BK'S LAW OF PREPARATION

1).  ) Law of conservation of mass : (Lavoisier and Landolt) . Matter is neither created nor destroyed in the course of chemical reaction though it may change from one form to other .   The total mass of materials after a chemical reaction is same as the total mass before reaction.             (2) Law of constant or definite proportion : Proust A pure chemical compound always contains the same elements combined together in the fixed ratio of their weights whatever its methods of preparation may be.            (3) Law of multiple proportion : Dalton and Berzelius When two elements A and B combine to form more than one chemical compounds then different weights of A, which combine with a fixed weight of B, are in proportion of simple whole numbers.                    (4) Law of equivalent proportion or law of reciprocal proportion : Ritcher The weights of the two or more elements which separately react with same weight of a third element are also the weights of t