Separating mixtures

Separating mixtures into pure substances.

There are a variety of techniques that can be used to separate mixtures into pure substances. Eaxh method uses differences in the physical properties of the materials in the mixture to achieve separation.

Method of separation	Used to separate ...
Filtration	an insoluble solid from a liquid based upon differences in size. eg. clay from water
Evaporation	a soluble solid from a liquid based upon differences in boiling points. eg. salt from sea water
Crystallisation	two or more soluble solids from one another based upon differences in solubilities
Distillation	a solvent from a soluble soild based upon differences in boiling point. eg. water from sea water
Fractional distillation	miscible liquids from one another based upon differences in boiling point. eg. water and ethanol (alcohol)
Separating funnel	immiscible liquids from one another based upon differences in miscibility. eg. oil and water.
Magnetism	solids from one another based upon differences in their ferromagnetic properties. eg. aluminum and iron.
Paper chromatography	soluble substances from one another based upon differences in retention rates as a solvent moves over paper.
Decanting	an insoluble solid from a liquid by carefully pouring off the liquid. Based upon differences in density.

Mixtures

Mixtures are made up of many different types of particles. eg. conglomerate rock is a good example of a mixture. Dirt is also a mixture of different things. You can easily see the different types of particles.

Examples of chemical mixtures are solutions, suspensions, solids. The following picture is a mixture of copper sulfate and water.

Mixtures are defined as impure substances that can be separated into pure substances by physical process such as distillation, froth flotation, decanting, centrifuging, crystallization, fractional distillation, evaporation, filtration and chromatography.

Mixtures may be classified as homogeneous or heterogenous in nature.