Page 1 - 3.Lesson Notes_Pure and Impure Substances

SAI International School
Subject-Chemistry
Ch-Is Matter around us pure?

Topic-Pure and Impure substances
LESSON NOTE

Pure substances: In pure substance all the constituent particles are same in their
chemical nature or properties. A pure substance consists of only one type of
particles.

A substance is a kind of matter that cannot be separated into other kinds of matter
by any physical process and its composition is same throughout.

Characteristics of pure substances:

• They are composed of same kind of particles
• They are homogeneous

• They cannot be separated into any other kinds of matter by physical

processes.
• They have fixed composition throughout.

• They have fixed properties throughout.

• They have fixed melting and boiling points
• Examples: Elements and compounds

Impure substances or mixtures: In impure substances all the constituent particles
are not same. The impure substances or mixtures consists of different types of
particles.

Characteristics of impure substances or mixtures:

• They are composed of different kind of particles
• They may be homogeneous or heterogeneous

• They can be separated into any other kinds of matter by physical processes.

• They do not have fixed composition throughout.
• They do not have fixed properties throughout.

• They do not have fixed melting and boiling points

• Examples: Mixtures