Liquid-Vapor Phase Equilibrium

Distillations will be performed in hood

Purpose

• To study the equilibrium of a binary non-ideal liquid-vapor system.

• To construct a standard curve for refractive index vs composition

• To construct a phase diagram.

• To determine the T and mol fraction of the azeotrope.

Liquid-Vapor Equilibrium

• An ideal solution obeys Raoult’s Law for all solution compositions. Water and 1-propanol are miscible but their solution does not obey Raoult’s Law.

• The boiling point of a binary solution depends on the composition of the solution. See Chang Chapter 5.

Experimental Procedure

• Construct a standard curve for refractive index vs solution composition. You will use a refractometer to do this.

• Carry out several distillations to find the boiling point of several equilibrium solutions.

• Construct T vs mol fraction phase diagram and find the azeotrope characteristics for the water and 1-propanol system.

Experimental Procedure

• You will carry out 11 distillations and collect a liquid and a vapor fraction for each one. Good organization, clean glassware, careful lab technique and group communication are essential for success.

• Assign duties to each group member before starting this experiment.