\(\mathrm{C}_{\mathrm{(s)}}+\mathrm{O}_{2(\mathrm{g})} \longrightarrow \mathrm{CO}_{2(\mathrm{g})} \quad \Delta_{f} H=-393.5 \;\mathrm{kJ}\, \mathrm{mol}^{-1}\)
\((1 \text { mole }=44 \,g)\)
Heat released on formation of \(44 \;\mathrm{g}\; \mathrm{CO}_{2}=-393.5\; \mathrm{kJ} \,\mathrm{mol}^{-1}\)
Heat released on formation of \(35.2\; \mathrm{g} \;\mathrm{CO}_{2}\)
\(=\frac{-393.5\, \mathrm{kJ}\, \mathrm{mol}^{-1}}{44 \,\mathrm{g}} \times 35.2 \;\mathrm{g}\)
\(=-314.8 \;\mathrm{kJ}\, \mathrm{mol}^{-1}\)