What is the law of Multiple Proportions. Explain giving examples

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conceptsofchemistry

#1

The Law of Multiple Proportions states:
“When two elements combine to form two or more chemical compounds, the ratio between different weights of one of the elements which combine with a fixed weight of the other is always simple.” Examples:

  1. Compound of Carbon and Oxygen : C and O combine to form two compounds CO and C${{O}_{2}}$.
    In CO, 12 parts by wt. of C combine with 16 parts by wt. of O.
    In CO2,12 parts by wt. of C combine with 32 parts by wt. of O.
    If the weight of C is fixed at 12 parts of wt. then the ratio in the weights of oxgyen which combine with the fixed wt. of C (= 12) is 16 : 32 or 1:2.
    Thus the weights of oxygen bear a simple ratio of 1 : 2 to each other. 2
  2. Compounds of Sulphur (S) and oxygen (O):
    S forms two oxides with O, viz. S${{O}{2}}$ and S${{O}{3}}$
    In S${{O}{2}}$,32 parts by wt. of S combine with 32 parts by wt. of O.
    In S${{O}
    {3}}$, 32 parts by wt. of S combine with 48 parts by wt. of O.
    If the wt. of S is fixed at 32 parts, then the ratio in the weights of oxygen which combine with the fixed wt.
    of S is 32:48 or 2 : 3.
    Thus the weights of oxygen bear a simple ratio of 2 : 3 to each other