How is distillation used to purify liquids?

Distillation purifies liquids by heating them to create vapour, then cooling the vapour to collect the purified liquid.

Distillation is a popular method used in chemistry to separate and purify liquids. The process relies on the different boiling points of the substances in a mixture. When a mixture is heated, the substance with the lower boiling point will vaporise first. This vapour is then directed into a condenser, where it is cooled and returns to its liquid state, effectively separating it from the other substances in the mixture.

The process begins with the liquid mixture being placed in a distillation flask. This flask is then heated, usually with a Bunsen burner or an electric heater. As the temperature rises, the substance with the lowest boiling point begins to vaporise. This vapour rises up the neck of the flask and into a condenser. The condenser is a long, coiled tube, usually surrounded by a water jacket to keep it cool. As the hot vapour enters the condenser, it cools down and condenses back into a liquid. This liquid, now purified, drips down into a separate container.

The remaining substances in the original flask continue to be heated. As each one reaches its boiling point, it too will vaporise and can be collected separately. This process can be repeated as many times as necessary to separate and purify all the substances in the mixture.

Distillation is a very effective method for purifying liquids, but it does have its limitations. It is most effective when the boiling points of the substances in the mixture are significantly different. If they are too close together, the substances may vaporise at the same time, making it difficult to separate them. Despite this, distillation remains a key technique in chemistry, used in everything from producing drinking water to making spirits.