4. Use the Nernst equation to calculate the cell voltage (E) for the following r

Question

4. Use the Nernst equation to calculate the cell voltage (E) for the following redox reaction: a. Fe3+ (aq) + Cu (s) Cu2+ (aq) + Fe2+ (aq) 3+ 0.05 andCu2+ 0.125M at 25°C, and . I, given that Ie 1, Fe3+ + e Fe2+ 2 . Cu Eo = 0.77 V E 0.34 V 2+2e Cu 5. Use the information provided in Question 4 to calculate the change in free energy (AG) and char in entropy (AS) for the redox reaction: a. Fe3+ (aq) + Cu (s) Cu2+ (aq) + Fe2+ (aq) i, what do the G and S values indicate about the spontaneity of the redox reaction?

Explanation / Answer

4.

(a)

E0cell = E0Fe3+/Fe2+ - E0CU2+/Cu = 0.77 - 0.34 = 0.43 V

Balanced equation is,

2 Fe3+ + Cu (s) ----------> Cu2+ + Fe2+

Using Nernst equation,

Ecell = E0cell - (0.0591/n)Log[Cu2+][Fe2+]2/[Fe3+]2

Ecell = 0.43 - (0.0591 / 2)*Log[(0.125)(1.00)2 / (0.05)2]

Ecell = 0.38 V

5.

deltaG = - n F Ecell = - 2 * 96500 * 0.38 = - 73300 J = - 73.3 kJ

Since deltaG = -ve, the reaction is spontaneous.

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