In reactions involving solids and liquids (where change in volume is negligible), the heat of reaction at constant pressure as compared to that at constant volume is
A
More
B
Less
C
Same
D
Unpredictable; depends on the particular reaction
Correct Answer: Same
The $${C_P}$$ and $${C_V}$$ are the amount of heat required to raise the temperature of a gas by an $${1^ \circ }C$$ under constant pressure and constant volume respectively. Since in case of constant volume the entire heat is used for raising the temperature of the gas only no work is done but in case of constant pressure process some of the heat given is used for doing work also hence more amount of heat is required in case of constant pressure process to obtain the $${1^ \circ }C$$ change in temperature of the gas. But in case of solids and liquids since volume expansivity is small the $${C_P}$$ and $${C_V}$$ values remains same.