Consider the reaction $\mathrm{NH}_4 \mathrm{NO}_3(\mathrm{~s}) \longrightarrow \mathrm{N}_2 \mathrm{O}(\mathrm{g})+$ $2 \mathrm{H}_2 \mathrm{O}(1)$ at $298 \mathrm{~K}$.
(c) What is the value of $K$ at $298 \mathrm{~K}$ ?

Pentane is one of the most volatile of the hydrocarbons in gasoline. At $298.15 \mathrm{~K}$, the following enthalpies of formation are given for pentane: $\Delta_f H^{\circ}\left[\mathrm{C}_5 \mathrm{H}_{12}(1)\right]=$ $-173.5 \mathrm{~kJ} \mathrm{~mol}^{-1} ; \Delta_f H^{\circ}\left[\mathrm{C}_5 \mathrm{H}_{12}(\mathrm{~g})\right]=-146.9 \mathrm{~kJ} \mathrm{~mol}^{-1}$.
(b) Estimate $\Delta_{\mathrm{vap}} G^{\circ}$ for pentane at $298 \mathrm{~K}$.

Consider the reaction $\mathrm{NH}_4 \mathrm{NO}_3(\mathrm{~s}) \longrightarrow \mathrm{N}_2 \mathrm{O}(\mathrm{g})+$ $2 \mathrm{H}_2 \mathrm{O}(1)$ at $298 \mathrm{~K}$.
(a) Is the forward reaction endothermic or exothermic?

Pentane is one of the most volatile of the hydrocarbons in gasoline. At $298.15 \mathrm{~K}$, the following enthalpies of formation are given for pentane: $\Delta_f H^{\circ}\left[\mathrm{C}_5 \mathrm{H}_{12}(1)\right]=$ $-173.5 \mathrm{~kJ} \mathrm{~mol}^{-1} ; \Delta_f H^{\circ}\left[\mathrm{C}_5 \mathrm{H}_{12}(\mathrm{~g})\right]=-146.9 \mathrm{~kJ} \mathrm{~mol}^{-1}$.
(a) Estimate the normal boiling point of pentane.

A handbook lists the following standard enthalpies of formation at $298 \mathrm{~K}$ for cyclopentane, $\mathrm{C}_5 \mathrm{H}_{10}: \quad \Delta_{\mathrm{f}} H^{\circ}\left[\mathrm{C}_5 \mathrm{H}_{10}(1)\right]=-105.9 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $\Delta_f H^{\circ}\left[C_5 \mathrm{H}_{10}(\mathrm{~g})\right]=-77.2 \mathrm{~kJ} \mathrm{~mol}^{-1}$.
(c) Comment on the significance of the sign of $\Delta_r G^{\circ}$ at $298 \mathrm{~K}$.

A handbook lists the following standard enthalpies of formation at $298 \mathrm{~K}$ for cyclopentane, $\mathrm{C}_5 \mathrm{H}_{10}: \quad \Delta_{\mathrm{f}} H^{\circ}\left[\mathrm{C}_5 \mathrm{H}_{10}(1)\right]=-105.9 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $\Delta_f H^{\circ}\left[C_5 \mathrm{H}_{10}(\mathrm{~g})\right]=-77.2 \mathrm{~kJ} \mathrm{~mol}^{-1}$.
(b) Estimate $\Delta_{\mathrm{r}} G^{\circ}$ for the vaporization of cyclopentane at $298 \mathrm{~K}$.

A handbook lists the following standard enthalpies of formation at $298 \mathrm{~K}$ for cyclopentane, $\mathrm{C}_5 \mathrm{H}_{10}: \quad \Delta_{\mathrm{f}} H^{\circ}\left[\mathrm{C}_5 \mathrm{H}_{10}(1)\right]=-105.9 \mathrm{~kJ} \mathrm{~mol}^{-1}$ and $\Delta_f H^{\circ}\left[C_5 \mathrm{H}_{10}(\mathrm{~g})\right]=-77.2 \mathrm{~kJ} \mathrm{~mol}^{-1}$.
(a) Estimate the normal boiling point of cyclopentane.

Explain briefly why
(b) $\Delta_{\mathrm{r}} G^{\circ}$ is so important in dealing with the question of spontaneous change, even though the conditions employed in a reaction are very often nonstandard.

Explain briefly why
(a) the change in entropy in a system is not always a suitable criterion for spontaneous change;

Two correct statements about the reversible reaction $\mathrm{N}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g})$ are
(e) the composition of an equilibrium mixture of the gases is independent of the temperature.

Without performing detailed calculations, indicate whether any of the following reactions would occur to a measurable extent at $298 \mathrm{~K}$.
(c) Formation of $\mathrm{BrCl}$ :

$$\mathrm{Br}_2(\mathrm{l})+\mathrm{Cl}_2(\mathrm{~g}) \longrightarrow 2 \mathrm{BrCl}(\mathrm{g})$$

Two correct statements about the reversible reaction $\mathrm{N}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g})$ are
(d) $K=K_c;$

Without performing detailed calculations, indicate whether any of the following reactions would occur to a measurable extent at $298 \mathrm{~K}$.
(b) Dissociation of $\mathrm{N}_2 \mathrm{O}_4$ to $\mathrm{NO}_2$ :

$$\mathrm{N}_2 \mathrm{O}_4(\mathrm{~g}) \longrightarrow 2 \mathrm{NO}_2(\mathrm{~g})$$

Two correct statements about the reversible reaction $\mathrm{N}_2(\mathrm{~g})+\mathrm{O}_2(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g})$ are
(c) the equilibrium amount of $\mathrm{NO}$ increases if an equilibrium mixture is transferred from a $10.0 \mathrm{~L}$ container to a $20.0 \mathrm{~L}$ container;