Pure Substance

Let us learn about "Pure Substance"

The distinctive features of pure substances are:

• A pure substance is composed of the same kind of particles e.g. hydrogen, oxygen, water, sodium chloride, etc.
• A pure substance is homogeneous, irrespective of its origin or method of preparation.
• A pure substance has definite properties, characteristic of itself.
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• A pure substance has the same composition throughout. For example, different samples of water, prepared by different methods, by different people at different places always consist of hydrogen and oxygen in the ratio 1:8 by mass and 2:1 by volume. If any sample has a different ratio of these elements, then it certainly is not water.
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Pure substances can be classified into elements and compounds. Lavoisier, a French chemist, was the first to do this on the basis of quantitative studies. He showed that when we heat mercuric oxide it changes into mercury and oxygen.

Mercuric oxide----------------> Mercury + Oxygen Mercuric oxide is a compound because it decomposes into simpler substances, whereas mercury and oxygen cannot be further decomposed into anything simpler as they are elements

In our next blog we shall learn about vsepr theory

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