Internal energy of a system is the energy possessed by the system due to molecular motion and molecular configuration. Internal energy u=uk+up For an ideal gas there is no molecular attraction up=0 ∴ Internal energy u=uk (i.e., internal kinetic energy) and u=uk=23μRT At constant pressure (ΔQ)P=μCpΔT At constant volume (ΔQ)v=μCvΔT As C P>CV∴(ΔT)P<(ΔT)V