When 1.94 g of vitaminK is dissolved in 25.0 g of camphor, the freezing point of the sol'n is lowered by 6.51∘C. What's the molarmass of vK.?

1 Answer

  • 8 months ago

    I found the Kf for camphor to be 37.7 C/m (If that is not the value you are given, just replace that in the calculation below and recalculate.)

    Calculate the molality of the solution:

    Delta Tf = Kf m

    6.51 C = 37.7 C/m (m)

    m = 0.1727 m = 0.1727 moles vitamin K / kilogram camphor

    The solution was made with 1.94 g vitamin K/0.025 kg camphor = 77.6 g/kg

    Dividing those two values gives:

    77.6 g/kg / 0.1727 mol/kg = 449 g/mol

    The accepted value for its molar mass is 450.7 g/mol

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