Three-component System 5r5k6v

Three – Component System

The purpose of this experiment is to determine the solubility limits in a system made up of water and two other liquids, one or both of which are only partially miscible with water and to plot the solubility curve of the given three-component system. Eight 20-gram solutions containing 10 %, 25 %, 40 %, and 60 % by weight of acetic acid in water and acetic acid in benzene were prepared at a constant temperature of 25 °C, The solutions were titrated to cloudiness with benzene and with water, respectively. The percent composition of each component was computed and plotted on a ternary diagram.

1. Introduction A phase diagram shows the phases existing in equilibrium at any given condition. According to the phase rule, a maximum of four intensive variables (intensive properties)

must be specified to completely define the state of a three-component system. The intensive variables that are usually chosen are pressure, temperature, and concentration. For a three-component system at constant pressure and temperature, the solubility relations of the system can be represented using an equilateral triangle. The percentage of each component is represented by the perpendicular distance from the side opposite one apex to any point on the diagram, and each pure component is represented by each vertex of the triangle. 2. Materials and Methods 2.1 Materials and Apparatus The materials used in this experiment are component A (water), 75 ml of component B (Acetic acid), and 100 ml of component C (benzene). The apparatus used are the thermometer, 2 burettes, 8 glass-stoppered bottles (50 ml). 1 5-ml pipette. 2.2 Methods Solutions of known concentrations were prepared containing 10%, 25%, 40%, and 60% by weight of acetic acid in water. Twenty grams of each solution was prepared and placed in a 50-mL glass-stoppered bottle. A constant temperature of 25 °C was set and the solution was titrated with the third component, benzene. The solution was shaken vigorously after each addition of the titrant. The end point of the titration was taken to be the first appearance of perceptible cloudiness. Solutions containing 10%, 25%, 40%, and 60% by weight of acetic acid in benzene were prepared. The solutions were titrated to cloudiness with water at a constant temperature of 25 °C. The percent by weight of each component present at the appearance of the second phase was calculated and plotted on a ternary diagram. A smooth curve was drawn through the points. On the diagram, a point designated as M lying in the heterogeneous region about midway between the center of the region and one side of the bounding curve was selected. A 50-mL sample, with a composition corresponding to the selected point on the diagram, was prepared and shaken vigorously for several minutes. The sample

was then allowed to stand until two separate layers were formed. With the aid of a separatory funnel, each layer was run into a weighted flask. The weight of each solution was determined to the nearest twentieth of a gram. One ml of water was added to each sample to determine the water-rich phase. The water-rich solution was to remain homogeneous after the addition of water and the other is to become heterogeneous after the addition of water. 3.

Results