Chapter 6

The work done by a system is 10 joule, when 40 joule heat is supplied to it. What is the increase in internal energy of system? (a) \(30 \mathrm{~J}\) (b) \(50 \mathrm{~J}\) (c) \(40 \mathrm{~J}\) (d) \(20 \mathrm{~J}\)

The standard entropies of \(\mathrm{CO}_{2}(\mathrm{~g}), \mathrm{C}(\mathrm{s})\) and \(\mathrm{O}_{2}(\mathrm{~g})\) are \(213.5,5.74\) and \(205 \mathrm{~J} \mathrm{~K}^{-1}\) respectively. The standard entropy of the formation of \(\mathrm{CO}_{2}(\mathrm{~g})\) is (a) \(1.16 \mathrm{JK}^{-1}\) (b) \(2.76 \mathrm{JK}^{-1}\) (c) \(1.86 \mathrm{JK}^{-1}\) (d) \(2.12 \mathrm{JK}^{-1}\)

For a reaction at \(300 \mathrm{~K}\), enthalpy and entropy changes are \(-11.5 \times 10^{3} \mathrm{~J} \mathrm{~mol}^{-1}\) and \(-105 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) respec- tively. What is the change in Gibbs free energy? (a) \(25 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (b) \(30 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (c) \(15 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (d) \(20 \mathrm{kJmol}^{-1}\)

The standard enthalpy of decomposition of \(\mathrm{N}_{2} \mathrm{O}_{4}\) to \(\mathrm{NO}_{2}\) is \(58.04 \mathrm{~kJ}\) and standard entropy of this reaction is \(176.7 \mathrm{~J} \mathrm{~K}^{-1}\). The standard free energy change for this reaction at \(25^{\circ} \mathrm{C}\), is (a) \(5.39 \mathrm{~kJ}\) (b) \(-5.39 \mathrm{~kJ}\) (c) \(539 \mathrm{~kJ}\) (d) \(53.9 \mathrm{~kJ}\)

The entropy values in \(\mathrm{J} \mathrm{K}^{-1} \mathrm{~mol}^{-1}\) of \(\mathrm{H}_{2}(\mathrm{~g})=130.6\), \(\mathrm{Cl}_{2}(\mathrm{~g})=223\) and \(\mathrm{HC} 1(\mathrm{~g})=186.7\) at \(298 \mathrm{~K}\) and 1 atm pressure. Then entropy change for the reaction \(\mathrm{H}_{2}(\mathrm{~g})+\mathrm{Cl}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{HC} 1(\mathrm{~g})\) is (a) \(+540.3\) (b) \(+727.3\) (c) \(-166.9\) (d) \(+19.8\)

2 moles of an ideal gas is expanded isothermally and reversibly from 1 litre of 10 litre at \(300 \mathrm{~K}\). The enthalpy change (in \(\mathrm{kJ}\) ) for the process is (a) \(11.4 \mathrm{~kJ}\) (b) \(-11.4 \mathrm{~kJ}\) (c) \(0 \mathrm{~kJ}\) (d) \(4.8 \mathrm{~kJ}\).

The enthalpy of vaporization of a liquid is \(30 \mathrm{~kJ} \mathrm{~mol}^{-1}\) and entropy of vaporization is \(5 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}\). The boiling point of the liquid at 1 atm is (a) \(250 \mathrm{~K}\) (b) \(400 \mathrm{~K}\) (c) \(450 \mathrm{~K}\) (d) \(600 \mathrm{~K}\)

Which of the following reaction defines \(\Delta \mathrm{H}_{\mathrm{f}}^{\circ}\) ? (a) \(\mathrm{C}\) (diamond) \(+\mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CO}_{2}(\mathrm{~g})\) (b) \(1 / 2 \mathrm{H}_{2}(\mathrm{~g})+1 / 2 \mathrm{~F}_{2}(\mathrm{~g}) \longrightarrow \mathrm{HF}(\mathrm{g})\) (c) \(\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{NH}_{3}(\mathrm{~g})\) (d) \(\mathrm{CO}(\mathrm{g})+1 / 2 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CO}_{2}(\mathrm{~g})\)

