Standard free energies of formation (in $\mathrm{kJ} / \mathrm{mol}$ ) at $298 \mathrm{~K}$ are $-237.2,-394…

Standard free energies of formation (in $\mathrm{kJ} / \mathrm{mol}$ ) at $298 \mathrm{~K}$ are $-237.2,-394.4$ and -8.2 for $\mathrm{H}_2 \mathrm{O}(\mathrm{l}), \mathrm{CO}_2(\mathrm{~g})$ and pentane $(\mathrm{g})$ respectively. The value of $\mathrm{E}_{\text {cell }}^{\circ}$ for the pentaneoxygen fuel cell is
  1. $0.0968 \mathrm{~V}$
  2. $1.968 \mathrm{~V}$
  3. $2.0968 \mathrm{~V}$
  4. $1.0968 \mathrm{~V}$

Solution

After calculation $\Delta \mathrm{G}^{\circ}$, use the formula, $\Delta \mathrm{G}^{\circ}=-n F E^{\circ}$ Here, $n=32$ is taken because balanced equation is $\mathrm{C}_5 \mathrm{H}_{12}+8 \mathrm{O}_2 \rightarrow 5 \mathrm{CO}_2+6 \mathrm{H}_2 \mathrm{O}$

Asked in: NEET 2008 (Mains)

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