Problem 2
(a) Calculate the work done on the surroundings at 1 bar pressure and \(298 \mathrm{K}\) when 0.200 mole \(\mathrm{H}_{2} \mathrm{O}_{2}\) decomposes (volume occupied by 1 mole of gas at 1 bar and \(273 \mathrm{K}=22.7 \mathrm{dm}^{3}\) ). (b) If the standard enthalpy of reaction is \(-98.2 \mathrm{kJ}\) per mole of \(\mathrm{H}_{2} \mathrm{O}_{2}\) what is the corresponding change in the internal energy of the system?
Problem 4
How does the molar heat capacity of a substance differ from the specific heat capacity?
Problem 8
(a) Determine \(\Delta_{\mathrm{r}} H^{\circ}\) for the reaction: \(\mathrm{CO}(\mathrm{g})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{g}) \rightarrow \mathrm{CO}_{2}(\mathrm{g})\) given that, at \(298 \mathrm{K}\) \(\Delta_{\mathrm{f}} H^{\circ}(\mathrm{CO}, \mathrm{g})=-110.5 \mathrm{kJ} \mathrm{mol}^{-1}\) and \(\Delta_{\mathrm{f}} H^{\mathrm{o}}\left(\mathrm{CO}_{2}, \mathrm{g}\right)=-393.5 \mathrm{kJ} \mathrm{mol}^{-1}\) (b) Calculate \(\Delta_{\mathrm{r}} H^{\circ}(320 \mathrm{K})\) for the above reaction given that \(C_{P}(298-320 \mathrm{K})\) for \(\mathrm{CO}(\mathrm{g}), \mathrm{O}_{2}(\mathrm{g})\) and \(\mathrm{CO}_{2}(\mathrm{g})=29.2,29.4\) and \(37.2 \mathrm{JK}^{-1} \mathrm{mol}^{-1}\) respectively.
Problem 9
Determine the Gibbs energy change at \(298 \mathrm{K}\) that accompanies the reaction: \\[ \mathrm{B}_{2} \mathrm{H}_{6}(\mathrm{g})+6 \mathrm{H}_{2} \mathrm{O}(1) \rightarrow 2 \mathrm{B}(\mathrm{OH})_{3}(\mathrm{s})+6 \mathrm{H}_{2}(\mathrm{g}) \\] if values of \(\Delta_{\mathrm{f}} G^{\circ}(298 \mathrm{K})\) are \(\mathrm{B}_{2} \mathrm{H}_{6}(\mathrm{g})+87\) \\[ \mathrm{B}(\mathrm{OH})_{3}(\mathrm{s})-969, \mathrm{H}_{2} \mathrm{O}(\mathrm{l})-237 \mathrm{kJ} \mathrm{mol}^{-1} \\].
Problem 13
(a) At \(298 \mathrm{K}, \Delta_{\mathrm{f}} G^{\mathrm{o}}\left(\mathrm{OF}_{2}, \mathrm{g}\right)=+42 \mathrm{kJ} \mathrm{mol}^{-1}\) From this value, can you say whether \(\mathrm{OF}_{2}\) will form when \(F_{2}\) and \(O_{2}\) combine at 298 K? (b) For the reaction: $$\mathrm{H}_{2} \mathrm{O}_{2}(1) \rightarrow \mathrm{H}_{2} \mathrm{O}(1)+\frac{1}{2} \mathrm{O}_{2}(\mathrm{g})$$ \\[ \Delta_{\mathrm{r}} G^{\mathrm{o}}(298 \mathrm{K})=-117 \mathrm{kJ} \mathrm{mol}^{-1} . \text {Suggest why } \mathrm{H}_{2} \mathrm{O}_{2} \\] does not decompose spontaneously on standing. Under what circumstances might \(\mathrm{H}_{2} \mathrm{O}_{2}\) rapidly decompose at \(298 \mathrm{K} ?\)
Problem 18
(a) Determine \(K\) for the formation of \(\mathrm{NO}\) from \(\mathrm{O}_{2}\) and \(\mathrm{N}_{2}\) at \(298 \mathrm{K}\) if \(\Delta_{\mathrm{f}} G^{\mathrm{o}}(\mathrm{NO}, \mathrm{g}, 298 \mathrm{K})=+87 \mathrm{kJ}\) \(\mathrm{mol}^{-1} \cdot(\mathrm{b}) \mathrm{What}\) does the answer to part (a) tell you about the position of the equilibrium: \(\frac{1}{2} \mathrm{N}_{2}(\mathrm{g})+\frac{1}{2} \mathrm{O}_{2}(\mathrm{g}) \rightleftharpoons \mathrm{NO}(\mathrm{g}) ?\)
Problem 19
The value of \(K\) for the equilibrium: $$\frac{1}{2} \mathrm{H}_{2}(\mathrm{g})+\frac{1}{2} \mathrm{I}_{2}(\mathrm{g}) \rightleftharpoons \mathrm{HI}(\mathrm{g})$$ is 0.5 at \(298 \mathrm{K}\) and 6.4 at \(800 \mathrm{K} .\) Calculate \(\Delta_{\mathrm{r}} G^{\circ}\) at each temperature and comment on how raising the temperature from 298 to \(800 \mathrm{K}\) affects the formation of HI from its constituent elements.
Problem 22
Predict, with reasoning, whether \(\Delta S^{\circ}\) will be positive, negative or zero for each of the following: (a) \(\mathrm{Na}(\mathrm{s}) \rightarrow \mathrm{Na}(\mathrm{g})\) (b) \(2 \mathrm{Cl}(\mathrm{g})-\mathrm{Cl}_{2}(\mathrm{g})\) (c) \(2 \mathrm{CO}(\mathrm{g})+\mathrm{O}_{2}(\mathrm{g}) \rightarrow 2 \mathrm{CO}_{2}(\mathrm{g})\)
Problem 24
The molar entropy, \(S^{\circ},\) of \(\mathrm{HCl}\) at \(298 \mathrm{K}\) is \(186.9 \mathrm{JK}^{-1} \mathrm{mol}^{-1} .\) Find \(S^{\circ}(350 \mathrm{K})\) if \(C_{P}(298-350 \mathrm{K})\) is \(29.1 \mathrm{JK}^{-1} \mathrm{mol}^{-1}\).
Problem 25
Values of \(S^{\circ}(\mathrm{Cu}, \mathrm{s})\) at \(400 \mathrm{K}\) and \(500 \mathrm{K}\) are 40.5 and \(46.2 \mathrm{JK}^{-1} \mathrm{mol}^{-1}\) respectively. Estimate the molar heat capacity of copper over this temperature range.
