DETERMINATION OF ELECTRODE POTENTIALS

R.Y.A. RIVERA

DEPARTMENT OF FOOD SCIENCE AND NUTRITION, COLLEGE OF HOME ECONOMICS UNIVERSITY OF THE PHILIPPINES, DILIMAN, QUEZON CITY 1101, PHILIPPINES DATE SUBMITTED: 23 APRIL 2015 DATE PERFORMED: APRIL 2015

ANSWERS TO QUESTIONS

1. Discuss the differences between galvanic and electrolytic cells.

In an electrolytic cell, an outside source of energy such as battery is required for it to work and the

flow of electrons comes from the cathode to the anode. On the other hand, the reaction in a voltaic

cell occurs simultaneously and the flow of electrons comes from the anode to the cathode.

2. What is the measured value of Ecell for each cell and its relevance to the E red for the iron

half-cell and halogen half-cells?

3. Compare the calculated E red for each half-cell with their literature value.

Generally, the calculated Ered values of the half-cells are very close to the book values. Most

of the percent errors calculated were less than 5% meaning, there was only a slight error in the

performed experiment. However, for the half cell Br|Br2 |C, the percent error was 52.32%.

4. Based on your observations, what are the half reactions which occur at the anode and

cathode during the electrolysis?

= .592

[2]

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= .592

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[2]

5. Based on the calculated values, what are the most effective reducing and oxidizing agent?

Zinc is the reducing agent while copper is the oxidizing agent.

6. Are the values of standard reduction potentials helpful in determining the spontaneity of a

reaction?

Determining the spontaneity of a reaction depended on the values of standard reduction

potentials. This means that the farther the value of the standard reduction potential (SRP) of the

half-cell is from the SRP of copper, the more spontaneous the reaction would be. Individually, the

standard reduction potentials of the half-cells, when at a higher value, also indicate a higher

tendency to be reduced and serve as a cathode in the voltaic cell and as an anode in an electrolytic

cell.

7. What are the possible sources of errors and their effect on calculated parameters?

If the multimeter and alligator clips used were not checked before the experiment, wrong reading

values. Also, mistakes in the preparation of solutions can greatly affect the voltage readings.

REFERENCES

Skoog, et al., Fundamentals of Analytical Chemistry, Eighth edition, 2004