In solution, Cp refers to the molar heat capacity under constant pressure, and refers to the heat changed by changing the unit temperature under the condition of constant gas pressure. Cp=Cv (constant volume molar heat capacity) +R (universal gas constant). The internal energy changes U=nCvT, and the work is W=pV=nRT. Add up to Q=U+W=n(Cv+R)T=nCpT.