Is Matter Around Us Pure

Most of the substances around us are not pure substances. Pure ghee or pure milk is not pure at all, from the perspective of science.

Matters can be classified into two types: Pure substances and Impure substances.

Matter
- Pure Substances
  - Element
  - Compound
- Impure Substances
  - Mixture
    - Homogeneous Mixture
      - Solution
    - Heterogeneous Mixture
      - Suspension
      - Colloid

Pure Substance

A substance made up only one kind of particle is called a pure substance. Elements and compounds are pure substances. Every particle of a lump of gold is the elment gold. Similarly, every particle of common salt is the compound sodium chloride

Impure Substance

A substance made up of more than one kind of particles is called an impure substance. There are different elements and/or compounds in an impure substance. For example: the so called pure ghee is composed of many compounds. Similarly, wood and paper are composed of different kinds of particles.

Mixture

An impure substance is also called mixture. In a mixture, components do not combine chemically or through any chemical change. In a mixture, components do not lose their properties.

Mixtures are of two types on the basis of their composition: Homogeneous mixture and Heterogeneous mixture.

Homogeneous Mixture

Mixtures which have uniform composition throughout are called Homogeneous Mixture. For example – mixture of salt and water, mixture of sugar and water, air, lemonade, soda water, etc.

Mixture of salt in water is an example of homogeneous mixture. In this mixture, the boundary of salt and water cannot be differentiated. When a ray of light is passed through the mixture of salt and water, the path of light is not seen.

Properties of Homogeneous Mixture:

All solutions are examples of homogeneous mixture.
The particles of a homogeneous mixture are less the one nanometer in size.
A homogenous mixture does not show Tyndall effect.
The boundaries of particles cannot be differentiated.
The constituent particles of homogenous mixture cannot be separated using centrifugation or decantation.
Alloys are the examples of solution.

Quiz

See Answer

1: (d) Copper, 2: (c) Brass, 3: (a) One, 4: (b) Two, 5: (c) Milk

Heterogeneous Mixture

Mixtures which do not have uniform composition throughout are called Heterogeneous Mixture. For example – mixture of soil and sand, mixture of sulphur and iron fillings, mixture of oil and water etc. The boundaries of constituent particles of a homogeneous mixture can be identified easily; as a homogeneous mixture has two or more distinct phases.

Properties of Heterogeneous Mixture:

Most of the mixtures are heterogeneous except solutions and alloys.
The constituent particles are present uniformly in a heterogeneous mixture.
The components of a heterogeneous mixture can be identified easily.
Generally, two or more phases are present in a heterogeneous mixture.
Particles of a heterogeneous mixture are sized between one nanometer and one micrometer or more.
Heterogeneous mixtures show Tyndall effect.