Question

For hydrogen-oxygen fuel cell, the cell reaction is \[ 2\text{H}_2(g) + \text{O}_2(g) \rightarrow 2\text{H}_2\text{O}(l) \] If \( \Delta G^\circ (H_2O) = -237.2 \, \text{kJ mol}^{-1} \), then emf of this cell is

• A. +246 V
• B. -246 V
• C. +1.23 V
• D. -1.23 V

Hint:

The emf of a cell is related to the Gibbs free energy by the equation \( \Delta G = -nFE \).

Answer 1

The Correct Option is C

Step 1: Gibbs Free Energy and Cell Potential.
The relationship between Gibbs free energy change and cell potential is given by: \[ \Delta G = -nFE \] Substituting the values \( \Delta G^\circ = -237.2 \, \text{kJ/mol} \) and \( n = 2 \), we get the emf \( E = 1.23 \, \text{V} \).
Step 2: Conclusion.
The correct answer is (C), +1.23 V.