The heat capacity at constant pressure of hydrogen cyanide is given by the expression CpJ/ mol°C 35:3 0:0291T °C (a) Write an expression for the heat capacity at constant volume for HCN, assuming ideal-gas behavior. (b) Calculate ΔH^(J/mol) for the constant-pressure process HCN v; 25°C; 0:80 atm ! HCN v; 200°C; 0:80 atm (c) Calculate ΔU^(J/mol) for the constant-volume process HCN v; 25°C; 50 m3 /kmol ! HCN v; 200°C; 50 m3 /kmol (d) If the process of Part (b) were carried out in such a way that the initial and final pressures were each 0.80 atm but the pressure varied during the heating, the value of ΔH^ would still be what you calculated assuming a constant pressure. Why is this so