Pure Substances

Matter can be broadly classified into two major groups " Pure" and "Impure". In chemistry, a pure substance is the one which is made of only one type of constituent particles. On the basis of purity all matter can be classified into two types :- Pure substance and Mixture.

Pure Substance: 

A substance is called pure when it contains molecules of only one kind. Each particle of the substance has the same unique property. For example; distilled water is pure water as each drop of it contains nothing but water. In chemistry when we say a substance is pure, it means that the substance is made up of only one type of constituent particles. A pure substance consists of a single type of particles. In other words, a substance is a pure single form of matter.

A pure substance has a constant composition. Water, for example, is always 88.81% oxygen by weight. Pure substances also have constant chemical and physical properties. Foe eg:- Water freezes at exactly  and boils at exactly  at atmospheric pressure. This shows that composition  and properties of a pure substance are the same regardless of where it is found.