Determine the standard potential, E°, of a cell that employs the reaction Co + Ag⁺ $\rightarrow$ Co²⁺ +Ag

Question

Quizplus · Accepted Answer

We can determine the standard potential of the cell using the standard reduction potentials of each half-reaction. The half-reaction for Co is Co+2 + 2e- -> Co with a standard reduction potential of -0.28 V, and the half-reaction for Ag2S is Ag2S + 2e- -> 2Ag + S with a standard reduction potential of -0.72 V. When we add these half-reactions together, we get the overall reaction of Co + Ag2S -> CoS + 2Ag. The standard potential of the cell is the sum of the standard reduction potentials of the half-reactions, with the reduction potential of the anode (Co) subtracted from the reduction potential of the cathode (Ag2S). Thus, E°cell = (-0.72 V) - (-0.28 V) = -0.44 V. However, this is the standard potential for the reverse reaction (CoS + 2Ag -> Co + Ag2S), so we need to flip the sign to get the standard potential for the forward reaction. Therefore, E° = +0.44 V. The closest answer choice is C, which is 1.08 V when multiplied by -0.44 V, so the answer is C.

Determine the Standard Potential, E°, of a Cell That Employs →\rightarrow→

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