GRADE 7 SCIENCE

Separating SolutionsPage 277

REMEMBER...

Something is a MIXTURE if it contains

two (or more) substances that are not

chemically joined together.

The substances in a mixture can often be

easily separated from one another.

A PURE substance only contains one

material and so cannot be separated in

any way (unless a chemical reaction takes

place).

DIFFERENT SEPARATION TECHNIQUES

Are there mixtures that can

not be separated?

Are there mixtures in and

around your home that you

do not want to separate?

Why can one mixture be

separated with a filter while

another can not?

Because of Particle size and the

type of mixture!

DIFFERENT METHODS TO SEPARATE MIXTURES

9 –1 A P. 279

How you would separate

the following mixtures…

Salt water

Muddy water

Nuts and bolts

Salt water

Evaporation

Used as a separation method when parts of the mixture have

different boiling points.

When salty water is warmed the water evaporates leaving

behind crystals of salt.

Muddy water

Filtration

Used when there is a liquid and solid parts to the mixture.

Nuts and bolts

Mechanical sorting.

- Floating

- Magnetism (the magnet sticks to the iron but not to the sand)

- Using your hands!http://www.youtube.com/wa

tch?v=bHP1HQHAQrw

SEPARATION OF MIXTURES OCCUR IN MANY

BRANCHES OF SCIENCE:

Food science

Tea bags

Chemistry

Water softeners

Engineering

Oil and gas

filters

Life science

Bogs

THERE ARE COMMON SEPARATION TECHNIQUES

USED TO SEPARATE THE COMPONENTS OF A

VARIETY OF MIXTURES.

Straining spaghetti

in a colander.

Skimming fat off

soup.

Drying clothes (water

from fabric)

Window screens (air

in bugs out)

Making coffee using

ground coffee beans

SEPARATION TECHNIQUES IN THE

HOME:

Mixtures that exist in the

home:

dust from carpet

water from clothes

rocks from topsoil

cigarette smoke from air

__________________________

CHOOSE THE APPROPRIATE SEPARATION

TECHNIQUE

Technique Solvent Solute Process

Colander water Spaghetti Filtration

Clothes dryer Water Clothes Evaporation

Window screen Air Bugs Filtration

Coffee percolators Water Coffee beans Filtration

Vacuum cleaners Carpet Dust Filtration

Skimming fat from soup Soup Fat Floatation

Refining oil Water Oil Distillation

Toxic screen Blood Alcohol Chromatography

Separating Sand Iron fillings Magnetism

Drinking apparatus Water Salt Distillation

SEPARATING MIXTURES

AND SOLUTIONS

Separating heterogeneous mixtures

1. Mechanical sorting

a) Magnetism

b) Floatation

2. Filtration

Separating homogeneous mixtures

1. Evaporation

2. Distillation

Separating a solution by paper chromatography

SEPARATING HETEROGENEOUS MIXTURES

Heterogeneous mixture: a combination of

two or more different types of matter that

retain their own properties that can be

detected quite easily.

1. Mechanical sorting

Floatation

Magnetism

2. Filtration

SEPARATING

HETEROGENEOUS MIXTURES

1. Mechanical Sorting:

Used to separate the parts

of a mixture based on

properties such as particle

size.

Ex: floatation & magnetism

floatationmagnetism

FILTRATION:A common way to

separate solid particles

from a mixture

The filters can have

holes of varying sizes…

small to microscopic.

EXAMPLES OF FILTRATION

Wood chips and

water

Styrofoam

particles and

water

Sand and water

Cornflakes and

water/or milk

Water and stones

(pebbles)

Coffee filter Oil filter

Furnace filter

Colander

SEPARATING HOMOGENEOUS MIXTURESP.282

Homogeneous mixture: a

combination of two or more

different types of matter that

appear to be the same throughout

the mixture and have the same

properties.

1. Evaporation

2. Distillation

EVAPORATION:

Change of state from a liquid

to a gas.

Liquid (solvent) evaporates

to recover a solid solute from

a solution.

Salt (solute) and water (solvent)

Sugar (solute)and water (solvent)

DISTILLATION:

Is a method that you can use to

separate and recover a single solute

and a single solvent from a solution.

Uses the property of the boiling point

to separate two components of a

solution (solvent and solute)

Uses two changes of state: evaporation

and condensation (collect solvent) Example: (1)alcohol from water &(2) salt from water

DISTILLATION

The solution is heated until it reaches the

solvent boiling point.

The solvent changes state to become a gas and

evaporates .

The gas is then collected in the condenser, and

cooled.

While in the condenser, the gas condenses and

turns back into a liquid.

The condensation (liquid solvent) is collected

into the receiving flask.

The solute remains at the bottom of the flask

and is not evaporated.

Condensation

Evaporation

http://www.youtu

be.com/watch?v

=xxNfJLMNS4E

http://www.youtube.com/watch?v=zW3C1RRulmg

TWO TYPES OF DISTILLATION

1. SIMPLE DISTILLATION

Simple distillation generally

separates a single solute from

its solvent.

2. FRACTIONAL DISTILLATION

Fractional

distillation

separates a

mixture of

liquids based

on their

varying boiling

points.

http://www.youtube.com/watch?v

=PYMWUz7TC3A

SEPARATING A SOLUTION BY

PAPER CHROMATOGRAPHY

Used to separate the colored substances in a mixture

such as ink.

Used to separate the solvents in a mixture.

How it works:

The speed of a

dissolved substance

is carried by a

solvent through a

material such as

filter paper, that

absorbs the solutes.