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Online Separation Techniques

The document discusses various techniques for separating mixtures, including filtration, evaporation, crystallization, distillation, chromatography, and sublimation. Each technique exploits differences in physical properties like solubility, boiling point, or ability to sublime. Examples are given of applying these techniques to separate mixtures like sand and water, salt and water, oil and water, as well as separating components of crude oil, air, and ink.

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Text by Mrs Teo Video clips taken from school video repository
Instructions 1. You have learnt that a mixture is made up of components not chemically combined together. Thus the components can be separated by several methods. 2. Go through this lesson package on the various separation techniques. 3. Follow up by reading your textbook.
1. A mixture is made up of components not chemically combined together, e.g. ink, fizzy drinks, mineral water, crude oil, air 2. The components of a mixture can be separated by several methods or techniques. 3. Each separation technique makes use of differences in the physical properties of the components
The Different Separation Techniques are as follows: • Magnetic attraction • Filtration • Evaporation • Crystallisation • Distillation • Chromatography
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 1.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 http://vle.hci.edu.sg/chemistry/beijing/expt%20techniques/lesson5.html
Filtration • used to separate (i) an insoluble solid from a liquid in a solid-liquid mixture e.g. sand from a mixture of sand and water sand) (water that passes through filter paper)
Filtration • (ii) used to separate an insoluble solid from a soluble solid e.g. insoluble calcium carbonate from soluble copper(II) sulphate
Filtration • insoluble solid that remains on the filter paper - residue • liquid that passes through- filtrate (filtrate can be water, any other solvent, or a solution)
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 (solute) that does not decompose on heating from a solution, 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 hair-dryer • obtaining common salt from the sea
Crystallisation • process to obtain a solid that decomposes on heating from its solution e.g. sugar crystals from sugar solution and copper(II) sulfate crystals from copper(II) sulfate solution
Procedure of Crystallisation 1. Pour the solution, e.g. copper (II) sulfate solution, into an evaporating dish. 2. Heat the solution to evaporate away the solvent until some solid starts to appear or a saturated solution is obtained. 3. Leave the solution to cool. 4. On cooling crystals of the solute that can no longer disssolve in the solution will be deposited as crystals. 5. Filter the mixture to collect the crystals which will be the residue.
Simple Distillation • process used to separate a pure liquid (solvent) from a solid-liquid solution e.g. pure water can be distilled from soft drinks, sea-water, etc
Distillation
Simple Distillation • solution boiled in distilling flask and vapour/steam cooled and condensed in a Liebig condenser • condenser consists of jacket of cold water with coldest water entering bottom of jacket and circulating out through the top ensuring that coldest part of condenser is just before the vapour escapes and that the jacket is completing full of water • condensed solvent – distillate • all impurities left in distilling flask • anti-bumping granules/boiling chips/beads-ensure even boiling
Fractional Distillation • process can be used to separate miscible liquids with different boiling points • liquid with lower boiling point will vaporise first e.g. to separate alcohol and water
Fractional Distillation
Industrial Applications of Fractional Distillation • oil refineries - separating the various components of crude oil or petroleum
Industrial Applications of Fractional Distillation •industries supplying oxygen to hospitals, shipyards, etc – separating the components of air
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. YouTube video clip
Applications •analysing ink dyes for forgery cases •analysing •analysing food dyes to ensure that •analysing only permitted colourings are used in foodstuffs •checking whether pesticides on vegetables exceed safe levels •detecting trace levels of drugs in •detecting urine samples
Sublimation - process by which a substance changes from solid state to vapour state on heating - e.g of substances which sublime - iodine - ammonium chloride On heating, they do not melt. Iodine changes into a beautiful violet vapour while ammonium chloride changes into a white vapour. They change back into solid crystals on cooling.
Sublimation - process used to separate a solid that sublimes from one that does not e.g. iodine or ammonium chloride from common salt
Sublimation When a mixture of a solid that sublimes and a solid that does not is heated, the solid that sublimes will turn into a vapour and separates from the other solid which remains in the container.
The End
ACE Suggestions 1. Production of whisky by distillation of barley mash
ACE Suggestions 2. Commercial Production of sodium chloride by: (i) Mining (ii) Evaporation of sea water