n.
or mol
Standard unit for measuring everyday quantities of such minute entities as atoms or molecule s.
For any substance, the number of atoms or molecules in a mole is Avogadro's number (6.02 00D7; 10 23 ) of particles. Defined exactly, it is the amount of pure substance containing the same number of chemical units that there are in exactly 12 g of carbon -12. For each substance, a mole is its atomic weight , molecular weight , or formula weight in gram s. The number of moles of a solute in a litre of solution is its molarity ( M ); the number of moles of solute in 1,000 g of solvent is its molality ( m ). The two measures differ slightly and have different uses. See also stoichiometry .