The structure of ethylene is \(\mathrm{H}_{2} \mathrm{C}=\mathrm{CH}_{2}\). Estimate the enthalpy of reaction when \(1 \mathrm{kmol}\) of ethylene is completely oxidised. Compare the value obtained with the tabulated value of \(-1323.2 \mathrm{MJ} / \mathrm{kmol}\). Give reasons for the difference between the values.

Neglecting dissociation, find the temperature reached after constant pressure combustion of ethylene with \(50 \%\) excess air if the initial temperature of the reactants is \(400 \mathrm{~K}\). The specific heat at constant pressure of ethylene is approximately \(1.71 \mathrm{~kJ} / \mathrm{kg} \mathrm{K}\) over the temperature range of the reactants.

[1302.3 MJ/kmol; \(2028 \mathrm{~K}]\)