The mole, symbol mol, is the SI unit of 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 called the “Avogadro number”.
The amount of substance, symbol n, of a system is a measure of the number of specified elementary entities. An elementary entity may be an atom, a molecule, an ion, an electron, any other particle or specified group of particles.
The measurements traceability is done to national and international standards, guaranteed through the use of traceable equipment to the SI units and by the adoption of preparation and certification of gas mixtures methods in agreement with the applicable international standards.
The accuracy of the measurements made is proven through the participation in projects and in international comparisons, and it is demonstrated by the acceptance and inclusion in the Capacities of Measurement and Calibration (CMC) BIPM database and also with the international equivalence of measurements through the Mutual Recognition Arrangement (CIPM-MRA), for IPQ gas mixtures.
External document:
Mise en pratique for the definition of the mole in the SI