Distillation
This method is used to separate a liquid-liquid mixture by heating them where one liquid has a lower boiling point than the other. This means the liquid with lower boiling point boils earlier and evaporates faster leaving the other liquid. This method is used in purifying alcohols and also separating petrol from crude oil.
How to perform distillation
• Pour a mixture of alcohol and water into a beaker or container tightly sealed.
• Make a hole in the cover and pass one end of a tube through it.
• Put the other end in another container
• Make sure that the middle part of the tube in a cold water to condense the gaseous alcohol.
• Heat the mixture gently over.
• Observe how drops of alcohol fall into the other container.
Observation
Raw alcohol was gathered in the other container leaving the water behind. This happened because alcohol has a lower boiling point (78oC) than that of water (100oC).
Other methods of separation include flotation where iron filings sink in water leaving saw dust. Melting is used in the mining industry to separate the metal from dust.
