A mixture is two or more substances (elements or compounds) not chemically combined together.
have a fixed composition. have no fixed composition.
are separated by chemical reactions. are separated by physical means.
are chemically combined together. are not chemically combined together.
To separate a mixture, you can use physical means. They all rely on differences between the physical properties of the substances in the mixture:
Filtration separates substances that are insoluble in a particular solvent from those soluble in the solvent.
- Collect the sand on filter paper.
- Wash with distilled water to remove any salt solution left on it.
- Dry in a warm oven to evaporate any water off and leave the pure sand.
Crystallisation separates a solid that has dissolved in a liquid and made a solution.
- Evaporate the water from the solution by heating it in an evaporating dish on a water bath.
- Stop when the solution crystallises.
- Leave the water to evaporate off at room temperature.
Simple distillation separates two liquids with different boiling points.
- A solution is heated and boiled to evaporate the solvent.
- The vapour given off enters the condenser, cools back, and turns back into a liquid for collection.
- Any dissolved solids will remain in the heated flask.
That is all for part 1!