Chlorine gas is to be heated from 120°C and 1 atm to 180°C.

(a) Calculate the heat input (kW) required to heat a stream of the gas flowing at 15.0 kmol/min at constant pressure.

(b) Calculate the heat input (kJ) required to raise the temperature of 15.0 kmol of chlorine in a closed rigid vessel from 120°C and 1 atm to 180°C. (Suggestion: Evaluate ΔU directly from the result of the first calculation, so that you do not have to perform another integration.) What is the physical significance of the numerical difference between the values calculated in Parts (a) and (b)?

(c) To accomplish the heating of Part (b), you would actually have to supply an amount of heat to the vessel greater than the amount calculated. Why?