Find the bond enthalpy of S-S bond from the following data:\ $\mathrm{C}_{2} \mathrm{H}_{5}-\mathrm

Question

Find the bond enthalpy of S-S bond from the following data:\ $\mathrm{C}_{2} \mathrm{H}_{5}-\mathrm{S}-\mathrm{C}_{2} \mathrm{H}_{5(g)} ; \quad \Delta H_{f}^{\circ}=-147.23 \mathrm{~kJ} \mathrm{~mol}^{-1}$\ $\mathrm{C}_{2} \mathrm{H}_{5}-\mathrm{S}-\mathrm{S}-\mathrm{C}_{2} \mathrm{H}_{5(g)} ; \Delta H_{f}^{\circ}=-201.92 \mathrm{~kJ} \mathrm{~mol}^{-1}$\ $\mathrm{S}_{(g)}, \Delta H_{	ext {vap }(s)}^{\circ}=222.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$\

Professor PC Thomas Classes · Answer

(b) : $B E_{(\mathrm{S}-\mathrm{S})}=\Delta H_{	ext {vap }}(\mathrm{S})-\Delta H_f^{\circ}$
$
\begin{aligned}
& =\Delta H_{	ext {vap }}(\mathrm{S})-\left\{\Delta H_f^{\circ}\left(\mathrm{C}_2 \mathrm{H}_5 \mathrm{~S}-\mathrm{SC}_2 \mathrm{H}_5ight)ight\}-\Delta H_f^{\circ}\left(\mathrm{C}_2 \mathrm{H}_5-\mathrm{S}-\mathrm{C}_2 \mathrm{H}_5ight) \
& =222.80-\{-201.92-(-147.23)\}=277.49 \mathrm{~kJ} \mathrm{~mol}^{-1}
\end{aligned}
$