Problem 42
Hess's law is applicable for the determination of heat of (a) transition (b) formation (c) reaction (d) all of these.
Problem 43
The statement "The change of enthalpy of a chemical reaction is same whether the reaction takes place in one or several steps" is (a) Le Chatelier's law (b) van't Hoff's law (c) first law of thermodynamics (d) Hess's law.
Problem 45
What will be the enthalpy change of conversion of graphite into diamond? \(\begin{aligned} \text { Given } & C_{\text {graphite' }}, \Delta_{\text {comb }} H=&-391.25 \mathrm{k} \mathrm{F} ; \\ & \mathrm{C}_{\text {diamond }}, \Delta_{\text {comb }} H &=-393.12 \mathrm{~kJ} \end{aligned}\) (a) zero (b) \(-391.25 \mathrm{k} \mid\) (c) \(-393.12 \mathrm{~kJ}\) (d) \(-1.87 \mathrm{~kJ}\)
Problem 49
How much heat is evolved if \(3.2 \mathrm{~g}\) of methane is burnt and if the heat of combustion of methane is \(-880 \mathrm{~kJ} \mathrm{~mol}^{-1} ?\) (a) \(88 \mathrm{~kJ}\) (b) \(264 \mathrm{~kJ}\) (c) \(176 \mathrm{~kJ}\) (d) \(440 \mathrm{~kJ}\)
Problem 50
What will be the enthalpy of combustion of carbon to produce carbon monoxide on the basis of data given below: $$ \begin{aligned} &\mathrm{C}_{(s)}+\mathrm{O}_{2(g)} \rightarrow \mathrm{CO}_{2(g)}-393.4 \mathrm{~kJ} \\ &\mathrm{CO}_{(g)}+\frac{1}{2} \mathrm{O}_{2(g)} \rightarrow \mathrm{CO}_{2(g)}-283.0 \mathrm{~kJ} \end{aligned} $$ (a) \(+676.4 \mathrm{~kJ}\) (b) \(-676.4 \mathrm{~kJ}\) (c) \(-110.4 \mathrm{~kJ}\) (d) \(+110.4 \mathrm{~kJ}\)
Problem 54
The enthalpy of solution of sodium chloride is \(4 \mathrm{~kJ}\) \(\mathrm{mol}^{-1}\) and its enthalpy of bydration of ions is \(-784\) kJ mol \(^{-1}\). What will be the lattice enthalpy of sodium chloride? (a) \(+780 \mathrm{k} J \mathrm{~mol}^{-1}\) (b) \(+394 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (c) \(+788 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (d) \(+398 \mathrm{~kJ} \mathrm{~mol}^{-1}\)
Problem 57
The amount of heat evolved when \(0.50 \mathrm{~m}_{0} \mathrm{e}\) of \(\mathrm{HCl}\) is mixed with \(0.30\) mole of \(\mathrm{NaOH}\) solution is (a) \(57.1 \mathrm{~kJ}\) (b) \(28.55 \mathrm{~kJ}\) (c) \(11.42 \mathrm{~kJ}\) (d) \(17.13 \mathrm{~kJ}\)
Problem 60
What will be \(\Delta H\) for the reaction, \(\mathrm{CH}_{2} \mathrm{Cl}_{2} \rightarrow \mathrm{C}+2 \mathrm{H}+2 \mathrm{Cl} ?\) \(\left(B \cdot E\right.\). of \(\mathrm{C}-\mathrm{H}\) and \(\mathrm{C}-\mathrm{Cl}\) bonds are \(416 \mathrm{~kJ} \mathrm{~mol}^{-1}\) and \(325 \mathrm{~kJ} \mathrm{~mol}^{-1}\) respectively) (a) \(832 \mathrm{~kJ}\) (b) \(1482 \mathrm{~kJ}\) (c) \(650 \mathrm{~kJ}\) (d) \(1855 \mathrm{~kJ}\)
Problem 63
Bond energies of few bonds are given below: \(\mathrm{Cl}-\mathrm{Cl}=242.8 \mathrm{~kJ} \mathrm{~mol}^{-1}, \mathrm{H}-\mathrm{Cl}=431.8 \mathrm{~kJ} \mathrm{~mol}^{-\mathrm{l}}\) \(\mathrm{O}-\mathrm{H}=464 \mathrm{k} \mathrm{J} \mathrm{mol}^{-1}, \mathrm{O}=\mathrm{O}=442 \mathrm{k} \mathrm{J} \mathrm{mol}^{-1}\) Using the B.E., calculate \(\Delta H\) for the following reaction, \(2 \mathrm{Cl}_{2}+2 \mathrm{H}_{2} \mathrm{O} \rightarrow 4 \mathrm{HCl}+\mathrm{O}_{2}\) (a) \(906 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (b) \(172.4 \mathrm{k}] \mathrm{mol}^{-1}\) (c) \(198.8 \mathrm{~kJ} \mathrm{~mol}^{-1}\) (d) \(442 \mathrm{~kJ} \mathrm{~mol}^{-1}\)
Problem 73
Which of the following reactions will have the value of \(\Delta S\) with a negative sign? (a) \(\mathrm{H}_{2} \mathrm{O}_{(\mathrm{f})} \rightarrow \mathrm{H}_{2} \mathrm{O}_{(\mathrm{g})}\) (b) \(2 \mathrm{SO}_{2(g)}+\mathrm{O}_{2(x)} \rightarrow 2 \mathrm{SO}_{3(0)}\) (c) \(\mathrm{Cl}_{2(\underline{g})} \rightarrow 2 \mathrm{Cl}_{(g)}\) (d) \(\mathrm{CaCO}_{3(s)} \rightarrow \mathrm{CaO}_{(s)}+\mathrm{CO}_{2(g)}\)
