Hi all , I have 2 questions, I dunno how to derive the equations, please help. Thank you. 1)A reversible adiabatic expansion of 2.5 moles or He from a volume 9L at 300K to a final volume of 28L. Find work(W), heat(Q), internal energy(U) and enthalpy change(H) and final temperature. (He is a monatomic ideal gas) 2)A reversible isobaric expansion of an ideal gas from P1,V1,T1 to P1,V2,T2, assume Cv = 5/2nR Find W, change in internal energy, Heat and enthalpy. I know for #1 heat = 0, therefore delta U = W = integral P*dV, but I don't know since we don't know pressure , I don't know how to continue. For #2, it is constant pressure, therefore W= -P*delta V delta U = Q - (p*delta V) Q = delta U + (p*delta V) = enthalpy Am I right ? it looks so weird, I need some help thanks !