Law of definite proportions

The Law of Definite Proportions is a scientific principle formulated by Joseph Louis Proust in 1799, which states that every chemical compound is composed of a fixed and constant proportion (by weight) of its constituent elements. This means that the weights of the elements in a chemical compound correspond to fixed ratios, as determined by the law.From: Basic Chemical Concepts and Tables [2019], Biographical Encyclopedia of Scientists [2019], Berthelot’s Pathway from Synthesis to Thermochemistry [2019]

Stoichiometry

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Published in Himadri Roy Ghatak, Reaction Engineering Principles, 2018

Roy Giratali Himadri

As noted in Chapter 1, a chemical reaction is the phenomenon that transforms one chemical species into another. The reaction will start with one or more types of chemical species. These are known as the reactants. As the reaction proceeds, the reactants will deplete in mass. In their place, one or more types of new chemical species will be formed. These are known as products. The mass of the products go on increasing with the progress of the reaction. Stoichiometry is the discipline of science that allows us to calculate the mass of any chemical species (reactant or product) in the reacting system in relation to the other species present (IUPAC Gold Book, 2014). It is founded in two fundamental laws of chemistry, namely the Law of Definite Proportions and the Law of Multiple Proportions, along with the Law of Conservation of Mass.

Berthelot’s Pathway from Synthesis to Thermochemistry

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Journal Information

Published in Ambix, 2019

Vangelis Antzoulatos

Unfortunately for Berthollet, a new conception of chemical combination appeared at the same time as the publication of the Essai. In 1794, then more explicitly in 1799, Joseph Louis Proust (1754–1826) enunciated the law of definite proportions, according to which the weights of the elements in chemical compounds correspond to fixed ratios.35 This idea soon found significant support with the atomic theory of John Dalton (1766–1844), and his law of multiple proportions. In a short time, most chemists abandoned the Bertholletian corpuscularian ontology, and rejected the idea of equilibrium in favour of a return to complete and unequivocal action, the only mode seemingly able to explain multiple proportions.

Law of definite proportions

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Stoichiometry

Berthelot’s Pathway from Synthesis to Thermochemistry