a) Calculate the changes in enthalpy per mole when iso-butane initially in an ideal gas state (at 1.1 bar and 180 K) is taken into final state at 550 K and 25 bar using the Redlich-Kwong equation. (10 Marks) b) Estimate the fugacity of nitrogen at 100 K and 45 bar and compare result with value taken from a suitable generalized correlation when the pressure was reduced to 10 bar. At 100 K the vapor pressure of nitrogen is 5.784 kPa