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 Such a molar mass
that is either lower or higher than the expected or normal value is called
as abnormal molar mass