Amount of substance

Common card · No. 277386

In chemistry, the amount of substance (symbol n) in a given sample of matter is defined as a ratio (n = N/NA) between the number of elementary entities (N) and the Avogadro constant (NA). It is one of the seven base quantities of the International System of Units, SI. The unit of amount of substance in the SI is the mole (symbol: mol), a base unit. Since 2019, the mole has been defined such that the value of the Avogadro constant NA is exactly 6.02214076×1023 mol−1, defining a macroscopic unit convenient for use in laboratory-scale chemistry. The elementary entities are usually molecules, atoms, ions, or ion pairs of a specified kind. The particular substance sampled may be specified using a subscript or in parentheses, e.g., the amount of sodium chloride (NaCl) could be denoted as nNaCl or n(NaCl). Sometimes, the amount of substance is referred to as the chemical amount or, informally, as the "number of moles" in a given sample of matter. The latter term is deprecated by the IUPAC because...

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