In rubbish dumps, we use strong magnets to separate things containing iron from plastics and glass. This makes it easier to recycle materials.
Electrostatics work in a similar way to magnets. They attract specific particles away. They are used in cleaning to attract lint and fluff as well as photocopiers to attract toner to the paper.
Evaporation
When you heat a mixture, you’ll notice steam coming off it. This is a good method to remove all the water from the mixture. We use this when we are cooking sauce to make it thicker. This situation is called ‘ reduction’.
The video to the left, shows what is left after removing all the water from coke.
Distillation
Distillation uses evaporation and condensation. We heat the liquid, forming vapours, then condense the vapours into a liquid form.
As we heat salt water, the water converts into a gas. The gas rises up and is sent through a condenser. As the gas travels it cools down, becoming a liquid again (condensing). At the end we have salt and water in separate beakers.
If we want to separate 2 different liquids from each other, this is called fractional distillation.
Crystallisation
Crystallisation is a technique which chemists use to purify solid compounds. If we heat a liquid up and add crystallising solutes (salt, sugar or alum) to it, we create a saturated solution. When slowly cooled, the solutes in the solution slow down and begin to bump into each other, this is called Nucleation.
More and more solutes molecules bump into each other, eventually forming large crystals.
As we know, mixtures can be made up of multiple compounds. We can use chromatography to separate these mixtures into its core components.
Chromatography works because different substances in a mixture flow at different speeds over a solid surface. The solid surface is a special type of paper called chromatogram.
Complex machines use chromatography during drug analysis.
