text: Similarly, if a fraction  of  moles of solute associate to form one mole of an n-mer (dimer, trimer, etc.), then
  For the dimerisation of acetic acid in benzene:
  : 2 CHCOOH  (CHCOOH)
  2 moles of acetic acid associate to form 1 mole of dimer, so that
  For association in the absence of dissociation, the van 't Hoff factor is: