Stir sugar into one glass of water. Stir sand into another.
Both are mixtures — but they do not look the same at all.
What exactly is the difference?
How many types of mixtures are there?
Types of mixtures
Mixtures
Two or more substances mixed
Homogeneous
Same composition everywhere
Example:
Sugar and water
Vinegar
Soda
Heterogeneous
Composition differs from place to place
Example:
Sand and water
Oil and water
Mixtures are of two types —
homogeneous
and
heterogeneous
.
To tell them apart, we look at whether the mixture is the same all through.
What happens when we mix sugar in water?
Sugar dissolves fully and spreads through the whole of the water.
The
first sip is as sweet as the last sip
.
This means the sugar is spread
equally everywhere
.
So sugar and water make a
homogeneous mixture
.
Composition
means how much of each substance is present;
uniform
means the same at every place.
Definition
A
homogeneous mixture
is a mixture whose composition is the same throughout. It is also called a
solution
.
What happens when we mix sand in water?
Sand does not dissolve properly in water.
In some places there is more sand, in other places less.
The sand particles are easily seen, and they
settle with time
.
So sand and water make a
heterogeneous mixture
.
Definition
A
heterogeneous mixture
is a mixture whose composition is
not
the same throughout.
What is the difference between homogeneous and heterogeneous mixtures?
Point
Homogeneous mixture
Heterogeneous mixture
Definition
Composition is the same everywhere in the mixture
Composition is not the same everywhere in the mixture
Composition
Uniform — take it from the top or the bottom, it is the same
Non-uniform — something different at the top, something else at the bottom
Particles
Not visible
Easily visible, and they settle with time
Example
Sugar and water
Sand and water
Example
More homogeneous mixtures —
vinegar
, which is acetic acid in water, and
soda
and other aerated drinks, which are carbon dioxide in water. "Aerated" means a gas is dissolved in it.
Example
A solution always stays homogeneous. However well you stir sand and water, it never becomes homogeneous.
๐งช Activity 5.1 — Let us experiment
Your book gives Activity 5.1, in which three groups make three mixtures — salt in water, chalk powder in water, and milk in water — and shine a laser through each.
We will not do it here. We will take it up in
5.5, the Tyndall effect
, where its result actually makes sense.
๐ Summary - What we have learnt
Mixtures are of two types —
homogeneous
and
heterogeneous
.
A
homogeneous
mixture has uniform composition; sugar and water is the example.
A
heterogeneous
mixture has non-uniform composition; sand and water is the example.
Every homogeneous mixture is also called a
solution
.
Recap — Section 5.1 — How Can We Classify Mixtures?
โ Test Yourself
You stir chalk powder into water. Even after mixing well, is the composition the same throughout?
View Answer
Hide Answer
No — chalk powder does not dissolve, so it settles unevenly. That makes it a heterogeneous mixture, not a homogeneous one.
True or false — every solution is a homogeneous mixture.
View Answer
Hide Answer
True. "Solution" is just another name for a homogeneous mixture.
Name one homogeneous mixture other than sugar and water.
View Answer
Hide Answer
Vinegar (acetic acid in water) or an aerated drink like soda (carbon dioxide in water) — any homogeneous example works.
Important Definitions
Mixture
Two or more substances mixed together without any new substance being formed.
Homogeneous mixture
A mixture whose composition is the same throughout; also called a solution.
Heterogeneous mixture
A mixture whose composition is not the same throughout.
Questions at the End of the Chapter — Related to This Section
๐ NCERT Question 1 — Classifying mixtures as Hm or Ht
Classify a set of given mixtures as homogeneous (Hm) or heterogeneous (Ht).
CA Maninder Singh is a Chartered Accountant with 16+ years of practical experience and 20+ years of teaching experience. At Teachoo, he simplifies Accounts, Tax and GST with step-by-step examples so students can apply concepts confidently in exams and real life.
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