Liquid-liquid miscibility of three liquid system and one tie line

Liquid-Liquid Miscibility of three liquid system and position of one tie line

Liquid-liquid miscibility of three liquid system is based on the phase rules. It is sometimes necessary to know the mutual solubilities of liquids in a two-phase system. For example, you may need to know how much water is dissolved in an organic liquid substance with which it is in contact, as well as the amount of the organic compound that is in the aqueous phase, with which water is in contact. In this experiment we will consider a three-component mixture (Chloroform – water – acetic acid at 25 oC and barometric pressure) and construct the corresponding ternary phase diagram.

According to the face rule, a single face in the three-component system (Chloroform – water – acetic acid at 25 oC and barometric pressure) may posses four degree of freedom.

F= C-P+2 ——————–(1)

where, F= degree of freedom. C = component. P= Phase

These are temperature, pressure and the compositions of the two of the three components. Because of the difficulty in graphically so many variables, temperature and pressure are generally held constant, so the face rule reduced to

F=C-P=3-P—————-(2)

Do you get it that, this is the same special form of the face rule that is applies to the two component system (e.g. one of the liquid is A and another one is B) of constant pressure only.

Graphical Representation of the Three Component system:

For three component system, the properties of equilateral triangle provides a convenient means of representing the composition of a three component system at constant temperature and pressure. Line AB represents the compositions of all the system that can be prepared from from pure A as well as B. At the point P the system is 60%B and 40% A.

Chemicals and Apparatus:

Five Stopped bottle, burette, Acetic acid, chloroform, water, etc.

Procedure:

• Make 20g of mixture of CHCl3 and CH3COOH of varying composition in nine different stopped bottle with 10, 20, 30, 40, 50, 60, 70, 80, 90% CHCl3 by weight. The density of CHCl3 and CH3COOH are 1.50 and 1.05 respectively.
• Now add water into the solution from the burette with continuous shaking until the turbidity appears in the stopped bottles.
• From the amount of water added and the initial amount of CHCl3 and CH3COOH, the percentage of composition of the mixture are calculated as well as the results are plotted in a triangle diagram.
• Note the room temperature.

Data for liquid-liquid miscibility of three liquid system:

Data is in the image.