substance X forms trimer when added to Benzene calculates the freezing point of the 0.25 molal solution. The degree of association of the solute is found to be 0.80. The freezing point of the benzene is 5.5oC and its Cryoscopic constant is 5.12 K m-1.

Asked by Topperlearning User | 4th Jun, 2014, 01:23: PM

Expert Answer:

                                              3X               X3
   initial number of moles       3                 0
   final number of moles        m (1-α)        mα/3
   total number of moles after association =     m (1-α) + mα/3    = m (1-2α/3)
                                                                 = 0.25 (1-2x0.80/3)
                                                                 = 0.177m
                                                                ΔTf = Kf m
                                                                        =5.12 x 0.177= 0.6

        Tf (solution) = 278.65K-0.06K= 278.59K

Answered by  | 4th Jun, 2014, 03:23: PM