what are difference between pure and impure subtances?

 PURE SUBSTANCE : A substance having one types of atoms or molecules  is called a pure substance.

A pure substance is either an element like carbon and hydrogen or a compound like salt and sugar .

EXAMPLES: oxygen, hydrogen ,  carbon , gold , silver, etc.

all chemical compounds such as water sait, sugar, etc.

PROPERTIES OF A PURE SUBSTANCE:

* It cannot be separated into two or more substances by physical or mechanical manner.

*It is homogeneous.It means that it has uniform compositions throughout the whole sample.

*It has definite chemical composition.

*It has definite properties like melting point or boiling point.

IMPURE SUBSTANCES:

Impure substances are commonly called mixtures.

In other words, a mixture or an impure substance is made up of two or more substances.

The difference substances present in a mixture are called its components or constituents.

mixtures are the substances held together by physical forces known as intermolecular forces.

EXAMPLE:sea water is a mixture which contains large number of salts and other impurities in it.

milk is a  mixture of water, cream, and proteins of many types.

air is a homogenous mixture whose components can not be seen by naked eyes.

CLASSIFICATION OF MIXTURES:

1. Mixtures having a uniform composition throughout the mixture are called homogenous mixture.

e.g. soft drink, milk

2. Mixture lacking a uniform composition throughout the mixture are called heterogenous mixture.

e.g. heap of wheat