Liquid nitrogen is useful for medical purposes and for research laboratories. determine the minimum shaft work needed to liquefy nitrogen initially at 298 k and 1 atm to ending with saturated liquid at the normal boiling point, 77.4 k and 1 atm. the heat of vaporization at the normal boiling point is 5.577 kj/mol, and the surroundings are at 298 k. the constant pressure heat capacity of gaseous nitrogen can be assumed to be 7/2r and independent of temperature. consider nitrogen entering a flow device at 1 mol/min. give shaft work in kw.