Methane (ideal gas with variable heat capacity) is contained in a piston-cylinder arrangement at a

temperature of 100Cand a pressure of 150kPa (state 1).

The gas is compressed in a polytropic process (n = 1.25) to a pressure of 400 kPa(state 2).

The initial volume is 1 3.

Calculate :

(a)The work required for this process in kJ(

b)The change in the internal energy of the gas in kJ

(c)The heat transfer during this process in kJ

(d)Argue, that in order to determine the heat transfer you need to start from first principles (use 1stlaw of thermodynamics)