Thermodynamics and Thermochemistry - Result Question 38
38. The difference between heats of reaction at constant pressure and constant volume for the reaction
$2 C _6 H _6(l)+15 O _2 \longrightarrow 12 CO _2(g)+6 H _2 O(l)$
at $25^{\circ} C$ in $kJ$ is
(a) $-7.43$
(b) $+3.72$
(c) $-3.72$
(d) $+7.43$
(1991,1 M)
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Answer:
Correct Answer: 38. (a)
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 $ $J=-7.43$ $ kJ$
BETA
