If 100 mole of $H_2{O}_2$ decomposes at 1 bar and 300K, the work done (kJ) by one mole of  $O_2\left(g\right)$ as it expands against 1 bar pressure is:

$2{\mathrm{H}}_2{\mathrm{O}}_2\left(\mathcal{l}\right)\rightleftharpoons 2{\mathrm{H}}_2\mathrm{O}\left(\mathcal{l}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right) (\mathrm{R}=8.3{\mathrm{JK}}^{-1}{\mathrm{mol}}^{-1})$