Chemical reaction is invariably associated with the transfer of energy either in the form of heat or light. In the laboratory, heat changes in physical and chemical processes are measured with an instrument called Calorimeter. Heat change in the process is calculated as :
q=msΔT ........ s=specificheat
=cΔT ....... c=heatcapacity
Heat of reaction at constant volume is measured using bomb Calorimeter.
qV=ΔU=internal energy change
Heat of reaction at constant pressure is measured using bomb Calorimeter.
qP=ΔH
qP=qV+PΔV
ΔH=ΔU+ΔnRT
The heat capacity of a bomb calorimeter is
500JK−1. When
0.1g of Methane was burnt in this calorimeter, the temperature rose by
2∘C. The value of
ΔU per mole will be :