Fractional Distillation
Introduction
Fractional distillation is a laboratory technique used to separate liquid mixtures based on differences in their boiling points. It is a more precise method of distillation than simple distillation and can be used to separate mixtures with boiling points that are close together.Basic Concepts
Fractional distillation relies on the principle that liquids with different boiling points vaporize at different temperatures. The mixture to be separated is heated in a distillation flask, and the vapors are condensed in a condenser. The condensed liquid is then collected in a receiver. The vapors of the liquid with the lowest boiling point will condense first, followed by the vapors of the liquid with the next highest boiling point, and so on.Equipment and Techniques
The equipment used in fractional distillation includes a distillation flask, a condenser, a thermometer, and a receiver. The distillation flask is heated using a heating mantle or a hot plate. The condenser is a long, coiled tube that is cooled by running water. The thermometer is used to measure the temperature of the vapors in the distillation flask. The receiver is a flask or beaker that is used to collect the condensed liquid.The technique of fractional distillation involves heating the mixture to be separated in the distillation flask. As the mixture heats, the vapors of the liquid with the lowest boiling point will begin to condense in the condenser. The condensed liquid is then collected in the receiver. The temperature of the vapors in the distillation flask is monitored using the thermometer. When the temperature of the vapors reaches the boiling point of the next highest boiling liquid, the condensed liquid will begin to change composition. The liquid in the receiver should be changed at this point to collect the new liquid.
Types of Experiments
Fractional distillation can be used to separate a variety of different liquid mixtures. Some common types of experiments that use fractional distillation include:Separating a mixture of water and ethanol Separating a mixture of two hydrocarbons
* Separating a mixture of three or more liquids
Data Analysis
The data from a fractional distillation experiment can be used to determine the boiling points of the liquids in the mixture. The boiling point of a liquid is the temperature at which its vapor pressure is equal to the atmospheric pressure. The boiling point of a liquid can be determined by plotting a graph of the temperature of the vapors in the distillation flask versus the volume of the condensed liquid. The boiling point of the liquid is the temperature at which the graph changes slope.Applications
Fractional distillation has a wide variety of applications in chemistry and industry. Some common applications include:Purifying liquids Separating liquids with close boiling points
Analyzing the composition of liquids Producing chemicals and fuels