a. One kilogram of steam contained in a horizontal frictionless piston and cylinder is heated at a constant pressure of 1.013 bar from 125°C to such a temperature that its volume doubles. Calculate the amount of heat that must be added to accomplish this change, the final temperature of the steam, the work the steam does against its surroundings, and the internal energy and enthalpy changes of the steam for this process. 

b. Repeat the calculation of part (a) if the heating occurs at a constant volume to a pressure that is twice the initial pressure.

c. Repeat the calculation of part (a) assuming that steam is an ideal gas with a constant-pressure heat capacity of 34.4 J/mol K. 

d. Repeat the calculation of part (b) assuming steam is an ideal gas as in part (c).