For nitrogen gas (diatomic, Cv = 20.8 J/(mol K)): (a) Find Cp using Mayer's relation. (b) How much heat is needed to raise 2.0 mol of nitrogen by 50 K at constant volume? (c) At constant pressure? Solution: (a) Cp = Cv + R = 20.8 + 8.31 = 29.1 J/(mol K). (b) Qv = n Cv delta_T = (2.0)(20.8)(50) = 2080 J. (c) Qp = n Cp delta_T = (2.0)(29.1)(50) = 2910 J. The extra 830 J = n R delta_T went into expansion work.