9.8 = An equimolar mixture of propane and butane is initially in the liquid phase at T = 240 K and P=10 bar. The liquid flows through an adiabatic throttling valve that reduces its pressure telt = 0.8 bar, resulting in partial evapora- tion of the mixture. Calculate the temperature and vapor fraction of the mixed vapor + liquid stream exiting the throttling valve. State all assump- tions in your calculations