In a constant volume calorimeter, `3.5 g` of a gas with molecular weight `28` was burnt in excess oxygen at `298.0 K`. The temperature of the calorimeter was found to increase from `298.0 K to 298.45 K` due to the combustion process. Given that the heat capacity of the calorimeter is `2.5 kJ K^(-1)`, find the numerical value for the enthalpy of combustion of the gas in `kJ mol^(-1)`

Explanation

Heat of combustion of 3.5 g of the gas = Heat taken by the calorimeter = 2.5 (298.45 – 298.0) kJ
`9kJ "mol"^(-1)`