If the standard entropies of \(\mathrm{CH}_{4}, \mathrm{O}_{2}, \mathrm{CO}_{2}\) and \(\mathrm{H}_{2} \mathrm{O}\) are \(186.2,205.3,213.6\) and \(69.96 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\) respectively, then standard entropy change for the reaction \(\mathrm{CH}_{4}(\mathrm{~g})+2 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CO}_{2}(\mathrm{~g})+2 \mathrm{H}_{2} \mathrm{O}\) (1) is (a) \(-215.6 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\) (b) \(-243.3 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\) (c) \(-130.5 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\) (d) \(-85.6 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\)

The standard entropy change for the reaction \(\mathrm{SO}_{2}(\mathrm{~g})+1 / 2 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{SO}_{3}(\mathrm{~g})\) is (where \(\mathrm{S}^{\circ}\) for \(\mathrm{SO}_{2}(\mathrm{~g}), \mathrm{O}_{2}(\mathrm{~g})\) and \(\mathrm{SO}_{3}(\mathrm{~g})\) are \(248.5,205\) and \(256.2\) \(\mathrm{J} \mathrm{K}^{-1} \mathrm{~mol}^{-1}\) respectively) (a) \(198.2 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\) (b) \(-192.8 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\) (c) \(-94.8 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\) (d) \(94.8 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\)

In thermodynamics, a process is called reversible when (a) surroundings and system change into each other (b) there is no boundary between system and surroundings (c) the surroundings are always in equilibrium with the system (d) the system changes into the surroundings sponta neously

Identify the state function among the following: (a) \(\mathrm{Q}\) (b) \(\mathrm{Q}-\mathrm{w}\) (c) \(\mathrm{Q} / \mathrm{w}\) (d) \(\mathrm{Q}+\mathrm{w}\)

For a reaction at \(300 \mathrm{~K}\), enthalpy and entropy changes are \(-11.5 \times 10^{3} \mathrm{~J} \mathrm{~mol}^{-1}\) and \(-105 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) respectively. What is the change in Gibbs free energy? (a) \(25 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (b) \(30 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (c) \(15 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (d) \(20 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

For the reaction \(\mathrm{H}_{2}(\mathrm{~g})+1 / 2 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{H}_{2} \mathrm{O}(\mathrm{l})\) the value of \(\Delta \mathrm{H}=-285.8 \mathrm{~kJ} \mathrm{~mol}^{-1}\) and \(\Delta \mathrm{S}=0.163\) \(\mathrm{JK}^{-1} \mathrm{~mol}^{-1}\). The free energy change at \(300 \mathrm{~K}\). for the reaction, is (a) \(-289.6 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (b) \(437.5 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (c) \(-334.7 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (d) \(-291.6 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

For an endothermic reaction, where \(\Delta \mathrm{H}\) represents the enthalpy of the reaction in \(\mathrm{kJ} / \mathrm{mol}\), the minimum value for the energy of activation will be (a) less than \(\Delta \mathrm{H}\) (b) zero (c) more than \(\Delta \mathrm{H}\) (d) equal to \(\Delta \mathrm{H}\).

Which of the following equations represent standard heat of formation of \(\mathrm{C}_{2} \mathrm{H}_{4} ?\) (a) \(2 \mathrm{C}\) (diamond) \(+2 \mathrm{H}_{2}(\mathrm{~g}) \longrightarrow \mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{~g})\) (b) \(2 \mathrm{C}\) (graphite) \(+2 \mathrm{H}_{2}(\mathrm{~g}) \longrightarrow \mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{~g})\) (c) \(2 \mathrm{C}\) (diamond) \(+4 \mathrm{H}(\mathrm{g}) \longrightarrow \mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{~g})\) (d) \(2 \mathrm{C}\) (graphite) \(+4 \mathrm{H}(\mathrm{g}) \longrightarrow \mathrm{C}_{2} \mathrm{H}_{4}(\mathrm{~g})\)

