Thermodynamics And Thermochemistry Result Question 25
25. The standard enthalpy of combustion at $25^{\circ} \mathrm{C}$ of hydrogen, cyclohexene $\left(\mathrm{C}6 \mathrm{H}{10}\right)$ and cyclohexane $\left(\mathrm{C}6 \mathrm{H}{12}\right)$ are $-241 , -3800$ and $-3920 \mathrm{~kJ} / \mathrm{mol}$ respectively. Calculate the heat of hydrogenation of cyclohexene.
(1989,2 M)
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Answer:
Correct Answer: 25. $(-121 \mathrm{~kJ} / \mathrm{mol})$
Solution:
$\Delta H=\Sigma \Delta H_{\text {comb }}^{\circ} \text { (reactants) }-\Sigma \Delta H_{\text {comb }}^{\circ} \text { (products) }$
$ =-3800-241-(-3920) $
$ =-121 \mathrm{~kJ} / \mathrm{mol}$
BETA
