1. The problem statement, all variables and given/known data calculate the change of entropy (for the system) when 3 moles of a monatomic perfect gas, for which Cp,m = (5/2) R, is heated and compressed from 298K and 1atm to 398K and 5atm. ans: -22.1 JK-1 2. Relevant equations for an ideal gas, Pv=nRT for iso-choric condition, delta S = Cv ln(T2/T1) 3. The attempt at a solution as both the P and T increase, by Pv=nRT v should be constant at this case so i thought i should use Cv ln(T2/T1) however the model answer is that it uses nCp,m ln(T2/T1) + nRln(V2/V1) i dont know which part of my concept is wrong... pls help, thank you!