The enthalpy change \((\Delta \mathrm{H})\) for the reaction, \(\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \longrightarrow 2 \mathrm{NH}_{3}(\mathrm{~g})\) is \(-92.38 \mathrm{~kJ}\) at 298 \(\mathrm{K}\). The internal energy change \(\Delta \mathrm{U}\) at \(298 \mathrm{~K}\) is (a) \(-92.38 \mathrm{~kJ}\) (b) \(-87.42 \mathrm{~kJ}\) (c) \(-97.34 \mathrm{~kJ}\) (d) \(-89.9 \mathrm{~kJ}\)

The work done by a system is 10 joule, when 40 joule heat is supplied to it. What is the increase in internal energy of system? (a) \(30 \mathrm{~J}\) (b) \(50 \mathrm{~J}\) (c) \(40 \mathrm{~J}\) (d) \(20 \mathrm{~J}\)

The increase in internal energy of the system is 100 when \(300 \mathrm{~J}\) of heat is supplied to it. What is the amount of work done by the system (a) \(-200 \mathrm{~J}\) (b) \(+200 \mathrm{~J}\) (c) \(-300 \mathrm{~J}\) (d) \(-400 \mathrm{~J}\)

What is the value of \(\Delta \mathrm{E}\), when \(64 \mathrm{~g}\) oxygen is heated from \(0^{\circ} \mathrm{C}\) to \(100^{\circ} \mathrm{C}\) at constant volume? \(\left(\mathrm{C}_{\mathrm{v}}\right.\) on an average is \(5 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) ) (a) \(1500 \mathrm{~J}\) (b) \(1800 \mathrm{~J}\) (c) \(2000 \mathrm{~J}\) (d) \(2200 \mathrm{~J}\)

To calculate the amount of work done in joules during a reversible isothermal expansion of an ideal gas, the volume must be expressed in (a) \(\mathrm{dm}^{3}\) only (b) \(\mathrm{m}^{3}\) only (c) \(\mathrm{cm}^{3}\) only (d) any one of them

If \(0.75\) mole of an ideal gas is expanded isothermally at \(27^{\circ} \mathrm{C}\) from 15 litres to 25 litres, then work done by the gas during this process is \(\left(\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right)\) (a) \(-1054.2 \mathrm{~J}\) (b) \(-896.4 \mathrm{~J}\) (c) \(-954.2 \mathrm{~J}\) (d) \(-1254.3 \mathrm{~J}\)

The entropy change when \(36 \mathrm{~g}\) of water evaporates at \(373 \mathrm{~K}\) is \(\left(\Delta \mathrm{H}=40.63 \mathrm{~kJ} \mathrm{~mol}^{-1}\right)\) (a) \(218 \mathrm{~J} \mathrm{~K}^{-\mathrm{t}}\) (b) \(150 \mathrm{~J} \mathrm{~K}^{-1}\) (c) \(118 \mathrm{~J} \mathrm{~K}^{-1}\) (d) \(200 \mathrm{~J} \mathrm{~K}^{-1}\)

The standard entropies of \(\mathrm{CO}_{2}(\mathrm{~g}), \mathrm{C}(\mathrm{s})\) and \(\mathrm{O}_{2}(\mathrm{~g})\) are \(213.5,5.74\) and \(205 \mathrm{JK}^{-1}\) respectively. The standard entropy of the formation of \(\mathrm{CO}_{2}(\mathrm{~g})\) is (a) \(1.16 \mathrm{~J} \mathrm{~K}^{-1}\) (b) \(2.76 \mathrm{~J} \mathrm{~K}^{-1}\) (c) \(1.86 \mathrm{~J} \mathrm{~K}^{-1}\) (d) \(2.12 \mathrm{~J} \mathrm{~K}^{-1}\)

If the standard entropies of \(\mathrm{CH}_{4}(\mathrm{~g}), \mathrm{H}_{2} \mathrm{O}(\mathrm{g}), \mathrm{CO}_{2}(\mathrm{~g})\) and \(\mathrm{H}_{2}(\mathrm{~g})\) are \(186.2,188.2,197.6\) and \(130.6 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) respectively, then the standard entropy change for the reaction \(\mathrm{CH}_{4}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \longrightarrow \mathrm{CO}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g})\) is (a) \(215 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) (b) \(225 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) (c) \(145 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) (d) \(285 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\)

