Mixture - GCSE Chemistry Definition

What is a mixture?

In GCSE chemistry, a mixture is a substance consisting of two or more elements or compounds which are not chemically joined. As a result, it is possible to separate a mixture by physical means. 

Methods used to separate mixtures include filtration, crystallisation, chromatography and distillation. The method used depends on the substance being separated. 

Filtration is used to separate a solid and liquid, so would be appropriate for a mixture of sand and water.  

Simple distillation can separate a pure substance from a mixture so could be used to separate water from salty water. 

Chromatography can separate mixtures of substances that have different solubilities, such as the colours in ink. 

Crystallisation involves separating a dissolved solid from a solution, for example, obtaining salt from water.