1 Molar concentration 
The molar concentration of a substance B in a solution of the quotient of the number of moles of substance B and the volume of the solution Lg The corresponding SI unit is 1 mol / m³. Furthermore, mol/l,  mol/dm ³, mmol/l, mol/ml, kmol/m³ permitted. A solution with the molar concentration of 1 mol/l is also referred to as a 1 molar (abbreviated 1 M).

c _B = n _B / v _Lg

2 Equivalent concentration 
The equivalent concentration, also called norm, of a substance B in a solution is defined as the quotient of the Soffmenge the equivalent (the number of equivalents is given by the stoichiometric value z of a molecule) and the volume of the solution. Apply the same units as the molar concentration.
A solution of the equivalent concentration c _{Ä, B} of 1 mol / l is referred to as 1 Normal (short 1N).

c _{Ä, B} = n _{Ä, B} / v _Lg = c _B * z = (n _B * z) / v _Lg

3 Molality 
The molality of a substance B in a solution is defined as the quotient of the number of moles of substance B and the mass of the solvent Lm The resulting valid SI unit is 1 mol/kg.
A solution of molality _{m c, B} = 1 mol / kg is also designated as 1 molal.

c _{m, B} = n _B / m _Lm

4 Mass concentration 
The mass concentration of a substance B in a solution is defined as the ratio of the mass of the substance B and the volume of the solution.
The SI unit is 1 kg / m³. Furthermore, the following units are permitted: g / l, mg / ml, mg / l, g / cm ³, ug / ml. Are not permitted ratio units such as%, ‰, ppb and ppm and mg% and g% (= g/100 ml)

ρ _B = m _B / v _Lg

5 Volume concentration
The volume concentration of a substance B in a mixing stage is defined as the quotient of the volume of the substance B, and the total volume of the mixing phase.
The corresponding SI unit is m³ / m³. Furthermore permitted are l / l, l / m³, cm ³ / l and l / hl.

σ _B = v _B / v _tot

6 Amount of substance
The amount of substance (mole fraction called) of a substance B in a mixed phase is defined as the quotient of the molar amount of the substance B and the sum of the molar amounts of all components of the mixed phase.
The SI unit is mol / mol, and mmol / mol, mol / kmol,% ‰, ppm and ppb are permitted.

χ _B = n _B / n Σ _i

7 Mass fraction 
The mass fraction (also called mass fraction) of a substance B in a mixed phase is defined as the ratio of the mass of the substance B and the sum of the masses of all the components of the mixed phase.
The associated SI unit is kg / kg, g / kg, mg / g, mg / kg, g / g% ‰, ppm and ppb are also permitted.

w _B = m _B / m Σ _i

8 Volume fraction 
The volume fraction (also called the volume fraction) of a substance B in a mixing stage is defined as the quotient of the volume of the substance B and the sum of the volumes of all components of the mixed phase.
The SI unit is m³ / m³. Furthermore, are permitted: l / l, l / m³, cm ³ / l, ml / l,%, ‰, ppm and ppb.

φ _B = v _B / v Σ _i

Conversion of concentration variables