Separating Mixtures 2
Chemistry: AQA GCSE Higher, topic 1.1.7
Distillation
Distillation is a special technique used to separate mixtures of liquids. It uses the different boiling points of liquids to separate them. There are 2 types of distillation:
Simple distillation
- Separates 2 liquids with different boiling points.
- The mixture is heated until the liquid with the lower boiling point starts to boil.
- The vapour released passes through a condenser, where the gas cools back into a liquid.
- Simple distillation can also separate a solute from a solvent, when the solvent has a lower boiling point than the solute.
Fractional distillation
- Separates lots of liquids with different boiling points.
- The mixture is slowly heated until the liquid with the lowest boiling point boils and then condenses.
- Then we increase temperature slowly to collect (boil then condense) the other fractions.
Test yourself on Separating Mixtures 2
Why must a thermometer be used to monitor the temperature during simple distillation?
A mixture contains four liquids, each with a different boiling point. Why would fractional distillation be used to separate this mixture instead of simple distillation?
A mixture of salt dissolved in water is heated using simple distillation. Water has a lower boiling point than salt. Why does this method separate the water from the salt?