$2.4 \mathrm{~g}$ coal is burnt in a bomb calorimeter in excess of oxygen at $298 \mathrm{~K}$ and $1 \mathrm{~atm}$ pressure. The temperature of the calorimeter rises from $298 \mathrm{~K}$ to $300 \mathrm{~K}$. The enthalpy change during the combustion of coal is $-x \mathrm{~kJ} \mathrm{~mol}^{-1}$. The value of $x$ is ___________. (Nearest Integer)
(Given : Heat capacity of bomb calorimeter $20.0 \mathrm{~kJ} \mathrm{~K}^{-1}$. Assume coal to be pure carbon)
Answer (integer)
200
Solution
$\mathrm{Q}($ Heat evolved $)=-\frac{\mathrm{C}_{\text {system }} \Delta \mathrm{T}}{\mathrm{n}}$
<br/><br/>
$\mathrm{n}_{\text {coal }}=\frac{2.4}{12}$
<br/><br/>
$\mathrm{Q}=\frac{-20(300-298)}{0.2}$
<br/><br/>
$Q=-200 \mathrm{~kJ} / \mathrm{mol}$
<br/><br/>
$x=200$
About this question
Subject: Chemistry · Chapter: Thermodynamics · Topic: Zeroth and First Law
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