Chemical Equations And Laws

Law of definite proportions:

This law was given by Proust in 1799 and stated as:
Irrespective of the method of preparation of a compound from two or more elements, they combine in a fixed ratio of their weights.
Example:
1) Formation of water:
(i)By passing electric discharge through a mixture of hydrogen and oxygen.
(ii)When an acid and a base react, salt and water are forme when water obtained by the above methods is observed, hydrogen and oxygen are combined in the ratio of 2 : 16 or 1:8.

2) Formation of carbondioxide:
(i)By the decomposition of metallic carbonates
(ii)By burning carbon and oxygen
(iii)By reaction of metallic carbonates with acids
(iv)By heating sodium bicarbonate

when the sample of CO₂ is taken by any of the above methods, it is observed that carbon and oxygen are always combined in the ratio of 12:32 (or) 3:8.