particular wavelength such that the energy is inversely proportional to the wavelength. Since each element has its own unique difference in energy between energy levels, each must also have its own unique corresponding wavelengths and these show up as lines in the spectrum for the element.

36 DISCtAIMER The n~ Clll'lla1i\ed lo ~~ docurnenlls lnlended lof tile professkltlal asslslanre of leading s!aft'. Hdoes not coos!J.!JI9 advice ID sklden!s. Fur'alef n Is not tile 1rl!allJon of CSSA to proWJe Sj)et'ific nmlng OtJI!xlmoo for iri pouilla Tllal HSC !II~ Rat!er tile purp:m l!i lo pmo.;de leachefs wi11t ~ so lhal t1ey cac1 belief expbre, IJII
37 OISCLAIM!:R

The hlo!nlaltOn !XI!IIi!loo:llo Ws l!octlmen! ~ Intended fur lho ~iooal assistartte of leaching s!aff. Udoes OO! ~oosllule ad\ica k:l sludenl$. Fu!U1tl' ~ Is no! lhe lnleoliorl of CSSA to ~ specific IMiilng 0\lleome.s W at possi"ble Trial HSC 91\SWefS. Ralher Ill& porp:~Se l$la ~~ leachm wilh lrlformaL'oo so lhal.lhey can belief ~plore, undelslood and apply HSC mailing requlremenl$, as es!abRsl~Ed by IIlli NSW Board r:l S\udles. Nogvi!l'ar'!!ee orwar/allly Is made orlfl'lp§ed' 'llill'!lespetllo !he applkal!oo or use o( CSSA Mamng G~ In ri!latlcn lo any specl"c ~lal exam ~liorl or anSll'ef. Tile CSSA assll!l1!ls oo liabililyorrespoosibiilyfor lhe aa:uracy, comple\enmor usefllloess r:1 any Marking <.lUidellnes provided for tile Trial HSC pape1s.