Liquid bromine boils at 332. 7 E:. Estimate the enthalpy of formation of ${\mathrm{Br}}_2\left(g\right)\text{ in }\mathrm{kJ}\cdot {\mathrm{mol}}^{-1}$.

$S\mathrm{\%}/J\cdot {\mathrm{mol}}^{-1}\cdot {\mathbf{K}}^{-1}$
${\mathrm{Br}}_2\left(g\right)$	$58.6$
${\mathrm{Br}}_2\left(l\right)$	$36.4$

 

In the reaction we have,

$$\begin{gathered} {\mathrm{Br}}_2\left(l\right)⟶{\mathrm{Br}}_2\left(g\right);{\mathrm{\Delta S}}^{\circ }=58.6-36.4 \\ =22.2\mathrm{J}{\mathrm{mol}}^{-1}{\mathrm{K}}^{-1} \end{gathered}$$

$\mathrm{\Delta }{H}^{\circ }=\frac{332.7\times 22.2}{1000}=7.40\mathrm{kJ}/\mathrm{mol}$