Two moles of an ideal gas are compressed at \(300 \mathrm{~K}\) from a pressure of 1 atm to a pressure of 2 atm. The change in free energy is (a) \(5.46 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (b) \(2.46 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (c) \(3.46 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (d) \(8.46 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

In monoatomic gases, ratio of specific heat at constant pressure to that at constant volume is (a) \(3 / 5\) (b) \(5 / 3\) (c) \(7 / 5\) (d) \(4 / 5\)

The standard entropies of \(\mathrm{H}_{2}(\mathrm{~g}), \mathrm{I}_{2}(\mathrm{~s})\) and \(\mathrm{HI}(\mathrm{g})\) are \(130.6,116.7\) and \(206.3 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\) respectively. The change in standard entropy in the reaction \(\mathrm{H}_{2}(\mathrm{~g})+\mathrm{I}_{2}(\mathrm{~s}) \longrightarrow 2 \mathrm{HI}(\mathrm{g})\) is (a) \(185.6 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) (b) \(170.5 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) (c) \(169.5 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) (d) \(165.9 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\)

In the reaction: \(\mathrm{CO}(\mathrm{g})+1 / 2 \mathrm{O}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CO}_{2}(\mathrm{~g})\) the change in \(\Delta S^{\circ}\) is (given \(\mathrm{S}^{\circ}\) for \(\mathrm{CO}, \mathrm{O}_{2}\) and \(\mathrm{CO}_{2}\) are \(197.6,205.3\) and \(213.6 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) respectively) (a) \(-78.6 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) (b) \(-50 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) (c) \(-86.5 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\) (d) \(-30 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\)

One mole of an ideal gas is allowed to expand reversibly and adiabatically from a temperature of \(27^{\circ} \mathrm{C}\). If work done during the process is \(3 \mathrm{~kJ}\), then final temperature of the gas is \(\left(\mathrm{C}_{\mathrm{v}}=20 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}\right)\) (a) \(150 \mathrm{~K}\) (b) \(200 \mathrm{~K}\) (c) \(175 \mathrm{~K}\) (d) \(225 \mathrm{~K}\)

The change in entropy, in the conversion of one mole of water at \(373 \mathrm{~K}\) to vapour at the same temperature is (Latent heat of vaporization of water = \(\left.2.257 \mathrm{~kJ} \mathrm{~g}^{-1}\right)\) (a) \(99 \mathrm{JK}^{-1}\) (b) \(129 \mathrm{JK}^{-1}\) (c) \(89 \mathrm{JK}^{-1}\) (d) \(109 \mathrm{JK}^{-1}\)

The direct conversion of \(\mathrm{A}\) to \(\mathrm{B}\) is difficult, hence it is carried out by the following path: $$ \begin{aligned} &\text { Given }\\\ &\Delta \mathrm{S}(\mathrm{A} \longrightarrow \mathrm{C})=50 \mathrm{e} . \mathrm{u} .\\\ &\Delta \mathrm{S}(\mathrm{C} \longrightarrow \mathrm{D})=30 \mathrm{e} . \mathrm{u}\\\ &\Delta \mathrm{S}(\mathrm{B} \longrightarrow \mathrm{D})=20 \mathrm{e} . \mathrm{u} \end{aligned} $$ where e.u. is entropy unit then \(\Delta \mathrm{S}(\mathrm{A} \longrightarrow \mathrm{B})\) is (a) \(+100\) e.u. (b) \(+60\) e.u. (c) \(-100\) e.u. (d) \(-60\) e.u.

