# Question #1699a

Feb 27, 2017

$\triangle G \text{of change} = - 144750 J = - 144.75 k J$

#### Explanation:

Balance the reaction

$2 H {g}^{2 +} + S {n}^{4 +} - \to H g {2}^{2 +} + S {n}^{2 +}$

$S {n}^{4 +} + 2 {e}^{-} - - - - \to S {n}^{2 +}$ $\text{electrode potential at anode} = + 0.15 V$

$2 H {g}^{2 +} - - - - \to H g {2}^{+ 2} + 2 {e}^{-}$ $\text{electrode potential at cathode} = + 0.9 V$

EoCell= EoRed,Cathode - EoRed,Anode

Ecell = 0.9 - 0.15 = +0.75

$\triangle G \text{of change} = - v \cdot F \cdot {E}^{o}$

v is the electrons exchanged = 2e- but notice in the equation it is is written -v so take care of that
${E}^{o}$ we know already
$- 2 \cdot 96500 {\text{C/mol}}^{- 1} \cdot 0.75 V = - 144750 J$
$\triangle G \text{of change} = - 144750 J = - 144.75 k J$