In the following take CV = 20.8 and CP = 29.1 Jmol1C1 for nitrogen gas:

(a) Three moles of nitrogen at 30C, contained in a rigid vessel, is heated to 250C.How much heat is required if the vessel has a negligible heat capacity? If the vessel weighs 100 kg and has a heat capacity of 0.5 kJkg1C1, how much heat is required? (b) Four moles of nitrogen at 200C is contained in a piston/cylinder arrangement. How much heat must be extracted from this system, which is kept at constant pres- sure, to cool it