Problem 12.11: The laboratory division of your company has sent you the following data for the system n-pentane (1) propionaldehyde (2) at 35 °C: The activity coefficients of the two components at infinite dilution are 4.0 and the saturation pressures of the pure components are 0.7 and 1 bar, respectively.
a) Does this system exhibit positive, negative, or no deviations from ideal-solution behavior?
b) Assuming the validity of the Margules equation, determine the constants A12 and A21 .
c) You suspect that this system forms an azeotrope. What is the composition of the two phases and the pressure at the azeotrope?
d) Draw a qualitative Pxy graph at 35 °C. On the graph show all the information that you have for this system.
e) Your are designing a single flash separation process for a stream that contains 45% n-pentane (the rest is propionaldehyde). The mixture is to be flashed at 35 °C and you must determine the pressure so that the purity of n-pentane is 95%. What is this pressure?