This normally happens
in solvents of low dielectric constant In this case the number
of particles is reduced due to dimerisation Association of
molecules is depicted as follows:
It can be undoubtedly stated here that if all the molecules of ethanoic
acid associate in benzene, then DTb or DTf for ethanoic acid will be half
of the normal value The molar mass calculated on the basis of this DTb
or DTf will, therefore, be twice the expected value