A heat engine absorbs heat ${\mathrm{Q}}_1$ at temperature ${\mathrm{T}}_1$ and heat ${\mathrm{Q}}_2$ at temperature ${\mathrm{T}}_2$. Work done by the engine is $\left({\mathrm{Q}}_1+{\mathrm{Q}}_2\right) \mathrm{J}$. This data

The efficiency of an hypothetical cell is about $84\%$ which involves the following reaction:

$\mathrm{A}\left(\mathrm{s}\right)+{\mathrm{B}}^{2+}\left(\mathrm{aq}\right)⟶{\mathrm{A}}^{2+}\left(\mathrm{aq}\right)+\mathrm{B}\left(\mathrm{s}\right); \mathrm{\Delta H}=-285 \mathrm{kJ}$

Then, the standard electrode potential of the cell will be (Assume as $\mathrm{\Delta S}=0$)

For the reaction,

${\mathrm{H}}_2 \left(\mathrm{g}\right)+\frac{1}{2}{\mathrm{O}}_2 \left(\mathrm{g}\right)\to {\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right), \mathrm{\Delta H}=-285.8 \mathrm{kJ} {\mathrm{mol}}^{-1}$

$\mathrm{\Delta S}=-0.163 \mathrm{kJ} {\mathrm{mol}}^{-1} {\mathrm{K}}^{-1}$.

What is the value of free energy change, at $27 °\mathrm{C}$ for the reaction?