Law of multiple proportions

In chemistry, the law of multiple proportions states that in compounds which contain two particular chemical elements, the amount of Element A per measure of Element B will differ across these compounds by ratios of small whole numbers. For instance, the ratio of the <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a> content in <a href="/facts/Methane/kBHneYnh">methane</a> (CH4) and <a href="/facts/Ethane/BGCzc6yh">ethane</a> (C2H6) per measure of <a href="/facts/Carbon/ukrgQexo">carbon</a> is 4:3. This law is also known as <a href="/facts/Dalton%27s_Law/kWQDom5X">Dalton's Law</a>, named after <a href="/facts/John_Dalton/oS8grQR4">John Dalton</a>, the chemist who first expressed it. The discovery of this pattern led Dalton to develop the modern theory of <a href="/facts/Atoms/FoQ4kGN5">atoms</a>, as it suggested that the elements combine with each other in multiples of a basic quantity. Along with the <a href="/facts/Law_of_definite_proportions/spaNgzcc">law of definite proportions</a>, the law of multiple proportions forms the basis of <a href="/facts/Stoichiometry/I5p9cJzV">stoichiometry</a>.
The law of multiple proportions often does not apply when comparing very large molecules. For example, if one tried to demonstrate it using the <a href="/facts/Hydrocarbon/Dcg95Ju5">hydrocarbons</a> <a href="/facts/Decane/KPn6cJbz">decane</a> (C10H22) and <a href="/facts/Undecane/4TxojILx">undecane</a> (C11H24), one would find that 100 grams of carbon could react with 18.46 grams of hydrogen to produce decane or with 18.31 grams of hydrogen to produce undecane, for a ratio of hydrogen masses of 121:120, which is hardly a ratio of "small" whole numbers.

Law of multiple proportions open-in-new

Law of multiple proportions