posted by Paula .
Sometimes as a solute dissolves in a solvent, the solute molecules dissociate to some extent. Sometimes solute molecules associate to form larger molecular units, such as dimers or trimers. Discuss the effect of dissociation and of association on the apparent molecular weight of a solute.
Discussions are for you to do. Basically, however, you want to include in your discussion that dissociation makes the apparent molar mass smaller and association makes the apparent molar mass larger.