The different substances in mixtures are usually easily separated from one another. The method you use depends upon the type of mixture you have.
Chromatography
This is good for separating dissolved substances that have different colours, such as inks and plant dyes. It works because some of the coloured substances dissolve in the liquid better than others, so they travel further up the paper.
Filtration
This is good for separating an insoluble solid from a liquid (an insoluble substance does not dissolve in water). For example, sand can be separated from a mixture of sand and water using filtration.
Evaporation
This is good for separating a soluble solid from a liquid (a soluble substance dissolves in water to form a solution). For example, copper sulphate crystals can be separated from copper sulphate solution using evaporation. Remember that it is the water that evaporates away, not the solution.
Simple distillation
This is good for separating a liquid from a solution. For example, water can be separated from salty water by simple distillation. This method works because the liquid evaporates from the solution, but is then cooled and condensed into a separate container. The salt does not evaporate and so it stays behind.
Fractional distillation
This is good for separating two or more liquids from each other. For example, ethanol (alcohol) can be separated from a mixture of ethanol and water by fractional distillation. This method works because the two liquids have different boiling points.
