question_answer

  2 g of benzoic acid  dissolved in 25 g of benzene shows a depression in freezing point equal to 1.62 K. Molar depression constant for benzene is 4.9 K kg . What is the percentage association of acid if it forms dimer in solution?                                                                                                                                                            [3]

Answer:

  Dimer formation is by intermolecular H-bonding.                                                              i=van't Hoff factor                                                                                          [1]                                       Dimer formation = 99.16%                           [1]