List the pure and impure substances and list the basic componente
Answers
Answer: (a) A pure substance is either an element or compound. It contains the same kind of atoms or molecules and has a definite set of physical and chemical properties.
Example of pure substance is oxygen gas, made of oxygen molecules O
2
.
(b) A substance in which some other substances are also present in smaller or larger amounts is called an impure substance. Mixtures are impure substances.
An example of an impure substance is air. It is a mixture of several gases like oxygen gas, hydrogen gas, nitrogen gas, etc.
(a)
Pure substances -
1. Pure substances have definite composition and definite physical and chemical properties.
2. They are all homogeneous i.e. their composition is uniform throughout the bulk.
3. Examples: Elements and compounds.
Impure substances -
1. Impure substances are made up of two or more pure substances mixed together in any proportion.
2. They may be homogeneous or heterogeneous i.e. their composition is not uniform throughout the bulk.
3. They are all mixtures.
Examples: air, sea water, petroleum. a solution of sugar in water are all impure substances.
(b)
Homogeneous mixture - is a mixture where the components that make up the mixture are uniformly distributed throughout the mixture.
Example - air, sugar water, rain water.
Heterogeneous mixture - is a mixture, where the components of the mixture are not uniform or have localized reglos with different properties.
Example - Cereal In milk, vegetable soup.