Picking a method
Show on a big screenMud in water. Blood in a tube. Oil on water. Each mixture needs its own method. A method uses a property of the parts. A property is a feature, such as size.
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The rule
Each method works on a property in which the parts differ. If the parts do not differ in it, the method fails.
Two liquids that do not mix are immiscible. They form layers. A separating funnel drains the lower layer first.
Oil floats because it is less dense than water. Less dense means lighter for the same volume.
| Method | Use it for | Property used |
|---|---|---|
| Filtration | Solid pieces in a liquid | Size: big pieces stay on the paper |
| Separating funnel | Two liquids that do not mix | Density: one layer floats |
| Centrifugation | Fine solid pieces, or blood parts | Spinning throws heavier parts to the bottom |
| Coagulation | Very fine pieces in water | Alum clumps them so they settle |
| Sublimation | A solid such as camphor | It turns straight to vapour when heated |
| Evaporation | A dissolved solid | The solvent turns to vapour |
| Distillation | Liquids that boil at different points | Boiling point |
| Chromatography | Dyes and pigments | Speed on wet paper |
In filtration, the liquid that passes through the paper is the filtrate. The pale liquid part of blood is plasma.
With sublimation, the solid changes to vapour without becoming a liquid. On cooling, the vapour turns back to solid. That is deposition.
Alum is also called fitkari. Camphor is also called kapoor. Dyes and pigments are the coloured substances in ink and paint. Lemon juice makes milk form paneer. That is coagulation too.
Try the lab to finish this lesson.