Chemistry Assesment 314ps

#47 Give three common ways that matter is measured. Give examples of each

Counting: Example, counting sheep Volume: Example: estimating the # of jelly beans in a large jar. Mass: Example: Weighing out some NaCl.

#48 Name the representative particle of each substance: a. oxygen gas O2 (a molecule)

b. sodium sulfide Na2S (a formula unit) c. sulfur dioxide SO2 (a molecule) d. potassium

K (an atom)

#49 How many hydrogen atoms are in a representative particle of each substance? a. Al(OH)3

3

b. H2C2O4

2

c. (NH4)2HPO4 9 d. C4H10O

10

#50 Which contains more molecules: 1.00 mole H2O2 , 1.00 mole of C2H6, or 1.00 mole CO?

They all contain exactly the same:

6.02 x 1023 molecules

#51 Which contains more atoms: 1.00 mole of H2O2 , 1.00 mole of C2H6, or 1.00 mole of CO?

Since H2O2 contains 4 atoms per molecule, C2H6 contains 8 atoms per molecule, and CO only 2 atoms per molecule; 1 mole of C2H6 contains the most atoms (6.02 x 1023 times 8)

#52 Find the number of representative particles in each substance: a. 3.00 moles Sn = (6.02 x 1023 times 3)

b. 0.400 moles KCl = (6.02 x 1023 times .4) c. 7.50 moles SO2 = (6.02 x 1023 times 7.5) d. 4.80 x 10-3 moles NaI = (6.02 x 1023 times .0048)

#53 Calculate the molar mass of each substance: a. H3PO4 = 98.0 g/mole b. N2O3 = 76.0 g/mole c. CaCO3 = 100.1 g/mole d. (NH4)2SO4 = 132.1 g/mole e. C4H9O2 = 89.0 g/mole f. Br2 = 159.8 g/mole

#54 Calculate the mass of 1.00 mole of each of these substances the mass on one mole of something is just its molar mass… a. SiO2 = 60.1 g/mole b. N2 = 28.0 g/mole c. Fe(OH)3 = 106.8 g/mole d. Cu = 63.5 g/mole

#58 How many moles is each of the following: In each of these you simply divide by the molar mass of each compound

a. 15.5 g SiO2

15.5 g x 1 mole (28.1 + 32)

= .258 moles

b. .0688 g AgCl

4.80x10-4 moles

c. 79.3 g Cl2

1.12 mole

d. 5.96 g KOH

.106 mole

e. 937 g Ca(C2H3O2) f. .800 g Ca

5.93 mole

.020 mole

#59 Find the mass of each substance. In each of these you multiply by the molar mass a. 1.50 mole C5H12 = 108 grams b. 14.40 mole F2 = 547 grams c. .780 mole Ca(CN)2 = 71.8 grams d. 7.00 mole H2O2 = 238 grams e. 5.6 mole NaOH = 224 grams f. 3.21 x 10-2 mole Ni = 1.88 grams

#60 Calculate the volume of each of the following gases at STP.

The volume of any gas at STP is 22.4 liters per mole a. 7.6 moles Ar

x 22.4 liters = 1.7 x 102 liter 1 mole

b. .44 moles C2H6

x 22.4 liters = 9.9 1 mole

liter

#61 What is the density of each of the following gases at STP. (density is in units of grams/liter) a. C3H8

The molar mass is: (12x3 +8) = 44

44 g x 1 mole = 1 mole 22.4 liters b. Ne

1.96 g liter

The molar mass is: 20.2

20.2 g x 1 mole = 1 mole 22.4 liters

.902 g liter

#61 What is the density of each of the following gases at STP. (density is in units of grams/liter) c. NO2

The molar mass is: (14+32) = 46

46 g x 1 mole = 1 mole 22.4 liters

2.05 g liter

#62 Find each of the following quantities: a. the volume, in liters, of 835 g SO3 835 g x 1 mole x 22.4 liters = 1 mole 1 80.1

234 Liters SO3

#62 Find each of the following quantities: b. the mass in grams, of a molecule of aspirin (C9H8O4) 22.4 liters = 1 mole 1 molecule x 1 mole x 1 6.02 x 1023 molecules 180 g = 1 mole

2.99 x 10-22 grams

#62 Find each of the following quantities: c. The number of atoms in 5.78 moles NH4NO3 5.78 moles x 1

6.02 x1023 molecules 1 mole

9 atoms = 3.13 x 1025 atoms 1 molecule NH4NO3

#63 Calculate the percent composition of each compound. a. H2S The total is: (1.0 x 2) + 32.1= 34.1 % comp. H is: 2.0 x 100 = 5.9% 34.1

% comp. S is: 32.1 34.1

x 100 = 94.1%

#63 Calculate the percent composition of each compound. The total is: b. (NH4)2C2O4 (18.0 x 2) +24.0 + 64.0 = 124.0 % comp. N is: 28.0 124.0

% comp. H is:

x 100 = 22.6%

8.0 x 100 = 6.5% 124.0 % comp. C is: 24.0 x 100 = 19.4% 124.0 % comp. O is: 64.0 x 100 = 51.6% 124.0

#63 Calculate the percent composition of each compound. The total is: c. Mg(OH)2 24.3 +(17.0 x 2) = 82.6 % comp. Mg is: 24.3 82.6

x 100 = 41.7%

% comp. O is:

32.0 x 100 = 54.9% 82.6

% comp. H is:

2.0 x 100 = 3.4% 82.6

#63 Calculate the percent composition of each compound. The total is: d. Na3PO4 (23.0 x 3) + 31.0 + 64.0 = 164.0 % comp. Na is: 69.0 x 100 = 42.1% 164.0

% comp. P is:

31.0 x 100 = 18.9% 164.0

% comp. O is:

64.0 x 100 = 39.0% 164.0