Problem 11.5: A tank that contains a mixture of normal heptane (1)/normal octane is delivered to you. The composition of the mixture is unknown but the tank labels state that the bubble temperature of the mixture at 1 bar is 103 °C.

a) What is the composition of the mixture?

b) What is the dew temperature at 1 bar?

c) The mixture is to be flashed at 120 °C, 1.5 bar. Determine the recovery of normal heptane in the vapor stream.

d) You are requested to flash the mixture so that the liquid stream is 85% of the inlet (by mol). If the pressure is 1.5 bar, what temperature should be used?

Additional data: The saturation pressures of the two components are given by the Antoine equation:

where Psat is in mm Hg, t is in Kelvin, and the parameters Ai , Bi , Ci , are