In an electrochemical cell, the potential difference between two electrodes unde

Question

In an electrochemical cell, the potential difference between two electrodes under standard conditions is known as the standard cell potential (Ecell). The standard cell potential can be used to identify the overall tendency of a redox reaction to occur spontaneously. The spontaneity of a reaction is identified using the Gibbs free energy G. G is related to Ecell. Ecell and G are also related to equilibrium constant Keq of the reaction.

Part A

In the activity, click on the Ecell and Keq quantities to observe how they are related. Use this relation to calculate Keq for the following redox reaction that occurs in an electrochemical cell having two electrodes: a cathode and an anode. The two half-reactions that occur in the cell are

Cu2+(aq)+2eCu(s) and Fe(s)Fe2+(aq)+2e

The net reaction is

Cu2+(aq)+Fe(s)Cu(s)+Fe2+(aq)

Use the given standard reduction potentials in your calculation as appropriate.

Express your answer numerically to three significant figures.

Keq=???

Explanation / Answer

E0Cu2+/Cu = 0.337 V

E0Fe2+/Fe = - 0.440 V

E0cell = E0Cu2+/Cu - E0Fe2+/Fe = 0.337 - (0.440) = 0.777 V

G0 = - n F E0cell and G0 = - R T lnK

So, R T lnK = n F E0cell

K = e(n F E0cell/RT) = e(2*96500*0.777/8.314*298.15) = 1.88 * 1026

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