Exploring Mixtures and their Separation
Choosing a separation method
Choose the right way to separate a mixture.
How to choose a method: find the property that is different between the parts of your mixture, then pick the method that uses it.
| Property that differs | Method |
|---|---|
| Size of particles | Filtration |
| Density | Separating funnel, centrifuge |
| Solubility | Crystallization |
| Boiling point | Distillation |
| One part sublimes | Sublimation |
| How fast parts move on paper | Chromatography |
Some mixtures need several steps. Sand + salt + naphthalene:
- Heat to sublime off the naphthalene.
- Add water to dissolve the salt, then filter out the sand.
- Evaporate the water to get the salt back.
Separation is not always possible: once lemonade is mixed, it is very hard to get its ingredients back.
Separation inside you. Your kidneys filter waste out of your blood all day. Donated blood is separated into plasma, platelets, and white and red cells, and stored in blood banks, so one donation can help several patients.
Separation in your town. Sewage treatment uses sedimentation, coagulation and filtration. The cleaned water can be reused for flushing toilets or watering plants.
Separation starts at home. Sort your waste into two bins:
- Dry waste (plastic, paper, glass, metal) is recycled.
- Wet waste (food scraps, peels) is composted.
Researchers can even recover lithium from old mobile and laptop batteries.
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