Electrical Conductivity Of Electrolytes And Non - Electrolytes 2j4f72

: 07-07-14

Experiment no. 7 Electrical Conductivity of Electrolytes and Non-electrolytes

Guillermo, Janina Suzette C. Escudero, Angela Julia R. De La Salle University – Dasmariñas Dasmariñas, Cavite Philippines

ABSTRACT

In this experiment, we observed the electrical properties of solutions and conductivity of the reacting systems. For the electrical properties of solutions, reagents were placed in 100mL beakers and are tested for electrical conductivity by dipping the electrodes into the reagents by using an electrical conductivity apparatus; the electrodes were washed with distilled water and dried before submerging it again into another reagent. For reacting systems, same procedures are done but the two solutions are tested for the conductivity of the mixture off 1 M of ammonium hydroxide and 1 M acetic acid. Electrical properties are observed and identified as electrolyte and non-electrolyte, intensity of brightness (bright/ dim/ no light), and strength of electrolyte (weak or strong). All methods used were effective in observing the electrical properties of solutions and conductivity of the reacting systems.

INTRODUCTION Electrical properties are dependent on the number and nature of the charged particles within the solution, which move between electrodes under the influence of an electric current. Some solutions exhibit electrical properties. Electrolytes are substances whose aqueous solutions are capable of conducting an electric current. On the other hand, non-electrolytes are electrically non-conducting in a solution and do not form ions. Electrolytes that produce positively charged ions are called cations and the negatively charged ions are called anions when they are dissolved in aqueous solutions. Strong electrolytes are classified as those that are completely or almost completely ionized, while weak electrolytes are those that produce comparatively few ions. Brightness is affected by how strong the electrolytes are, and are distinguished as bright light, dim light and no light.

MATERIALS AND METHODS

In determining the electrical properties of a solution, we have used different reagents to test whether a solution is an electrolyte or non – electrolyte. The following reagents are Distilled water, Tap water, 12 M of HCl, 1 M of HCI, 1 M NaOH, 1 M NH 4Cl, 95% C2H5OH, 1 M NaCl, Conc. H2SO4, 1 M

H2SO4, 17 M CH3COOH, 1 M CH3COOH, Sodium chloride (crystals), Sucrose (crystals), and 5% sucrose solution. Each reagent was placed in a separate 100mL beakers at about 1/3 full. Next, prepare the conductivity apparatus with a lighting bulb and two electrodes. These electrodes will be soak in each reagent and the bulb will emit a light depending on the electrical property of the solution. As the bulb emits light, Observe the brightness if it has no light, dim light or bright light. After soaking the electrode, wash the electrode with distilled water inside the wash bottle before dipping them into other samples to avoid reactions between reagents. To determine the electrical conductivity of reacting systems, prepare 6mL of 1 M ammonium hydroxide in a 50mL beaker and place also an equal amount of 1 M acetic acid in another 50mL beaker. Test the conductivity of each reagent using the conductivity apparatus and again determine the intensity of light it emits, as the electrode was soak into the solution. Next, mix the two solutions and test its conductivity. In determining the electrical conductivity of a solution depending on the result of the intensity of light, bright light means strong electrolyte, dim light means weak electrolyte and no light means non – electrolyte.

RESULTS AND DISCUSSIONS A. Electrical properties Observation on the brightness of light (no light/dim light/ bright light)

Solutions

Classification (Weak electrolyte/strong electrolyte/nonelectrolyte)

Tap water

Dim light

Weak electrolyte

Distilled water

No light

Non - electrolyte

12 M HCl

Bright light

Strong electrolyte

1 M HCl

Bright light

Strong electrolyte

1 M NaOH

Bright light

Strong electrolyte

1 M NH4Cl

Bright light

Strong electrolyte

95% C2H5OH (Ethanol)

No light

Non - electrolyte

Sodium chloride (crystals)

No light

Non - electrolyte

1 M NaCl

Bright light

Strong electrolyte

Conc. H2S04

Bright light

Strong electrolyte

1 M H2SO4

Bright light

Strong electrolyte

17 M CH3COOH

No light

Non - electrolyte

1 M CH3COOH

Dim light

Weak electrolyte

Sucrose (crystals)

No light

Non - electrolyte

5% sucrose solutions

No light

Non - electrolyte

B. R e a c ti n g

systems Solutions

Observation on the brightness of

Classification (Weak

light (no light/dim light/ bright light)

electrolyte/strong electrolyte/non-electrolyte)

1 M NH4OH

Dim light

Weak electrolyte

1 M CH3COOH

Dim light

Weak electrolyte

Bright light

Strong electrolyte

1 M NH4OH + 1 M CH3COOH

Electrical conductivity is a useful property characterizing a solution as its ability to conduct an electric current. So the crystal sucrose and crystal NaCl did not conduct electricity because they are nonelectrolytes. The extent to which a solution can conduct an electric current depends directly on the number of ions present. There are several classes of strong electrolytes: (1) soluble salts, (2) strong acids, (3) strong bases. And so in the experiment, those that showed bright lights, 1M & 12M HCl, NaOH, NH4Cl, NaCl, concentrated and 1M H2So4, have been classified as strong electrolytes. Weak electrolytes are substances the exhibit a small degree of ionization in water. The most common weak electrolytes are weak bases and weak acids. And so acetic acid and tap water exhibit dim lights in the experiment. Acetic acid is very different from the strong acids because only about 1% of its molecules dissociate in aqueous solutions at typical concentrations and the other 99% will remain intact. This is because weak acids only dissociate to a slight extent in aqueous solutions. So the 17M CH 3COOH was crowding the solutions with excess and the less concentrated 1M acetic acid was able to conduct marginally dim light. Since the dissociation constant is low for both acetic acid and ammonium hydroxide, they do not produce ionic species individually. As for the reaction of ammonium hydroxide and acetic acid,ionic species increase as NH4+ and CH3COO- until one or the other is completely spent. Ionic species in water produces conductivity. As to conclusion, An electrolyte is a substance that, when dissolved in water, produces a solution that can conduct electricity. Electrical conductivity is measured by the ions that are produced in these solutions. There are two classifications that can define electrolytes: strong electrolytes and weak electrolytes. When the substance dissolved in an aqueous solution doesn’t conduct electricity, it would then fall under the nonelectrolytes. In accordance to the Arrhenius Acid-Base Theory, ions were the basis of conductivity and so strong acids and strong bases would become strong electrolytes. Also weak acids and weak bases dissociate less and so are classified as weak electrolytes. Overall, strong electrolytes include: soluble salts, strong acids, and strong bases. Weak electrolytes include: weak acids and weak bases. Nonelectrolytes would be compounds that don’t have either an H + or an OH-.

REFERENCES (1) Samonte J.L, Figueroa L.V General Chemistry Laboratory Manual 4th Edition, C&E Publishing Inc., 2014. (2) Zumdahl, S. (1997). Types of Chemical Reactions and Solution Stoichiometry. In Chemistry (4th ed., p. 137). Boston: Houghton Mifflin.