Amount of substance

Amount of substance
Amount of substance
	Approximately 1 mol amount of substance based on 12 grams of carbon-12
Common symbols	n
SI unit	mol
Dimension

In chemistry, the amount of substance (symbol $n$ ) in a given sample of matter is defined as a ratio ( $n = N / N A$ ) between the number of elementary entities ( $N$ ) and the Avogadro constant ( $N A$ ). The entities are usually molecules, atoms, ions, or ion pairs of a specified kind. The particular substance sampled may be specified using a subscript, e.g., the amount of sodium chloride (NaCl) would be denoted as $n NaCl$ . The unit of amount of substance in the International System of Units is the mole (symbol: mol), a base unit.^[1] Since 2019, the value of the Avogadro constant $N A$ is defined to be exactly 6.02214076×10²³ mol⁻¹. 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 International System of Units (PDF) (9th ed.), International Bureau of Weights and Measures, Dec 2022, ISBN 978-92-822-2272-0 p. 134

[bipm9th-1] The International System of Units (PDF) (9th ed.), International Bureau of Weights and Measures, Dec 2022, ISBN 978-92-822-2272-0 p. 134

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