Stephen Aldehyde Synthesis

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 these elements which react with each other or in simple multiple of them.

           

(5) Gay-Lussac’s law :

 Gay–Lussac 

 When gases combine, they do so in volumes, which bear a simple ratio to each other and also to the product formed provided all gases are measured under similar conditions.