A pure substance is made up of only one

substance and is not mixed with any other

substance.

A mixture is a substance that contains two or

more substances that are not chemically

combined.

Purity of a substance can determined by

testing its melting and boiling points or

chromatography.

FIXED BOILING POINT FIXED MELTING POINT

A pure solid will melt

completely at a fixed

temperature.

Impurities lower the

melting point of a

substances.

Impurities cause

melting to occur over a

range of temperatures.

A pure solid will boil at

an exact and fixed

temperature.

Impurities higher the

boiling point of a

substances.

Impurities cause

boiling to occur over a

range of temperatures.

Separation method What it separates

Chromatography Compounds in a solution with same properties

Filtration Solids or group of solids and liquids in a mixture

Evaporation Solids that cannot decompose when heated in a solution

Crystallisation Dissolved solids in a solution

Simple Distillation Liquids in a solution

Fractional Distillation Mixture of miscible (dissolved) liquids

Separating Funnel Immiscible (undissolved) liquids

Sublimation Substances that sublime from two substances

Magnetic Attraction Magnetic substances from non-magnetic ones

Separation method Differences between objects

Chromatography Solubility with ethanol

Filtration Size of particles

Evaporation State of object (solid and liquid)

Crystallisation State of object (solid and liquid)

Simple Distillation Boiling points

Fractional Distillation Boiling points

Separating Funnel Both are immiscible

Sublimation Ability to sublime

Magnetic Attraction Magnetism

Chromatography

Apply a spot of food colouring to the

chromatography paper. Dip the chromato-

graphy paper in ethanol.

Ethanol dissolves the dyes and travels up the

paper, carrying the dyes along.

Coloured spots are left in different places of

the paper depending on the solubility of the

dye in ethanol.

Filtration

Place a piece of filter paper in a filter funnel.

Position a beaker under the filter funnel.

Pour the mixture into the filter funnel. The

liquid passes through the filter paper while the

insoluble solids does not pass through.

The filtrate will be collected in the beaker and

the residue remains on the filter paper.

Wash the residue with distilled water and let it

dry. Separation is complete.

Filtration

Place a piece of filter paper in a filter funnel.

Position a beaker under the filter funnel.

Pour the mixture into the filter funnel. The

liquid passes through the filter paper while the

insoluble solids does not pass through.

The filtrate will be collected in the beaker and

the residue remains on the filter paper.

Wash the residue with distilled water and let it

dry. Separation is complete.

Crystallisation

Crystillisation applies to all substances while

evaporation applies to substances that do not

decompose when heated strongly.

Set up an apparatus of a beaker of the solution.

Apply heat under the beaker with a bunsen

burner until a hot saturated solution is formed.

The solution is allowed to cool and the mixture

is then filtered. Separation is complete.

Simple Distillation

Place a distillation flask under a bunsen burner and connect it to a condenser. Cold running water is allowed to enter from the bottom condenser and leave from the top.

Allow the condenser to slope downwards towards a beaker where the distillate is collected.

Heat a distillation flask with the solution together with porcelain chips until it boils.

Pure solvent is collected in the beaker.

Fractional Distillation

Place a distillation flask under a bunsen burner and connect it to a fractional column. The fractional column is connected to a condenser.

Cold running water is allowed to enter from the bottom condenser and leave from the top.

Allow the condenser to slope downwards towards a beaker where the distillate is collected.

Heat a distillation flask with the mixture together with porcelain chips until it boils.

The miscible liquid with a lower boiling point is collected.

Separating funnel Pour the mixture into the separating funnel. Support the separating funnel using a retort

stand and place the beaker below the funnel. Allow the liquids to separate completely. The

denser liquid will fall to the bottom. Open the tap of the funnel to allow the bottom

layer to drain into the beaker. Close the tap when the liquid is fully drained. Place another beaker below the funnel to

collect a little of the top layer liquid so that the liquids are fully separated.

Sublimation

Place the mixture in an evaporating dish.

Position the dish under a bunsen burner.

Place an inverted funnel just above the dish.

The substance with high melting point would

be left on the dish.

The other substance will vapourise and

solidify when it lands on the surface of the

funnel.

Magnetic attraction

Place the mixture of magnetic and non-

magnetic objects in a dish.

Place a magnet directly above the dish.

Magnetic objects will be attracted to the

magnet while non-magnetic objects will be left

on the dish.

Separation method Common uses

Chromatography • Identify coloured substances used food products

• Identify if foods contain banned dyes

Filtration • Separating sand from water

• Human nose traps dust and allows oxygen to pass

Crystallisation • Separating salt from salt water

Simple Distillation • Separating water from salt water in desalination

Separation method Common uses

Fractional Distillation • Separate petrol, kerosene and diesel from petroleum

• Obtain nitrogen, argon and oxygen from air

Separating Funnel • Separate oil and water

Sublimation • Separate iodine from sand

Magnetic Attraction • Recycling magnetic materials by separating them

from domestic waste