Problem 23
Which one of the following has \(\Delta \mathrm{S}^{\circ}\) greater than zero? (a) \(\mathrm{CaO}(\mathrm{s})+\mathrm{CO}_{2}(\mathrm{~g}) \rightleftharpoons \mathrm{CaCO}_{3}(\mathrm{~g})\) (b) \(\mathrm{NaCl}(\mathrm{aq}) \rightleftharpoons \mathrm{NaCl}(\mathrm{s})\) (c) \(\mathrm{NaNO}_{3}(\mathrm{~s}) \rightleftharpoons \mathrm{Na}^{+}(\mathrm{aq})+\mathrm{NO}_{3}^{-}(\mathrm{aq})\) (d) \(\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \rightleftharpoons-2 \mathrm{NH}_{3}(\mathrm{~g})\)
Problem 25
For a spontaneous process, the correct statement is (a) entropy of the system always increases (b) free energy of the system always increases (c) total entropy change is always negative (d) total entropy change is always positive
Problem 27
Which of the following is not an endothermic reaction? (a) combustion of methane (b) decomposition of water (c) dehydrogenation of ethane or ethylene (d) conversion of graphite to diamond
Problem 28
Which of the following statements is false? (a) work is a state function (b) temperature is a state function (c) change of state is completely denned when initial and final states are specified. (d) work appears at the boundary of the solution.
Problem 29
Molar heat capacity of water in equilibrium with ice at constant pressure is (a) zero (b) infinity (c) \(40.45 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\) (d) \(75.48 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\)
Problem 30
Standard molar enthalpy of formation of \(\mathrm{CO}_{2}\) is equal to (a) zero (b) the standard molar enthalpy of combustion of gaseous carbon. (c) the sum of standard molar enthalpies of formation Of \(\mathrm{CO}\) and \(\mathrm{CO}_{2}\) (d) the standard molar enthalpy of combustion of carbon (graphite)
Problem 32
\(\mathrm{H}_{2} \mathrm{~S}(\mathrm{~g}) \longrightarrow \mathrm{HS}(\mathrm{g})+\mathrm{H}(\mathrm{g}), \Delta \mathrm{H}^{\circ}=\mathrm{x}_{1}\) \(\Delta \mathrm{H}_{\mathrm{f}}^{\circ}\left[\mathrm{H}_{2} \mathrm{~S}(\mathrm{~g})\right]=\mathrm{x}_{2}, \Delta \mathrm{H}_{\mathrm{f}}^{\circ}[\mathrm{H}(\mathrm{g})]=\mathrm{x}_{3}\) hence, \(\Delta \mathrm{H}_{\mathrm{f}}^{\mathrm{a}}(\mathrm{HS})\) is (a) \(\mathrm{x}_{1}+\mathrm{x}_{2}-\mathrm{x}_{3}\) (b) \(x_{3}-x_{1}-x_{2}\) (c) \(\mathrm{x}_{1}-\mathrm{x}_{2}-\mathrm{x}_{3}\) (d) \(\mathrm{x}_{3}-\mathrm{x}_{1}+\mathrm{x}_{2}\)
Problem 33
Classify each of the following processes as spontaneous or non-spontaneous. I. \(\mathrm{H}_{2} \mathrm{O}(1) \longrightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{g}), \mathrm{T}=25^{\circ} \mathrm{C}\) vessel open to atomsphere with \(50 \%\) relative humidity. II. \(\mathrm{H}_{2} \mathrm{O}(\mathrm{s}) \longrightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{l}), \mathrm{T}=25^{\circ} \mathrm{C}, \mathrm{P}=\mathrm{l} \mathrm{atm}\) (a) I and II are both non-spontaneous (b) I and II are both spontaneous (c) I is non-spontaneous and II is spontaneous (d) I is spontaneous and II is non-spontaneous
Problem 34
The Gibbs free energy is defined as (a) \(\mathrm{G}=\mathrm{H}-\mathrm{T} \cdot \mathrm{S}\) (b) \(\mathrm{G}=\mathrm{H}+\mathrm{T} \cdot \mathrm{S}\) (c) \(\mathrm{G}=\mathrm{E}-\mathrm{T} . \mathrm{S}\) (d) \(\mathrm{G}=\mathrm{E}+\mathrm{TS}\)
Problem 35
Which of the following statement is true for \(\Delta \mathrm{G} ?\) (a) it is always proportional to \(\Delta \mathrm{H}\) (b) it may be less than or greater than or equal to \(\Delta \mathrm{H}\) (c) it is always greater than \(\Delta \mathrm{H}\) (d) it is always less than \(\Delta \mathrm{H}\)
