Question

The standard reduction potential for \(Fe^{2+}/Fe\) and \(Sn^{2+}/Sn\) electrodes are -0.44 and -0.14 V respectively. For the cell reaction \(Fe^{2+} + Sn \rightarrow Fe + Sn^{2+}\), the standard emf is

• A. +0.30 V
• B. -0.58 V
• C. +0.58 V
• D. -0.30 V

Hint:

Always follow the given reaction direction. Do NOT flip signs unless reaction is reversed.

Answer 1

The Correct Option is D

Concept: \[ E^\circ_{cell} = E^\circ_{cathode} - E^\circ_{anode} \]

Step 1: Identify electrodes from given reaction.
\[ Fe^{2+} + 2e^- \rightarrow Fe \quad (\text{reduction, cathode}) \] \[ Sn \rightarrow Sn^{2+} + 2e^- \quad (\text{oxidation, anode}) \]

Step 2: Use standard reduction potentials.
\[ E^\circ_{Fe^{2+}/Fe} = -0.44\,V, \quad E^\circ_{Sn^{2+}/Sn} = -0.14\,V \]

Step 3: Calculate EMF.
\[ E^\circ_{cell} = (-0.44) - (-0.14) = -0.30\,V \] Conclusion:
Since EMF is negative, the given reaction is non-spontaneous.