Explain the Law of Definite Proportions

The law of definite proportions states that all pure samples of a particular chemical compound contain similar elements combined in the same proportion by mass.

The second law of chemical combination which is supported by the Atomic theory was proposed by Proust (1755-1826). Known as the Law of Definite Proportions or Constant Composition ,it is based on the fact that when elements combine to form a given compound , they do so in fixed proportions by mass so that all pure samples of that compound are identical in composition by mass.

Consider water for example . Chemical analyses showed that as long as it is pure, its composition is always in the ratio of one mole of oxygen molecules (i.e 32 g) to two moles of hydrogen molecules (i.e 4g) , irrespective of whether the water comes from the river , sea, rain ,wine ,saliva  or any other source .

Explanation:

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