I was asked to find the change in specific enthalpy of constant volume process. Mass of 10 kg of a gas is heated to a pressure of about 2 times the initial pressure. The initial temperature was 20°C. The process is a reversible, non-flow, constant volume process. I found out the final temperature which is 40°C Change in enthalpy Δh=Cp*Δt My question is, is it correct to use Cp which is defined for a constant pressure process in a constant volume process? If it's correct then how it is correct?