If the concentrations of `Fe^(2+)` and `Fe^(3+)` are equal, what should be the concentration of `Ag^+` ions to have zero voltage for a galvanic cell made up of `Ag^(+)|Ag` and `Fe^(3+)| Fe^(2+)` electrodes. Also, calculate the equilibrium constant at `25^@C` for the following cell reaction:` Fe^(2+) + Ag^+ = Fe^(3+) + Ag`.

Explanation

To solve the problem, we need to find the concentration of \( \text{Ag}^+ \) ions that will result in zero voltage for the galvanic cell composed of \( \text{Ag}^+|\text{Ag} \) and \( \text{Fe}^{3+}|\text{Fe}^{2+} \) electrodes. We also need to calculate the equilibrium constant for the reaction \( \text{Fe}^{2+} + \text{Ag}^+ \rightleftharpoons \text{Fe}^{3+} + \text{Ag} \).

### Step 1: Identify Standard Reduction Potentials
The standard reduction potentials for the half-reactions are:
- For \( \text{Ag}^+ + e^- \rightarrow \text{Ag} \): \( E^\circ = +0.799 \, \text{V} \)
- For \( \text{Fe}^{3+} + e^- \rightarrow \text{Fe}^{2+} \): \( E^\circ = +0.771 \, \text{V} \)

### Step 2: Calculate the Standard Cell Potential
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