where we have included the standard concentration, C • , which is equal to 1 mol L -1 and can be effectively omitted. In turn, the stoichiometric concentration of phenol, C 0 , assuming that only aggregates up to tetramers exist, is given by C 0 = 4 n=1 nC n . This mass-conservation condition, together with all three self-association equilibria, Eq. ( ), complete a system of four equations whose solution provides the concentration of the monomer and the three aggregates.