* When solute particles associate in solution,  is less than 1. For example, carboxylic acids such as acetic acid (ethanoic acid) or benzoic acid form dimers in benzene, so that the number of solute particles is half the number of acid molecules.
* When solute particles dissociate in solution,  is greater than 1 (e.g. sodium chloride in water, potassium chloride in water, magnesium chloride in water).
* When solute particles neither dissociate nor associate in solution,  equals 1 (e.g. glucose in water).
The value of  is the actual number of particles in solution after dissociation divided by the number of formula units initially dissolved in solution and means the number of particles per formula unit of the solute when a solution is dilute.