Question

Standard electrode potential for Sn$^{4+}$/Sn$^{2+}$ couple is +0.15 V and that for the Cr$^{3+}$/Cr couple is -0.74 V. The two couples in their standard states are connected to make a cell. The cell potential will be:

• A. +1.19 V
• B. +0.89 V
• C. +0.18 V
• D. +1.83 V

Hint:

The cell potential is calculated by subtracting the anode potential from the cathode potential.

Answer 1

The Correct Option is B

To resolve the issue, we must determine the cell potential of the electrochemical cell formed by the standard state Sn$^{4+}$/Sn$^{2+}$ and Cr$^{3+}$/Cr couples.

1. Standard Electrode Potentials:
The given standard electrode potentials (E°) are:

• Sn$^{4+}$/Sn$^{2+}$: E° = +0.15 V
• Cr$^{3+}$/Cr: E° = -0.74 V

The cell potential (E°cell) is the difference between the electrode potentials of the two half-reactions. The couple with the more positive potential will be reduced, and the other will be oxidized.

2. Anode and Cathode Identification:
Based on the potentials: - Sn$^{4+}$ will be reduced to Sn$^{2+}$ (cathode) due to its more positive potential (+0.15 V). - Cr will be oxidized to Cr$^{3+}$ (anode) due to its more negative potential (-0.74 V).

3. Cell Potential Calculation:
The cell potential (E°cell) is calculated using: E°cell = E°(cathode) - E°(anode)
Substituting values: E°cell = (+0.15 V) - (-0.74 V)
E°cell = 0.15 V + 0.74 V = 0.89 V

Conclusion:
The calculated cell potential is 0.89 V.