Is Matter Around us Pure?

PURE SUBSTANCES

• A pure substance is one which is made up of only one kind of particles.
• A pure substance is one which is made up of only one kind of atoms or molecules.
• All the elements and compounds are pure substances because they contain only one kind of particles.
• The elements like hydrogen, oxygen, nitrogen, chlorine.
• All the compounds such as water (including ice and steam), carbon dioxide, sodium chloride, sugar, copper sulphate, alum.
• A pure substance cannot be separated into other kinds of matter by any physical process.
• A pure substance has a fixed composition as well as a fixed melting point and boiling point.

IMPURE SUBSTANCES: MIXTURES

• A mixture is the one which contains two or more different kinds of particles (atoms or molecules).
• A mixture is a substance which consists of two or more elements or compounds neither loses its individuality nor is chemically combined together.
• All the mixtures are impure substances because they contain more than one kind of elements and compounds.
• The following are some examples of mixtures:
  • Seawater is a mixture of various salt and water.
  • Crude oil is a mixture of organic compounds (mainly hydrocarbons)
  • Gunpowder is a mixture of sulfur, potassium nitrate and carbon.
  • Ink is a mixture of coloured dyes.
  • Air is a mixture of various gases like oxygen, carbon dioxide, argon, neon, etc.
  • Some other examples of the mixtures are: salt solution, sugar solution, milk, sea-water, air, sugarcane juice.

General properties of mixtures:

Mixtures comprise two or more substances which are not chemically combined with each other. The properties of mixtures are as follows:

• The components can be separated easily.
• The proportion of the components is variable.
• The components of a mixture each keep their original properties.