Text by Mrs TeoVideo 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

The Different Separation Techniques are as follows:

• Magnetic attraction• Filtration• Evaporation• Crystallisation• Distillation• Chromatography

•• used used to separate to separate magneticmagneticmaterials,materials, e.g. iron, steel, nickel, e.g. iron, steel, nickel, cobalt cobalt from from nonnon--magneticmagnetic ones in a ones in a mixturemixture

e.g. separating iron filings from e.g. separating iron filings from sulphursulphur powderpowder

Magnetic AttractionMagnetic Attraction

1.1.ElectromagnetsElectromagnets are are used to used to removeremovesteel and iron scrapsteel and iron scrapat the junkat the junk--yard.yard.

Applications of Magnetic AttractionApplications of Magnetic Attraction

2.2. In hospitals, In hospitals, magnetsmagnets are often used are often used to to remove iron splintersremove iron splinters from apatientpatient’’s eyes.s eyes.

Using a Separating FunnelUsing a Separating Funnel

•• can be used to can be used to separate two separate two

immiscible liquidsimmiscible liquids,, such as oilsuch as oil

and waterand 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

mixturee.g. sand from a mixture of sand and water

(water that passes through filter paper)

sand)

Filtration

• (ii) used to separate an insoluble solid froma soluble solid

e.g. insoluble calcium carbonate fromsoluble copper(II) sulphate

Filtration

• insoluble solid that remains on the

filter paper - residueresidue

• liquid that passes through- filtratefiltrate

(filtrate can be water, any other (filtrate can be water, any other solvent, or a solution)solvent, or a solution)

• 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

• hair in our nostrils

trap the dust particles that we breathe in trap the dust particles that we breathe in and allow only clean air to pass throughand allow only clean air to pass through

• air filters in air conditioners

remove solid impurities from airremove solid impurities from air

• oil and air filters in cars

remove solid impurities found in engine remove solid impurities found in engine oil and airoil and air

Applications of FiltrationApplications of Filtration

• used to separate a dissolved solid (solute) that does not decompose on heating from a solution,

e.g. common salt from a salt solution

•• used to used to separate a dissolved solid separate a dissolved solid (solute)(solute) that that does notdoes not decomposedecompose on on heating heating from a solution,,

e.g. common salt from a salt solutione.g. common salt from a salt solution

Evaporation to drynessEvaporation to dryness

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.

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.

Procedure of Evaporating a SolutionProcedure of Evaporating a Solution

• drying wet clothes

• drying hair with a hair-dryer

• obtaining common salt from the sea

•• drying wet clothes drying wet clothes

•• drying hair with a hairdrying hair with a hair--dryerdryer

• obtaining common salt from the seaobtaining common salt from the sea

Applications of Evaporation

• process to obtain a solid thatdecomposes on heating from its solution

e.g. sugar crystals from sugar solution and copper(II) sulfatecrystals from copper(II) sulfate solution

•• process to obtain a solid thatdecomposes on heating from its solution

e.g. sugar crystals from sugar solution and copper(II) sulfatecrystals from copper(II) sulfate solution

Crystallisation

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.

• 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

•• 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

Simple DistillationSimple Distillation

Distillation

Simple DistillationSimple 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

• 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

• 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 DistillationFractional Distillation

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

Industrial Applications of Fractional Distillation

1. to separate the different colouredcomponents that make up black ink2. to detect tiny amounts of drugs or certain other chemicals in urine samples

1. to separate the different 1. to separate the different colouredcolouredcomponentscomponents that make up that make up black inkblack ink

2. to detect 2. to detect tiny amounts of drugstiny amounts of drugs or or certain other chemicals in certain other chemicals in urine samples

Paper Chromatography

• process used to separate the different components in a liquid mixture

For example it can be usedFor example it can be used

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

1. Apply a small but concentrated1. Apply a small but concentratedspot of the solution on a piece of spot of the solution on a piece of chromatography paper.chromatography paper.2. Suspend the chromatography2. Suspend the chromatographypaper in a beaker or boiling tube of paper in a beaker or boiling tube of solvent with the spot above the solvent with the spot above the level of the solvent.level of the solvent.

Paper ChromatographyPaper Chromatography

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 ChromatographyPaper 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.

Paper ChromatographyPaper 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 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

Applications

••analysinganalysing ink dyes for forgery casesink dyes for forgery cases

••analysinganalysing food dyes to ensure that food dyes to ensure that only permitted only permitted colouringscolourings are used are used in foodstuffsin foodstuffs

•checking whether pesticides on vegetables exceed safe levels

••detecting trace levels of drugs in detecting trace levels of drugs in urine samples 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 changesinto a beautiful violet vapour while ammoniumchloride changes into a white vapour.They change back into solid crystals on cooling.

- process used to separate a solid that sublimes from one that does note.g. iodine or ammonium chloride from common salt

Sublimation

When a mixture of a solid that sublimesand a solid that does not is heated, thesolid that sublimes will turn into a vapourand separates from the other solid which remains in the container.

Sublimation

The End

ACE Suggestions1. Production of whisky by distillation of barley mash

ACE Suggestions2. Commercial Production of sodium chloride by:

(i) Mining

(ii) Evaporation of sea water