# Question 20.10: Calculating the Cell emf from Free-Energy Change Suppose the...

Calculating the Cell emf from Free-Energy Change

Suppose the reaction of zinc metal and chlorine gas is utilized in a voltaic cell in which zinc ions and chloride ions are formed in aqueous solution.

$\mathrm{Zn}(s)+\mathrm{Cl}_{2}(g) \stackrel{\mathrm{H}_{2} \mathrm{O}}{\longrightarrow} \mathrm{Zn}^{2+}(a q)+2 \mathrm{Cl}^{-}(a q)$

Calculate the standard emf for this cell at $25^{\circ} \mathrm{C}$ from standard free energies of formation (see Appendix C).

PROBLEM STRATEGY

Calculate $\Delta G^{\circ}$ and substitute it and the value of $n$ into the equation $\Delta G^{\circ}=$ $-n F E_{\text {cell. }}^{\circ}$ Solve for $E_{\text {cell. }}^{\circ}$

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