Amount of substance has the unit mole.
- The mole, denoted by the symbol mol, is the SI unit of the amount of substance.
- One mole contains exactly 6.022 140 76 x 1023 elementary entities. This number is the fixed numerical value of the Avogadro constant, NA, when expressed in the unit mol–1 and is known as the Avogadro number. The value of Avogadro’s number is fixed and the value is NA = 6.022 x 1023.