Methods of Separating

Mixtures

What is a mixture?

When two or more materials or

substances are mixed together

but do not chemically

combine.

This means they retain their

original properties.

This means they can be

separated by physical means.

What are the different ways of

separating mixtures?

1. Magnetism

2. Filtration

3. Centrifuging

4. Decanting

5. Extraction and evaporation

6. Chromatography

7. Distillation

8. Crystallization

1- MAGNETISM

If one component of the mixture has magnetic

properties, you could use a magnet to separate

the mixture. Iron, nickel, and cobalt are all

materials that are magnetic.

Not all metals are magnetic: gold, silver, and

aluminum are examples of metals that are not

magnetic.

Magnetism examples

2- FILTRATION

Used when separating a solid substance from a fluid

(a liquid or a gas) by passing a mixture through a

porous material such as a type of filter.

Works by letting the fluid pass through but not the

solid.

Examples of filters: coffee filter, cloth, oil filter, even

sand!

Filtration is used to separate an insoluble solid from a

liquid.

Insoluble solid

trapped in

filter paper

Funnel with

filter paper

2- FILTRATION

Mixture of

solid and

liquidStirring

rod

Filtrate (liquid

component

of the mixture)

Filter paper

traps solid

Funnel

Filtration examplesUsing a coffee filter to separate

the coffee flavor from the coffee

beans.

Spin sample very rapidly:

denser materials go to

bottom (outside)

To use this method,

materials need to have

different density

Example: Separate blood

into serum and plasma

◦ Serum (clear)

◦ Plasma (contains red blood

cells ‘RBCs’)

Check for anemia (lack of iron)

Blood

RBC’s

Serum

A B C

AFTER

Before

3- CENTRIFUGING

Centrifugation examples

Go to the video

Go to the animation

4- DECANTING

Immiscible liquids, such as oil and water can

be separated by using a separating funnel.

The mixture is put into a separating funnel,

shaken and allowed to settle.

The oil and water from two separate layer. The

liquid with higher density, in this case water

forms the lower layer.

Remove the stopper and open the tap after

standing. The water runs out through the tap.

The oil remains in the funnel and can be run out

into another beaker

Decanting examples

Separating funnel

6- CHROMATOGRAPHY

A series of techniques used to separate a complex

mixture of substances

The mixture is dissolved in a fluid called the mobile

phase, which carries it through a structure holding

another material called the stationary phase. The various

constituents of the mixture travel at different speeds,

causing them to separate.

6- CHROMATOGRAPHY

There are many different types of chromatography methods

one of which is PAPER CHROMATOGRAPHY

This is good for separating, for example, dissolved substances

that have different colours, such as inks and plant dyes.

It works because some of the substances dissolve in the liquid

better than others, so they travel further up the paper.

Separation occurs because various components travel at

different rates on the stationary phase (chromatography paper)

Components with strongest attraction for paper travel the

slowest

6- CHROMATOGRAPHY

We often used chromatography to identify the substances

in a mixture. It is commonly used in hospitals. It helps

doctors to find out whether the patient has diabetes, if

paper chromatography might find out whether sugar is

present in the patient's urine.

Go to the video

7- DISTILLATION

This is good for separating a liquid from

a solution. Can be used to separate liquid

from liquid (alcohol from water) or solids

from liquids (water from salt)

This method works because the

substances that we are separating have

different boiling points.

For example, water can be separated from salty water by simple

distillation. Water evaporates from the solution, but is then cooled

and condensed into a separate container. The salt does not

evaporate and so it stays behind.

7- DISTILLATION

liquid with a solid

dissolved in it

thermometer

condenser

tube

distilling

flask

pure

liquid

receiving

flaskhose connected to

cold water faucet

Distillation examples

Distillation examples

Go to the video

Go to animation

Go to video 2

8- CRYSTALLIZATION

Separation technique that results in the

formation of pure solid particles from a solution

containing the dissolved substance

As the solvent evaporates, the dissolved

substance comes out of solution and collects

as crystals

Remember that it is the water (or solvent) that

evaporates away, not the solution

Produces highly pure solids

Rocky candy is an example of this

Crystallization examples

Go to the video