law of multiple proportions

In chemistry, the law of multiple proportions is one of the most basic laws of stoichiometry. It is related to the law of definite proportions. It is sometimes called Dalton's Law after its discoverer, the English chemist John Dalton, though this usually refers to his law of partial pressures.If two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers. Another way to say this is: A law proposed by Dalton which states that when elements combine, they do so in the ratio of small whole numbers. For example carbon and oxygen react to form CO or CO2, but not CO1.8.
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Noun
1. (chemistry) law stating that when two elements can combine to form more than one compound the amounts of one of them that combines with a fixed amount of the other will exhibit a simple multiple relation
(synonym) Dalton's law
(hypernym) law, law of nature
(classification) chemistry, chemical science

When one element can combine with another to form more than one compound, the mass ratios of the elements in the compounds are simple whole-number ratios of each other. For example, in CO and in CO2, the oxygen-to-carbon ratios are 16:12 and 32:12, respectively. Note that the second ratio is exactly twice the first, because there are exactly twice as many oxygens in CO2 per carbon as there are in CO.