I. INTRODUCTION

A Phase Diagram is a type of chart

used to show conditions such as Pressure,

Temperature and Volume at which

thermodynamically distinct phases occur

and coexist at equilibrium. Common

components of a phase diagram are Lines

of Equilibrium or Phase Boundaries which

refers to the line that mark conditions under

which multiple phases can coexist at

equilibrium while a Triple points are points on

the phase diagrams where lines of equilibr ium intersects, triple points mark

conditions at which three different phases can coexist.

The Gibbs Phase Rule cannot determine the Phase Diagram of a ternary

(Three Component) mixture in one phase because the Gibbs Phase Rule predicts

four degrees of freedom. A system of four variables cannot be graphically

represented on a paper, so study of ternary system are carried out at constant

temperature and pressure. This reduced the number of degrees of freedom to two;

such system can be represented using the method of Gibbs and Roozeboom

method.

The equilibrium diagram for a ternary system at a constant temperature and

pressure can be represented in two dimensions. The Gibbs-Roozeboom method

uses a symmetrical representation for three components in a plane namely an

Equilateral Triangle.

Figure 1: Gibbs-Roozeboom diagram

II. METHODOLOGY

List of chemicals/materials:

Water

Butanol

Acetic acid

List of apparatus and set-up:

5 Erlenmeyer flasks (250 mL)

3 Pipette (10 mL) and aspirator

3 beakers (100 mL)

Burette and burette holder

Start

Prepare five 25mL solutions, each

containing the acetic acid and water with

varying concentrations.

Calculate the volume of A and B. Titrate each

solution with butanol. Note the volume of

butanol.

Compute the % w/w composition of the final

mixtures using the densities of acetic acid,

butanol and water.

Titrate with water. Note the volume of water.

Prepare 25 mL solutions, each

containing acetic and butanol with varying

concentrations.

Using % w/w composition of the final

mixtures.

Sketch the binodal curve in Gibbs-

Roozeboom diagram.

End