Separating Mixtures

• Mixtures consist of two or more elements or compounds, which are not chemically combined
• The components of a mixture retain their own properties, e.g. in a mixture of iron and sulfur, the iron is still magnetic and the sulfur is still yellow
• Mixtures can be separated by physical processes - these processes do not involve chemical reactions and do not produce new substances
• Filtration is used to separate soluble solids from insoluble solids, e.g. a mixture of salt (soluble) and sand (insoluble) can be separated by dissolving the salt in water and then filtering the mixture
• Crystallisation is used to obtain a soluble solid from a solution, e.g. salt crystals can be obtained from a solution of salty water:

  1. The mixture is gently warmed
  2. The water is evaporated leaving crystals of pure salt
• Simple distillation is used to obtain a solvent from a solution
• Fractional distillation is used to separate mixtures in which the components have different boiling points, e.g. oxygen and nitrogen can be obtained from liquid air by fractional distillation because they have different boiling points
• Chromatography is used to separate the different soluble, coloured components of a mixture, e.g. the different colours added to a fizzy drink can be separated by chromatography