Separation Techniques Text by Mrs Teo Video clips taken from school video repository

The Different Separation Techniques are as follows: Magnetic attraction Filtration Evaporation Crystallisation Distillation Chromatography Note: The physical method used will depend on the nature of the constituents.

Magnetic Attraction used to separate magnetic materials, e.g. iron, steel, nickel, cobalt from non-magnetic ones in a mixture e.g. separating iron filings from sulphur powder.

Applications of Magnetic Attraction Electromagnets are used to remove steel and iron scrap at the junk-yard. 2. In hospitals, magnets are often used to remove iron splinters from a patient’s eyes.

Using a Separating Funnel can be used to separate two immiscible liquids, such as oil and water.

Filtration used to separate an insoluble solid from (i) a liquid in a solid-liquid mixture e.g. sand from a mixture of sand and water or (ii) a soluble solid e.g. calcium carbonate from mixture of it and copper(II) sulphate.

Filtration insoluble solid that remains on the filter paper - residue. liquid that passes through- filtrate.

Applications of Filtration hair in our nostrils trap the dust particles that we breathe in and allow only clean air to pass through air filters in air conditioners remove solid impurities from air oil and air filters in cars remove solid impurities found in engine oil and air

Evaporation to dryness used to separate a dissolved solid that does not decompose on heating from a solution, e.g. common salt from a salt solution.

Procedure of Evaporating a Solution 1. Pour the solution into an evaporating dish. 2. Heat the solution to dryness to evaporate away the solvent, leaving behind the solute. 3. Make the Bunsen flame smaller when almost all the solvent has been evaporated away to reduce spitting.

Applications of Evaporation drying wet clothes drying hair with a hair-dryer obtaining common salt from the sea

Crystallisation process to obtain a solid that decomposes on heating from its solution. e.g. sugar from sugar solution and copper(II) sulphate crystals from copper(II) sulphate solution

Distillation process used to separate a liquid (solvent) from a solid-liquid solution or liquid-liquid solution. e.g. pure water can be distilled from soft drinks

Distillation

Fractional Distillation process can be used to separate miscible liquids with different boiling points liquid with lower boiling point will vaporize first e.g. to separate alcohol and water

Industrial Applications of Fractional Distillation oil refineries - separating the various components of crude oil or petroleum industries supplying oxygen to hospitals, shipyards, etc – separating the components of air

Fractional Distillation

Paper Chromatography process used to separate the different components in a liquid mixture For example it can be used 1. to separate the different coloured components that make up black ink 2.to detect tiny amounts of drugs or certain other chemicals in urine samples.

Paper Chromatography 1. Apply a small but concentrated spot of the solution on a piece of chromatography paper. 2. Suspend the chromatography paper in a beaker or boiling tube of solvent with the spot above the level of the solvent.

Paper Chromatography 3. Separation takes place because some components of the liquid mixture travel at a faster pace than other components on the paper or any other absorbent material.

Paper Chromatography 3. As the solvent travels up the paper, the mixture is separated into its respective components. A chromatogram of the separated components is obtained.

Applications analysing ink dyes for forgery cases analysing food dyes to ensure that only permitted colourings are used in foodstuffs checking whether pesticides on vegetables exceed safe levels detecting trace levels of drugs in urine samples

The End

ACE Suggestion 1. Production of whisky by distillation of barley mash

ACE Suggestion 2. Commercial Production of sodium chloride by: (i) Mining (ii) Evaporation of sea water