The yield of the product in the reaction

${\mathrm{A}}_2\left(\mathrm{g}\right) + 2\mathrm{B}\left(\mathrm{g}\right) \rightleftharpoons \mathrm{C}\left(\mathrm{g}\right) + \mathrm{Q} \mathrm{kJ} \mathrm{would} \mathrm{be} \mathrm{higher} \mathrm{at}$

• high temperature and high pressure

• high temperature and low pressure

• low temperature and high pressure

• low temperature and low pressure

Given that $∆{\mathrm{H}}_{\mathrm{f}}$(H) = 218 kJ / mol, express the H-H bond energy in kcal/mol.

• 52.15

• 911

• 104

• 52153

$$\begin{gathered} \mathrm{Calculate} ∆\mathrm{H}° \mathrm{for} \mathrm{the} \mathrm{reaction}, \\ {\mathrm{Na}}_2\mathrm{O}\left(\mathrm{s}\right) + {\mathrm{SO}}_3\left(\mathrm{g}\right) \to {\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{g}\right) \\ \mathrm{given} \mathrm{the} \mathrm{following}: \\ \left(\mathrm{A}\right) \mathrm{Na}\left(\mathrm{s}\right) +{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \to \mathrm{NaOH}\left(\mathrm{s}\right) + \frac{1}{2}{\mathrm{H}}_2\left(\mathrm{g}\right) ;∆\mathrm{H}°= -146 \mathrm{kJ} \\ \left(\mathrm{B}\right) {\mathrm{Na}}_2{\mathrm{SO}}_4\left(\mathrm{s}\right) +{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \to 2 \mathrm{NaOH}\left(\mathrm{s}\right) + {\mathrm{SO}}_3\left(\mathrm{g}\right); ∆\mathrm{H}°=+ 418 \mathrm{kJ} \\ \left(\mathrm{C}\right) 2 {\mathrm{Na}}_2\mathrm{O}\left(\mathrm{s}\right) +2 {\mathrm{H}}_2\left(\mathrm{g}\right) \to 4\mathrm{Na}\left(\mathrm{s}\right) + 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right); ∆\mathrm{H}°= +259 \mathrm{kJ} \end{gathered}$$

• +823 kJ

• -581 kJ

• -435 kJ

• +531 kJ

64.

If an endothermic reaction occurs spontaneously at constant temperature (T) and pressure (p), then which of the following is true?

• $∆\mathrm{G} > 0$

• $∆\mathrm{H} < 0$

• $∆\mathrm{S} > 0$

• $∆S < 0$

A spontaneous process is one in which the system suffer

• no energy change

• a lowering of free energy

• a lowering of entropy

• an increase in internal energy

When a solid melts reversibly :

• H decreases

• G increases

• E decreases

• S increases

Enthalpy is equal to :

• ${\mathrm{T}}^2{\left[\frac{\partial (\mathrm{G}/\mathrm{T})}{\partial \mathrm{T}}\right]}_P$

• $-{\mathrm{T}}^2{\left[\frac{\partial (\mathrm{G}/\mathrm{T})}{\partial \mathrm{T}}\right]}_{\mathrm{P}}$

• ${\mathrm{T}}^2{\left[\frac{\partial (\mathrm{G}/\mathrm{T})}{\partial \mathrm{T}}\right]}_V$

• $-{\mathrm{T}}^2{\left[\frac{\partial (\mathrm{G}/\mathrm{T})}{\partial \mathrm{T}}\right]}_{\mathrm{V}}$

Condition for spontaneity in an isothermal process is

• $∆\mathrm{A} + \mathrm{W} < 0$

• $∆\mathrm{G} + \mathrm{U} <0$

• $∆\mathrm{A} + \mathrm{U}>0$

• $∆\mathrm{G} -\mathrm{U}<0$

$$\begin{gathered} 2\mathrm{C}\left(\mathrm{s}\right) + 2{\mathrm{O}}_2\left(\mathrm{g}\right) \to 2{\mathrm{CO}}_2\left(\mathrm{g}\right); ∆\mathrm{H}= -787 \mathrm{kJ} ....\left(\mathrm{i}\right) \\ {\mathrm{H}}_2\left(\mathrm{g}\right) + \frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right) \to {\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right); ∆\mathrm{H} = -286 \mathrm{kJ} ...\left(\mathrm{ii}\right) \\ {\mathrm{C}}_2{\mathrm{H}}_2\left(\mathrm{g}\right) + 2\frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right) \to 2{\mathrm{CO}}_2\left(\mathrm{g}\right) + {\mathrm{H}}_2\mathrm{O} \left(\mathrm{l}\right) ; ∆\mathrm{H}= -1310 \mathrm{kJ} ...\left(\mathrm{iii}\right) \end{gathered}$$

The heat of formation of acetylene is :

• -1802 kJ

• +1802 kJ

• +237 kJ

• -800 kJ

The standard molar heat of formation of ethane, CO₂ and water (l) are -21.1, -94.1 and -68.3 kcal respectively. The standard molar heat of combustion of ethane will be

• -372 kcal

• 162 kcal

• -240 kcal

• 183.5 kcal