Question

1.00 g of a non-electrolyte solute dissolved in 50g of benzene lowered the freezing point of benzene by 0.40 K. The freezing point depression constant of benzene is 5.12 K kg `mol^(-1)`. Find the molar mass of the solute.

Answer 1

Substituting the values of various terms involved in equation
`M_(2)=(K_(f)xx w_(2)xx1000)/(DeltaT_(f)xx w_(1))` we get,
`M_(2)=(5.12" K kg mol"^(-1)xx1.00" g"xx1000" g kg"^(-1))/(0.40xx50" g")=256" g mol"^(-1)`
Thus, molar mass of the solute `=256" g mol"^(-1)`