Page 48 - ICSE Chemistry 8

MIXTURES

A mixture consists of two or more pure substances such as elements, compounds or both that retain
their individual proper es. Air is a mixture of diff erent gases such as nitrogen, oxygen, carbon dioxide and
other gases. A combina on of sugar and water forms a solu on.

Characteristics of Mixtures

• A mixture has no defi nite composi on. The cons tuents of a mixture are not present in a fi xed
ra o.

• The cons tuents of a mixture can be separated by simple physical methods. This is because there
is no chemical reac on taking place between the cons tuents of a mixture and hence the forces
of a rac on holding the cons tuents are weak.
• The original proper es of cons tuents of a mixture are retained.

• A mixture has no fi xed mel ng and boiling points.
• A mixture has no fi xed physical and chemical proper es.

• There is no energy absorbed or released during the forma on of a mixture.
Classification of Mixtures Thinking Fountain
Give some examples of homogeneous
Mixtures can be classifi ed as homogeneous or heterogeneous.
and heterogeneous mixtures from your
Homogeneous Mixtures surroundings.

A mixture in which the cons tuents are uniformly distributed throughout is called a homogeneous mixture.
A salt solu on, a glucose solu on, and an alloy of iron and carbon are some examples of homogeneous
mixtures. The cons tuents of these mixtures are not clearly visible and cannot be iden fi ed individually.

Heterogeneous Mixtures

A mixture in which the cons tuents are distributed non-uniformly is called a heterogeneous mixture.
A mixture of iron fi lings and sulphur powder, a mixture of oil and water and a mixture of chalk powder
in water are some examples of heterogeneous mixtures. The cons tuents of these mixtures are clearly
visible and can be iden fi ed individually.

Heterogenous mixtures are found in the form of suspensions or emulsions.
• Suspension: A type of mixture in which a component is not dissolved completely into another
component is called a suspension. The undissolved par cles remain unequally distributed
throughout the mixture and se le down when the mixture is le undisturbed for some me. Chalk
in water and dust in air are examples of suspensions.

• Emulsion: A type of mixture in which par cles of one liquid are not dissolved but dispersed in
another liquid is called an emulsion. A type of mixture consis ng of two or more immiscible liquids
is also an emulsion. An emulsion is formed on mixing oil and water.
Formation of Mixtures

Diff erent mixtures can be formed on combining diff erent states of ma er. The following table shows
diff erent types of mixtures.

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