One mole of monatomic ideal gas at \(\mathrm{T}(\mathrm{K})\) is expanded from \(1 \mathrm{~L}\) to \(2 \mathrm{~L}\) adiabatically under a constant external pressure of 1 atm the final temperature of the gas in Kelvin is (a) \(\mathrm{T}\) (b) \(\frac{\mathrm{T}}{2^{5 / 3-2}}\) (c) \(\mathrm{T}-\frac{2}{3 \times 0.0821}\) (d) \(\mathrm{T}+\frac{3}{2 \times 0.0821}\)

One mole of a non-ideal gas undergoes a change of state \((2.0 \mathrm{~atm}, 3.0 \mathrm{~L}, 95 \mathrm{~K}) \longrightarrow(4.0 \mathrm{~atm}, 5.0 \mathrm{~L}\) \(245 \mathrm{~K}\) ) with a change in internal energy, \(\Delta \mathrm{U}=30.0 \mathrm{~L}\) atm. The change in enthalpy \((\Delta \mathrm{H})\) of the process in \(\mathrm{L}\) atm is (a) \(40.0\) (b) \(42.3\) (c) \(44.0\) (d) not defined, because pressure is not constant

The \(\Delta \mathrm{H}_{\mathrm{f}}^{\circ}\) for \(\mathrm{CO}_{2}(\mathrm{~g}), \mathrm{CO}(\mathrm{g})\) and \(\mathrm{H}_{2} \mathrm{O}(\mathrm{g})\) are \(-393.5\), \(-110.5\) and \(-241.8 \mathrm{~kJ} \mathrm{~mol}^{-1}\) respectively. The standard enthalpy change (in \(\mathrm{kJ}\) ) for the reaction \(\mathrm{CO}_{2}(\mathrm{~g})+\mathrm{H}_{2}(\mathrm{~g}) \longrightarrow \mathrm{CO}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g})\) is (a) \(524.1\) (b) \(41.2\) (c) \(-262.5\) (d) \(-41.2\)

Anhydrous \(\mathrm{AlCl}_{3}\) is covalent. From the data given below, predict whether it would remain covalent or become ionic in aqueous solution (ionization energy of \(\mathrm{Al}=5137 \mathrm{kJmol}^{-1} \Delta \mathrm{H}_{\text {hydrtion }}\) for \(\mathrm{Al}^{+3}=-4665 \mathrm{~kJ}\) \(\mathrm{~mol}^{-1}, \Delta \mathrm{H}_{\text {thydatica }}\) for \(\left.\mathrm{Cl}^{-}=-381 \mathrm{~kJ} \mathrm{~mol}^{-1}\right)\) (a) ionic (b) covalent (c) both (a) and (b) (d) none of these

An athlete is given \(100 \mathrm{~g}\) of glucose of energy equivalent to \(1560 \mathrm{~kJ}\). He utilizes \(50 \%\) of this gained energy in the event. In order to avoid storage of energy in the body, calculate the mass of water he would need to perspire. Enthalpy of \(\mathrm{H}_{2} \mathrm{O}\) for evaporation is \(44 \mathrm{~kJ} \mathrm{~mol}^{-1}\). (a) \(346 \mathrm{~g}\) (b) \(316 \mathrm{~g}\) (c) \(323 \mathrm{~g}\) (d) \(319 \mathrm{~g}\)

The standard enthalpy of combustion at \(25^{\circ} \mathrm{C}\) of \(\mathrm{H}_{2}\), \(\mathrm{C}_{6} \mathrm{H}_{10}\) and cyclohexane \(\left(\mathrm{C}_{6} \mathrm{H}_{12}\right)\) are \(-241,-3800\) and \(-3920 \mathrm{~kJ} \mathrm{~mol}^{-1}\) respectively. Calculate heat of hydrogenation of cyclohexane \(\left(\mathrm{C}_{6} \mathrm{H}_{10}\right) .\) (a) \(-161 \mathrm{kJmol}^{-1}\) (b) \(-131 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (c) \(-121 \mathrm{kJmol}^{-1}\) (d) none

