Answer
$30.8\,kJ/mol$
Work Step by Step
Recall that $\Delta S_{vap}=\frac{\Delta H_{vap}}{T_{b}}$.
$\implies \Delta H_{vap}=\Delta S_{vap}\times T_{b}$
Given that $T_{b}=80.1^{\circ}C=(80.1+273.15)K=353.25\,K$
For benzene, $\Delta S_{vap}=87.2\,J\,K^{-1}mol^{-1}$
Then, $\Delta H_{vap}=(87.2\,J\,K^{-1}mol^{-1})(353.25\,K)$
$=30800\,J\,mol^{-1}=30.8\,kJ/mol$
