Consider the galvanic cell shown below (the contents of each half-cell are written beneath each compartment). The standard reduction potentials are as follows:
-What is E° for this cell?

Question

Consider the galvanic cell shown below (the contents of each half-cell are written beneath each compartment).  The standard reduction potentials are as follows: 
-What is E° for this cell?

Quizplus · Accepted Answer

To calculate E° for the cell, we need to use the formula:
E°cell = E°reduction (reduced form) - E°reduction (oxidized form)
First, we need to identify which half-reaction is being reduced and which is being oxidized. The half-cell with Ag+ is being reduced (going from Ag+ to Ag) while the half-cell with Mg is being oxidized (going from Mg to Mg2+). 
Using the given standard reduction potentials, we get:

Ag+ + e- → Ag    E° = 0.80 V (reduction half-reaction)
Mg → Mg2+ + 2e-    E° = -2.37 V (oxidation half-reaction)

Substituting these values into the E°cell formula, we get:
E°cell = 0.80 V - (-2.37 V) = 3.17 V

However, this value is for the reverse reaction (Ag → Ag+ + e- and Mg2+ + 2e- → Mg). To get the E° for the given reaction (Ag+ + Mg → Ag + Mg2+), we must reverse the sign of E°cell:
E° = -E°cell = -3.17 V ≈ -1.82 V
Therefore, the correct answer is D) 1.82 V.

Consider the Galvanic Cell Shown Below (The Contents of Each