Calculate the resonance energy of \(\mathrm{N}_{2} \mathrm{O}\) from the following data: \(\Delta \mathrm{H}_{\mathrm{f}}\) of \(\mathrm{N}_{2} \mathrm{O}=82 \mathrm{~kJ} \mathrm{~mol}^{-1} .\) Bond ener- gies of \(\mathrm{N} \equiv \mathrm{N}, \mathrm{N}=\mathrm{N}, \mathrm{O}=\mathrm{O}\) and \(\mathrm{N}=\mathrm{O}\) bonds are 946,418 498 and \(607 \mathrm{~kJ} \mathrm{~mol}^{-1}\) respectively. (a) \(-88 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (b) \(-170 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (c) \(-82 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (d) \(-258 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

Calculate \(\Delta H_{f}^{\circ}\) for chloride ion from the following data: \(1 / 2 \mathrm{H}_{2}(\mathrm{~g})+1 / 2 \mathrm{Cl}_{2}(\mathrm{~g}) \longrightarrow \mathrm{HCl}(\mathrm{g})\) \(\Delta \mathrm{H}_{\mathrm{f}}^{\circ}=-92.4 \mathrm{~kJ}\) \(\mathrm{HCl}(\mathrm{g})+\mathrm{nH}_{2} \mathrm{O}(\mathrm{l}) \longrightarrow \mathrm{H}^{+}(\mathrm{aq})+\mathrm{Cl}\) (aq) \(\Delta \mathrm{H}_{\mathrm{Hyd}}=-74.8 \mathrm{~kJ}\) \(\Delta \mathrm{H}_{f}\left[\mathrm{H}^{+}\right]=0.0 \mathrm{~kJ}\) (a) \(-189 \mathrm{~kJ}\) (b) \(-167 \mathrm{~kJ}\) (c) \(+167 \mathrm{~kJ}\) (d) \(-191 \mathrm{~kJ}\)

\(0.16 \mathrm{~g}\) of methane is subjected to combustion at \(27^{\circ} \mathrm{C}\) in a bomb calorimeter system. The temperature of the calorimeter system (including water) was found to rise by \(0.5^{\circ} \mathrm{C}\). Calculate the heat of combustion of methane at constant volume. The thermal capacity of the calorimeter system is \(177 \mathrm{~kJ} \mathrm{~K}^{-1}\left(\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right)\) (a) \(-695 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (b) \(-1703 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (c) \(-890 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (d) \(-885 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

At \(300 \mathrm{~K}\), the standard enthalpies of formation of \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{COOH}(\mathrm{s}), \mathrm{CO},(\mathrm{g})\) and \(\mathrm{H}_{2} \mathrm{O}\) (s) are \(-408,-393\) and \(-286 \mathrm{~kJ} \mathrm{~mol}^{-1}\) respectively. Calculate the heat of combustion of benzoic acid at constant volume. (a) \(-3296 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (b) \(-3200 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (c) \(-3201 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (d) \(-3603 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

The heat liberated on complete combustion of \(7.8 \mathrm{~g}\). benzene is \(327 \mathrm{~kJ}\). This heat was measured at constant volume and at \(27^{\circ} \mathrm{C}\). Calculate the heat of combustion of benzene at constant pressure \(\left(\mathrm{R}=8.3 \mathrm{~J} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}\right)\) (a) \(-3274 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (b) \(-1637 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (c) \(-3270 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (d) \(-3637 \mathrm{~kJ} \mathrm{~mol}^{-1}\)

The enthalpies of solution of \(\mathrm{BaCl}_{2}\) (s) and \(\mathrm{BaCl}_{2} \cdot 2 \mathrm{H}_{2} \mathrm{O}\) (s) are-20.6 and \(8.8 \mathrm{~kJ} \mathrm{~mol}^{-1}\) respectively. The enthalpy change for the hydration of \(\mathrm{BaCl}_{2}(\mathrm{~s})\) is (a) \(29.8 \mathrm{~kJ}\) (b) \(-11.8 \mathrm{~kJ}\) (c) \(-20.6 \mathrm{~kJ}\) (d) \(-29.4 \mathrm{~kJ}\).

