Avogadro constant of molecules in one gram-molecule of oxygen (exactly of oxygen, according to the definitions of the period), and this term is still widely used, especially in introductory works. The change in name to "Avogadro constant" ("N") came with the introduction of the mole as a base unit in the International System of Units (SI) in 1971, which regarded amount of substance as an independent dimension of measurement. With this recognition, the Avogadro constant was no longer a pure number, but had a unit of measurement, the reciprocal mole (mol). While it is rare to use units of amount of substance
Entropy entropy, have dimensions of energy divided by temperature, which has a unit of joules per kelvin (J K) in the International System of Units (or kg m s K in terms of base units). The entropy of a substance is usually given as an intensive property—either entropy per unit mass (SI unit: J K kg) or entropy per unit amount of substance (SI unit: J K mol). The French mathematician Lazare Carnot proposed in his 1803 paper "Fundamental Principles of Equilibrium and Movement" that in any machine the accelerations and shocks of the moving parts represent losses of "moment of