Methods of Separating Mixtures (V)

DISTILLATION

This method of separation deals with the separation of two liquids with close boiling points. This is done by using a distillation apparatus. The liquids are mixed together. The liquid which evaporates first is trapped and collected into a measuring cylinder. The liquid collected is then condensed.

With the explanation above, let’s use an example to explain in order to give a better understanding.

Diagram

An example of mixture separated with this method is water mixed with alcohol. Water and alcohol is a uniform mixture. The liquid mixes must have different boiling points and the boiling points must be closed in order not to prolong the experiment. Alcohol has a lower boiling point than water. Alcohol will evaporate first when the mixture is heated. The first distillate is collected in the measuring cylinder and that is the alcohol. Water is left behind. The evaporated liquid is the alcohol and the liquid left behind is water.

This is mostly known as a simple distillation. This is mostly used in industry to manufacture alcoholic drinks.

An experiment of simple distillation is performed below:

Activity : Simple distillation.

Materials : Water, alcohol, beaker, distillation flask, measuring cylinder, source of heat (Bunsen heat).

Method:

Mix about 150cm³ of alcohol with 100cm³ of water in a beaker.
a. What do you observe?

Pour the mixture into a distillation flask fitted with a condenser.

Heat the mixture gently over the Bunsen burner.

Collect the distillate into a clean measuring cylinder.
b. Smell the liquid collected and record.