Thermodynamics and Thermochemistry 1 Question 35
38. The difference between heats of reaction at constant pressure and constant volume for the reaction
$$ 2 \mathrm{C}{6} \mathrm{H}{6}(l)+15 \mathrm{O}{2} \longrightarrow 12 \mathrm{CO}{2}(g)+6 \mathrm{H}_{2} \mathrm{O}(l) $$
at $25^{\circ} \mathrm{C}$ in $\mathrm{kJ}$ is
(a) -7.43
(b) +3.72
(c) -3.72
(d) +7.43
$(1991,1 \mathrm{M})$
Objective Questions II
(One or more than one correct option)
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Solution:
- $\Delta H=\Delta E+\Delta n_{g} R T \Rightarrow \Delta H-\Delta E=\Delta n_{g} R T=-3 R T$
$$ =-3 \times 8.314 \times 298=-7433 \mathrm{~J}=-7.43 \mathrm{~kJ} $$
