How much heat will be liberated if \(10 \mathrm{~g}\) of hydrogen burns in excess oxygen according to the following thermochemical equation? \(\mathrm{H}_{2(\mathrm{~g})}+21 \mathrm{O}_{2(\mathrm{~g})} \rightarrow \mathrm{H}_2 \mathrm{O}_{(0)} \Delta=-286 \mathrm{~kJ}\)
A. \(-1430 \mathrm{~kJ}\) B. \(-2860 \mathrm{~kJ}\) C. \(-572 \mathrm{~kJ}\) D. \(-286 \mathrm{~kJ}\)
Correct Answer: A
Explanation
\(\mathrm{n}_{\mathrm{H}_2}=\frac{10 \mathrm{~g}}{2 \mathrm{gmol}^{-1}}=5 \mathrm{~mol}\) Since the combustion of 1 mole of \(\mathrm{H}_2\) by a heat change of \(-286 \mathrm{~kJ}\). Heat released when 5 moles of hydrogen is burnt \(=\frac{-286 \mathrm{~kJ}}{1 \mathrm{~mol}} \times 5 \mathrm{~mol}\)