For the reaction, \(\mathrm{A}(\mathrm{g})+2 \mathrm{~B}(\mathrm{~g}) \longrightarrow 2 \mathrm{C}(\mathrm{g})+3 \mathrm{D}(\mathrm{g})\) The value of \(\Delta \mathrm{H}\) at \(27^{\circ} \mathrm{C}\) is \(19.0 \mathrm{kcal}\). The value of \(\Delta \mathrm{E}\) for the reaction would be (given \(\mathrm{R}=2.0 \mathrm{cal} \mathrm{K}^{-\mathrm{t}} \mathrm{mol}^{-1}\) ) (a) \(20.8 \mathrm{kcal}\) (b) \(19.8 \mathrm{kcal}\) (c) \(18.8 \mathrm{kcal}\) (d) \(17.8 \mathrm{kcal}\)

Determine \(\Delta \mathrm{H}\) and \(\Delta \mathrm{E}\) for reversible isothermal evaporation of \(90 \mathrm{~g}\) of water at \(100^{\circ} \mathrm{C}\). Assume that water vapour behaves as an ideal gas and heat of evaporation of water is \(540 \mathrm{cal} \mathrm{g}^{-1}\left(\mathrm{R}=2.0 \mathrm{cal} \mathrm{mol}^{-1} \mathrm{~K}^{-1}\right)\) (a) \(48600 \mathrm{cal}, 44870 \mathrm{cal}\) (b) \(43670 \mathrm{cal}, 47700 \mathrm{cal}\) (c) 47700 cal, \(43670 \mathrm{cal}\) (d) \(44870 \mathrm{cal}, 48670 \mathrm{cal}\)

\(\Delta \mathrm{G}^{\circ}\) for the reaction, \(\mathrm{x}+\mathrm{y} \rightleftharpoons \mathrm{z}\) is \(-4.606 \mathrm{kcal}\). The value of equilibrium constant of the reaction at \(227^{\circ} \mathrm{C}\) is (a) \(0.01\) (b 100 (c) 2 (d) 10

The standard heat of combustion of \(\mathrm{Al}\) is \(-837.8 \mathrm{~kJ}\) \(\mathrm{mol}^{-1}\) at \(25^{\circ} \mathrm{C}\). If Al reacts with \(\mathrm{O}_{2}\) at \(25^{\circ} \mathrm{C}\), which of the following releases \(250 \mathrm{kcal}\) of heat? (a) the reaction of \(0.312 \mathrm{~mol}\) of \(\mathrm{Al}\) (b) the formation of \(0.624\) mol of \(\mathrm{Al}_{2} \mathrm{O}_{3}\) (c) the reaction of \(0.712\) mol of \(\mathrm{Al}\) (d) the formation of \(0.615 \mathrm{~mol}\) of \(\mathrm{Al}_{2} \mathrm{O}_{3}\)

The dissociation energies of \(\mathrm{CH}_{4}\) and \(\mathrm{C}_{2} \mathrm{H}_{6}\) to convert them into gaseous atoms are 360 and \(620 \mathrm{kcal} \mathrm{mol}\) respectively. The bond energy of \(\mathrm{C}-\mathrm{C}\) bond is (a) \(280 \mathrm{kcal} \mathrm{mol}^{-1}\) (b) \(240 \mathrm{kcal} \mathrm{mol}^{-1}\) (c) \(160 \mathrm{kcal} \mathrm{mol}^{-1}\) (d) \(80 \mathrm{kcal} \mathrm{mol}^{-1}\)

Calculate \(\mathrm{Q}\) and \(\mathrm{W}\) for the isothermal reversible expansion of one mole of an ideal gas from an initial pressure of \(1.0\) bar to a final pressure of \(0.1\) bar at a constant temperature of \(273 \mathrm{~K}\). (a) \(5.22 \mathrm{~kJ},-5.22 \mathrm{~kJ}\) (b) \(-27.3 \mathrm{~kJ}, 27.3 \mathrm{~kJ}\) (c) \(27.3 \mathrm{~kJ},-27.3 \mathrm{~kJ}\) (d) \(-5.22 \mathrm{~kJ}, 5.22 \mathrm{~kJ}\)