1. Tardigrade
  2. Question
  3. Chemistry
  4. 2.4 g coal is burnt in a bomb calorimeter in excess of oxygen at 298 K and 1 atm pressure. The temperature of the calorimeter rises from 298 K to 300 K. The enthalpy change during the combustion of coal is - x kJ mol -1. The value of x is . (Nearest Integer) (Given: Heat capacity of bomb calorimeter 20.0 kJ K -1. Assume coal to be pure carbon)

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Q. $2.4 \,g$ coal is burnt in a bomb calorimeter in excess of oxygen at $298 \,K$ and $1 \,atm$ pressure.
The temperature of the calorimeter rises from $298 \,K$ to $300 \,K$. The enthalpy change during the combustion of coal is $- x\, kJ \,mol ^{-1}$. The value of $x$ is __________. (Nearest Integer)
(Given : Heat capacity of bomb calorimeter $20.0 \,kJ \,K ^{-1}$. Assume coal to be pure carbon)

JEE MainJEE Main 2022Thermodynamics

Solution:

$C ( s )+ O _2( g ) \rightarrow CO _2( g ) ; \Delta H =- x\, kJ / mole$
$ Q = C \Delta T =20 \,kJ \times 2$
$40\, kJ$ heat is released for $2.4 g$ of $C$
For $1$ mole '$C$' :
$Q=\frac{40}{2.4} \times 12$
$=\frac{400}{24} \times 12=200\,kJ / mole$
$Q =\Delta E =\Delta H =200\, kJ \left(\because \Delta n _{ g }=0\right)$
$ x =200$