Mole (mol)

How to read it

The BIPM’s SI Brochure defines the mole by that number, the fixed value of the Avogadro constant N_A, and gives the amount of substance itself the italic symbol n. OpenStax’s Chemistry 2e compares the mole to counting units like a pair, a dozen or a gross, and notes that one Latin meaning of the word “mole” is “large mass” or “bulk”. The symbol stays the same in the plural, 2 mol, as NIST’s Guide for the Use of the SI says of all unit symbols.

Also searched as: Avogadro constant, M molar, mol, mole symbol, mol in chemistry, mol unit.

M for molar

The concentration of a solution in moles per litre, mol/L, is often written M and read “molar”. The IUPAC Green Book accepts M, mM and µM, pronounced molar, millimolar and micromolar, though it advises against the older name molarity, which is easily confused with molality. NIST’s guide goes further and calls both molarity and the symbol M obsolete, asking for the amount-of-substance concentration in units such as mol/dm³ or mol/L instead.