For the reaction, \(2 \mathrm{H}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})} \longrightarrow 2 \mathrm{H}_2 \mathrm{O}_{(\mathrm{g})}, \Delta \mathrm{H}^{\circ}=-573.2 \mathrm{~kJ}\) What is heat of decomposition of water per mol?

The given reaction is:
\(2 \mathrm{H}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})} \longrightarrow 2 \mathrm{H}_2 \mathrm{O}_{(l)} ; \Delta_{\mathrm{f}} \mathrm{H}^{\circ}=-573.2\)\(\mathrm{~kJ} \mathrm{~mol}^{-1}\)
Reversing the above reaction,
\(2 \mathrm{H}_2 \mathrm{O}_{(l)} \longrightarrow 2 \mathrm{H}_{2(\mathrm{~g})}+\mathrm{O}_{2(\mathrm{~g})} \Delta_{\mathrm{d}} \mathrm{H}^{\circ}=573.2\)\(\mathrm{~kJ} \mathrm{~mol}^{-1}\)
\(\therefore\) For decomposition of 1 mole of water,
\(\mathrm{H}_2 \mathrm{O}_{(l)} \longrightarrow \mathrm{H}_{2(\mathrm{~g})}+\frac{1}{2} \mathrm{O}_{2(\mathrm{~g})} ; \Delta_{\mathrm{d}} \mathrm{H}^{\mathrm{o}}=286.6\)\(\mathrm{~kJ} \mathrm{~mol}^{-1}\)