For a solute that dissociates in solution and one that associates, the van't Hoff factor i is respectively:

1. Dissociation increases the number of particles, so observed colligative effect rises and i > 1 (e.g. KCl, i near 2). 2. Association decreases the number of particles, so i < 1 (e.g. ethanoic acid in benzene, i near 0.5). 3. Hence dissociation gives i > 1 and association gives i < 1. _Source: syllabus Chemistry Ch 1 "Solutions", p.23_