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)`

Answer

` to 9`

Explanation

Enthalpy of combustion of `3.5 g` of the gas `=(2.5 kJ K^(-1))(0.45K)=1.125kJ`
`:. "molar mass of the gas" = 28`, enthalpy of
combustion/mole `=(1.125)/(3.5)xx28=9 kJ`