Problem 1
Classify each of the following as spontaneous or nonspontaneous processes: a) the browning of a cut apple slice on a snack tray over time b) the rolling of a ball uphill c) the formation of diamond from the graphite in your pencil d) the melting of ice cubes in a glass of water you are holding
Problem 2
State the second law of thermodynamics.
Problem 3
What sign would you expect for \(\Delta S\) for the following processes? a) water freezing in a lake during a cold Alberta winter b) \(\mathrm{AB}(\mathrm{s})+\mathrm{CD}(\mathrm{s}) \rightarrow \mathrm{AC}(\mathrm{g})+\mathrm{BD}(\mathrm{g})\) c) a balloon with a fixed amount of gas stretched to a larger volume d) the sublimation of dry ice e) \(3 \mathrm{E}_{2} \mathrm{~F}_{2}(\mathrm{~g}) \rightarrow \mathrm{E}_{6} \mathrm{~F}_{6}(\mathrm{~g})\)
Problem 4
Which of the following would you expect to have the higher standard molar entropy, \(S^{0} ?\) a) \(\mathrm{Br}_{2}(\ell)\) or \(\mathrm{Br}_{2}(\mathrm{~g})\) b) \(\mathrm{NO}_{2}(\mathrm{~g})\) or \(\mathrm{NO}(\mathrm{g})\) c) \(\mathrm{C}_{2} \mathrm{H}_{6}(\mathrm{~g})\) or \(\mathrm{C}_{5} \mathrm{H}_{12}(\mathrm{~g})\)
Problem 7
A chemical reaction has \(\Delta H^{0}=-43.5 \mathrm{~kJ}\) and \(\Delta S^{0}=-65.8 \mathrm{~J} / \mathrm{K} .\) Calculate \(\Delta G^{0}\) at \(298 \mathrm{~K}\). Is this a spontaneous process?
Problem 9
Find the standard Gibbs energy change for the reaction \(\mathrm{CaCO}_{3}(\mathrm{~s}) \rightarrow \mathrm{CaO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{~g})\) The \(\Delta G_{f}{ }^{\circ}\) values for the three components of this reaction system are \(\mathrm{CaCO}_{3}(\mathrm{~s}):-1128 \mathrm{~kJ} \mathrm{~mol}^{-1} ; \mathrm{CaO}(\mathrm{s})\) : \(-603.5 \mathrm{~kJ} / \mathrm{mol} ; \mathrm{CO}_{2}(\mathrm{~g}):-137.2 \mathrm{~kJ} / \mathrm{mol} .\)
Problem 11
Determine if the following reactions would be spontaneous at any temperature, nonspontaneous at any temperature, spontaneous at low temperature but not high temperature, or spontaneous at high temperature but not low temperature: a) \(\Delta H^{0}=-750 \mathrm{~kJ}\) and \(\Delta S^{0}=250 \mathrm{~J} / \mathrm{K}\) b) \(\Delta H^{0}=-100 \mathrm{~kJ}\) and \(\Delta S^{0}=-300 \mathrm{~J} / \mathrm{K}\) c) \(\Delta H^{0}=95 \mathrm{~kJ}\) and \(\Delta S^{0}=-70 \mathrm{~J} / \mathrm{K}\) d) \(\Delta H^{0}=400 \mathrm{~kJ}\) and \(\Delta S^{0}=500 \mathrm{~J} / \mathrm{K}\)
Problem 12
The \(K_{\mathrm{a}}\) for acetic acid, \(\mathrm{CH}_{3} \mathrm{COOH}\), is \(1.75 \times 10^{-5}\) at \(25^{\circ} \mathrm{C}\). a) Using the \(K_{\mathrm{a}}\) value, determine the \(\Delta G^{0}\) for the dissociation of acetic acid in aqueous solution. b) What is the value of \(\Delta G\) when \(\left[\mathrm{H}^{+}\right]\) is \(7.5 \times 10^{-2} \mathrm{M},\left[\mathrm{CH}_{3} \mathrm{COO}\right]\) is \(2.5 \times 10^{-2} \mathrm{M}\), and \(\left[\mathrm{CH}_{3} \mathrm{COOH}\right]\) is \(0.10 \mathrm{M} ?\)
