Law of Multiple Proportions.

LAW OF MULTIPLE PROPORTIONS:

This law was proposed by John Dalton (1763-1844) in the year 1803. He was not a good experimenter (perhaps because he was colorblind), but he skillfully used the results of others in formulating this law.

STATEMENT:

“When two elements combine together to form more than one compound, the different weight of one of these elements which combines with the definite weight of the other elemts are in simple ratio.”

EXAMPLES:

Compounds of “H” and “O”

S. No	Compound	Formula	Wt of O	Wt of H	Ratio
1	Water	H2O	16	2	2:16
2	Hydrogen peroxide	H2O2	32	2	2:32

Compounds of “C” and “O”

The oxygen-to-carbon mass ratio in carbon-di-oxide is twice that found in carbon monoxide.

S. No	Compound	Formula	Wt of C	Wt of O	Ratio
1	Carbon monoxide	CO	12	16	12:16
2	Carbon-di-oxide	CO2	12	32	12:32

Compounds of “N” and “O”

S. No	Compound	Formula	Wt of N	Wt of O	Ratio
1	Nitrous oxide	N2O	28	16	28:16
2	Nitric oxide	N2O2=NO	28	32	28:32
3	Nitrogen trioxide	N2O3	28	48	28:48
4	Nitrogen tetra oxide	N2O4=NO2	28	64	28:64
5	Nitrogen pent oxide	N2O5	28	80	28:80

CONCLUSION:

It is clear from all these examples that the law of multiple proportions is verified.