This document outlines an experiment involving electrochemical cells. It describes objectives to construct galvanic and electrolytic cells, determine cell potentials, and apply Faraday's law. Procedures are provided to measure voltage of galvanic cells using CuSO4 and ZnSO4 solutions, observe the effect of concentration on voltage. Electrolysis of KI is described to produce I2 at electrodes. Finally, Faraday's law is applied by electroplating a coin and measuring deposited copper mass over time.

1. EXPERIMENT 5
ELECTROCHEMICAL CELLS
GROUP VIII

2. OBJECTIVES
Upon completion of the experiment, the student be able to:
1. construct and setup galvanic and electrolytic cells;
2. determine the cell potential of galvanic cells;
3. determine the effect of concentration of the cell potential;
4. determine the electrode reactions during the electrolysis of
aqueous solution of potassium iodide and;
5. apply Faraday’s Law on the electroplating of a ten-centavo
coin.

3. LIST OF CHEMICALS
 1 M CuSO4
 0.001 M CuSO4
 aqueous potassium iodide
 starch solution
 1 M ZnSO4
 0.001 M ZnSO4
 phenolphthalein

4. LIST OF APPARATUS
 voltmeter/ammeter
 Cu electrode/strip
 salt bridge containing saturated KCI
 pipet
 dropper
 50-mL beakers
 Zn electrode/strip
 electrolysis setup
 test tubes and rack
 ten-centavo coins

5. SAFETY PRECAUTIONS
1. Wear laboratory gown or apron during the entire laboratory
period and safety goggles when doing the experiment.
2. All safety rules apply to this experiment.
3. Dispose chemicals on designated bottles.
Notice to Students and Instructors:
Ten-centavo coins should be brought by the students and
must be assigned 1 week prior to the experiment.

6. WASTE DISPOSAL
1. After the experiment, dispose of the solutions in
appropriately-labeled containers in the fume hood.
2. Do not mix different solutions into a single waste
container.

7. Electrochemical Cells- is a device capable of either generating electrical energy from
chemical reactions or facilitating chemical reactions through the introduction of
electrical energy. There are two basic types of electrochemical cells: those
electrochemical devices that generate electricity from spontaneous reactions are
known as galvanic cells (aka voltaic cells), while those that make use of electricity or
electric current for certain chemical reactions to occur are termed electrolytic cells.
Galvanic Cell- is an electrochemical cell that derives electrical energy from
spontaneous redox reactions taking place within the cell.
Electromotive force (emf)- is the voltage developed by any source of electrical
energy such as a battery or dynamo.

8. Electrolytic Cell- is an electrochemical cell that undergoes a redox reaction when
electrical energy is applied. A common example of an electrochemical cell is
a standard 1.5-volt "battery". (Actually a single "Galvanic cell"; a battery
properly consists of multiple cells, connected in either parallel or series
pattern.)
Electrolytic Cell- is an electrochemical cell that undergoes a redox reaction when
electrical energy is applied. A common example of an electrochemical cell is
a standard 1.5-volt "battery". (Actually a single "Galvanic cell"; a battery
properly consists of multiple cells, connected in either parallel or series
pattern.)
Electroplanting- is a process that uses electrical current to reduce dissolved
metal cations so that they form a coherent metal coating on an electrode.
Electroplating is primarily used to change the surface properties of an object
(e.g. abrasion and wear resistance, corrosion protection, lubricity, aesthetic
qualities, etc.), but may also be used to build up thickness on undersized
parts or to form objects by electroforming.

9. PROCEDURE
I. VOLTAGE DETERMINATION
A. Construction of a Galvanic
1. Place 25.0 mL each of 1M CuSO4 solutions in two
separate 50-mL beakers.
2. Dip a copper (Cu) electrode in the CuSO4 solution and a
zinc (Zn) electrode into the ZnSO4 solution.
3. Connect the two solutions by a salt bridge containing
saturated KCI. (Ensure that each end of the salt bridge is
immersed into each of the solutions.)
4. Connect the Zn electrode to the negative terminal of the
voltmeter and the Cu electrode to the positive terminal.
5. Allow the cell to stand for 3 minutes and read the cell
potential as well as the temperature of the solutions.

10. B. Effect of Concentration on the Cell Voltage
Repeat the procedure describe above, this time using the following
Pairs of solutions:
1. 1M ZnSO4 and 0.001M CuSO4
2. 0.001M ZnSO4 and 1M CuSO4

11. II. ELECTROLYSIS OF AQUEOUS POTASSIUM IODIDE
A. Electrolytic Cell Set Up
1. Set up the electrolytic apparatus shown in Figure 5.3 using aqueous potassium
iodide as your electrolyte.
2. Use only enough electrolyte solution to fill the tube just above the bridge
connecting the two test tubes.
3. Mark the electrodes as X and Y.
4. Connect electrode X to the negative terminal of the battery and electrode Y to the
positive terminal.
5. Complete the circuit and allow electrolysis to proceed.

12. B. Electrolysis of Aqueous Potassium Iodide
1. Break the current after visible changes are observed.
2. Carefully remove the electrodes.
3. Simultaneously draw out about 2 mL of the solution at each electrode and place
into two marked test tubes.
4. Draw out another set of 2 mL solutions at each electrode and label them properly.
5. To the first pair of liquids drawn out, add 2 mL of starch solution to each test tube
and shake for about a minute. (Molecular iodine (I2) forms a complex with starch
producing a blue solution.)
6. To the second set of solutions drawn, add 3 drops of phenolphthalein to each of the
test tube. Observe any color change.

13. III. FARADAY’S LAW AND ELECTROPLATING
1. Polish a ten-centavo coin and a strip of copper properly.
2. Measure the mass of the coin and the copper using a top loading balance.
3. Prepare 30 mL of 1.0 CuSO4 solution in a 50-mL beaker.
4. Set up the apparatus and ensure that the copper strip is connected to the positive
terminal (anode) and the coin to the negative terminal (cathode) of the 6V battery.
5. Start timing the electrolysis once the coin and copper strip is immersed and the
circuit is complete.
6. Allow for electrolysis to proceed for 15 minutes. Record the amperage every 3
minutes.
7. Remove the copper strip and the coin after 15 minutes and allow these to air dry.
8. Measure the mass of the coin and the copper strip when completely dry.