The mole is the SI base unit for the amount of a substance. It is currently defined by comparison with the number of atoms in 12 g of Carbon-12.
Moles are measures of the amounts of substances. Accurate molar values are vital for effectively administering medicines and for all chemistry research. It is important in calculating the yield of industrial chemical reactions to know the amount of substances based on the number of atoms or molecules.
Amadeo Avogadro first proposed that the volume of a gas at a given temperature and pressure is proportional to the number of atoms, regardless of the gas.
As a result of his contributions to molecular theory, the number of atoms in 12 g of Carbon-12, used to define the mole, was named in his honour.
In 2019, the mole is expected to be redefined using Avogrado's number – 6.02×1023.