Question

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 is 20.0 kJ K-1. Assume coal to be pure carbon)

Answer 1

$Q$(Heat evolved)$=−\frac {C_{system}ΔT}{n}$

$n_{coal}=\frac {2.4}{12}$
$n_{coal} = 0.2$
$Q=−\frac {20(300−298)}{0.2}$
$Q=−200$ kJ/mol
Given that, the enthalpy change during the combustion of coal is –x kJ mol–1
On comparing , we get
$x=200$

So, the answer is $200$.