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For the galvanic cell reaction Mg(s) + Zn2+(1 M) -> Zn(s) + Mg2+(1 M), the measured emf is 1.60 V. Determine the standard cell potential E°cell.

1. -1.60 V
2. 1.60 V
3. 0.0 V
4. 0.16 V

Correct answer: 1.60 V

Solution

By the Nernst equation, Ecell = E°cell - (0.0591/n)*log Q. Here Q = [Mg2+]/[Zn2+] = 1/1 = 1, so log Q = 0 and Ecell = E°cell. Thus E°cell equals the measured emf, 1.60 V.

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