Laws of Chemical Combination

Law of Conservation of Mass

This law was proposed by Antoine Lavoisier in the year 1789. After conducting several experiments, he observed that in all physical and chemical changes, there is no net change in the mass during the process. Thus he reached to the conclusion that matter can neither be created nor be destroyed.

Law of Definite Proportions

This law was given by the French chemist, Joseph Proust. He stated that a given compound always contains exactly the same proportion of elements by weight. After working with two samples of natural and synthetic cupric carbonate, he realised that the composition of elements present in it was same for both the samples. Thus, he concluded that a given compound always contained the same elements in a fixed proportion by mass.

Law of Multiple Proportions

This law was given by John Dalton in the year 1803. According to this law, if two elements combine to form two or more compounds, the masses of one element that combines with a fixed mass of the other element are in the ratio of small whole numbers.

For example, in the compounds Carbon Monoxide (CO) and Carbon Dioxide (CO2), the ratio of the masses of Oxygen is 1:2.