Standard enthalpy of vapourisation for $\mathrm{CCl}_4$ is $30.5 \mathrm{~kJ} \mathrm{~mol}^{-1}$. Heat required for vapourisation of $284 \mathrm{~g}$ of $\mathrm{CCl}_4$ at constant temperature is ________ $\mathrm{kJ}$.

(Given molar mass in $\mathrm{g} \mathrm{mol}^{-1} ; \mathrm{C}=12, \mathrm{Cl}=35.5$)