Good Science Victorian Curriculum Year 7

CHAPTER 5: MIXTURES
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Mixtures are made up of different particles
A mixture is a substance where not all of the particles are the same.
Mixtures are usually made up of more than one pure substance.
Think about a cup of instant coffee. The coffee
contains coffee powder, some boiled
water from the kettle and perhaps
some milk or sugar. This means
that coffee is a mixture of
all of these substances.
A microscope would
show that a cup of coffee
contains many different
types of particles.
Another example of a
mixture is the air that we
breathe. Air contains mostly
nitrogen, oxygen, argon and
carbon dioxide particles. When we
use the word ‘air’, we are referring to Figure 5.2 Pizza is an example
the mixture of all of these gases.
of a delicious mixture because
it is made up of a variety of
different substances.
Give two examples of mixtures.
Different mixtures require different
separation techniques
It’s very easy to make coffee, but can we do it in reverse? Can we take
a cup of coffee and separate it out into water, coffee powder, sugar
and milk? In fact, we can! It sounds impossible, but by using the correct
scientific techniques and equipment, we are able to separate all sorts
of mixtures into their parts.
However, it is very important that we use the correct techniques in the
correct order. The procedure used to separate coffee from water would
be very different from the procedure used to separate nitrogen from
oxygen.
Separation of mixtures is very important in our day-to-day lives.
There are very few pure substances found in nature, so we need to
separate mixtures to extract the pure substances that we want to use.
For example, in order to use aluminium to make a can of soft drink,
we need to separate the aluminium from the ore that it is found in.
Without the correct separation techniques, we wouldn’t be able to use
this aluminum, or many other pure substances that we use every day.
What is aluminium mixed with in nature?
CHECKPOINT 5.1
1 How are the particles in a
pure substance and a mixture
different from each other?
2 Draw a diagram showing the
particles in:
a pure water
b air.
3 Make a list of mixtures you
have come into contact with
today.
4 In your own words, explain why
it is important to be able to
separate mixtures.
5 Which of the following are
mixtures, and which are pure
substances?
sugar, tea, mud, copper,
diamond, soup, sea water
6 Out of all of the substances in
question 5, list the ones that
you would be able to separate
into their components.
RESEARCH
7 There are many different types
of mixtures. Use the internet
to find out what is meant
by a heterogenous mixture,
a homogenous mixture,
a colloid and a suspension.
Give an example of each.
SUCCESS CRITERIA
I can describe the difference
between a mixture and a
pure substance in my own
words.
I can give some examples of
separation techniques used
in everyday life.
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