Calculation of ∆U and ∆H:
For one mole of an ideal gas,
we have, CV = dU / dT
dU = C.dT
For a finite change,
we have, ∆U = (U2 – U1) = CV (T2 – T1)
and for n moles of an ideal gas we get
∆U = nCV (T2 – T1 ) …….(1)
We know,
∆H = ∆(U + PV)
∆H = ∆U + ∆(PV)
∆H = ∆U + ∆RT [∴ PV= RT]
∆H = ∆U + R∆T
∆H = CV (T2 – T1) + R (T2 – T1)
∆H = (CV + R) (T2 – T1 )
∆H = CP(T2 – T1) [∴C – C = R]
For n moles of an ideal gas we get
∆H = nCP (T2 – T1) ……..(2)
