The Enthalpy of combustion of $$\mathrm{C}_6 \mathrm{H}_5 \mathrm{COOH}(\mathrm{s})$$ at $$25^{\circ} \mathrm{c}$$ and 1.0 atm pressure is $$-2546 \mathrm{~kJ} / \mathrm{mol}$$. What is the Internal energy change for this reaction?

Given :

$$ \begin{gathered} \Delta \mathrm{H}^0 \mathrm{f}_{\text {of }} \mathrm{CO}_2(\mathrm{~g})=-393.5 \mathrm{~kJ} / \mathrm{mol} \\ \Delta \mathrm{H}^0{ }_{\mathrm{f}} \text { of } \mathrm{H}_2 \mathrm{O}(\mathrm{l})=-286 \mathrm{~kJ} / \mathrm{mol} \\ \Delta \mathrm{H}^0{ }_{\mathrm{f}} \text { of } \mathrm{C}_3 \mathrm{H}_6(\mathrm{~g})=+20.6 \mathrm{~kJ} / \mathrm{mol} \end{gathered} $$

$$\Delta \mathrm{H}^0$$ isomerisation of Cyclopropane to Propene $$=-33 \mathrm{~kJ} / \mathrm{mol}$$

What is the standard enthalpy of combustion of Cyclopropane?

5.0 moles of an Ideal gas at 3.0 atm pressure and $$27^{\circ} \mathrm{C}$$ is compressed isothermally to half its volume by application of an external pressure of $$3.5 \mathrm{~atm}$$. What is the amount of work done (in joules) on the gas? Given: $$1 \mathrm{~L} \mathrm{~atm}=101.3 \mathrm{~J}: \mathrm{R}=0.082 \mathrm{~L} \mathrm{~atm} \mathrm{~K}{ }^{-1} \mathrm{~mol}^{-1}$$

The $$\Delta \mathrm{H}_{(\mathrm{f})}^{\mathrm{o}}$$ of $$\mathrm{NO}_2(\mathrm{~g})$$ and $$\mathrm{N}_2 \mathrm{O}_4(\mathrm{~g})$$ are 16.0 and $$4.0 \mathrm{k} \mathrm{cal} \mathrm{mol}^{-1}$$ respectively. The heat of dimerisation of $$\mathrm{NO}_2$$ in $$\mathrm{k}$$ cal is :