Determine the change in the enthalpy of helium, in kJ/kg, as it undergoes a change of state from 100 kPa and 20oC to 600 kPa and 300oC using the equation of state P(V − a) = RT where a =0.01 m3 /kg, and compare the result to the value obtained by using the ideal gas equation of state. (ANSWER: 1459 kJ/kg, 1454 kJ/kg)