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1. If G° = -nFE° and G° = -RT ln Keq, derive the relationship between E° and K,

ID: 963597 • Letter: 1

Question

1. If G° = -nFE° and G° = -RT ln Keq, derive the relationship between E° and K, expressed as Keq =

2. If the reduction of Cl2 to 2 Cl-  has a potential of 1.3583 V and the reduction of K+ to K has a
potential of -2.95 V, write the reaction between the aforementioned species that is
thermodynamically favored.

3. If the reduction of Cl2 to 2 Cl- has a potential of 1.3583 V and the reduction of K+
to K has a potential of -2.95 V, determine the overall E° of the thermodynamically favored reaction.

4. As E° increases, do electrochemical reactions become more or less favored?

5. The standard hydrogen electrode (SHE) is the reference electrode in which 2 H+ions are reduced to molecular hydrogen. This electrode is sometimes written as H2/Pt. Why would platinum berequired for the electrode if it isn’t involved in the reaction?

Explanation / Answer

1)

G° = -nFE°

G° = -RT ln Keq

- n F Eo = - R T ln Keq

Eo = RT ln Keq / nF

2)

2 K --------------> 2 K+ + 2e - Eo = - 2.95 V

2 Cl- + 2e- -------------> Cl2 Eo = 1.3583 V

-----------------------------------------------------------------------------

2K + 2 Cl- ------------> 2 K+ + Cl2   

3)

Eo cell = Eo reduction - Eo oxidation

= 1.3583 - (- 2.95)

= 4.3083 V

overall E° =  4.3083 V

4)

As Eo increases, electrochemical reactions become more favoured