Question

What do you understand by the association of solute molecules in solution?

Answer 1

In solution, some solutes experience molecular association, which is the process by which their molecules group together to form aggregates. A dimer is the aggregate that results from the combination of two solute molecules. An aggregate made up of three molecules is called a trimer, one made up of four molecules is called a tetramer, and so forth. For instance, two molecules of benzoic acid combine to form a dimer when it dissolves in benzene, as shown below.

\[\ce{\underset{Benzoic acid}{2C6H5COOH} <=> \underset{Dimer of benzoic acid}{(C6H5COOH)2}}\]

When association occurs, some of the solute particles combine together to create a single particle, resulting in fewer particles in the solution than would be predicted.