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1.00 g of a non-electrolyte solute disso...

1.00 g of a non-electrolyte solute dissolved in 50 g 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.

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The correct Answer is:
256 g `"mol"^(-1)`
`K_(f)=5.12" K kg mol"^(-1), DeltaT_(f)=0.40K`, weight of solute = 1.00g
Weight of solvent benzene = 50.0 g
`DeltaT_(f)=K_(f) xx m=(K_(f) xx "Weight of solute" xx 1000)/("Mol. Mass of solute" xx "weight of solvent")`
or `0.40=(5.12xx1xx1000)/(M_(2) xx 50.15)`
or `M_(2)=(5.12 xx 1xx1000)/(0.40xx50.0)=256"g mol"^(-1)`
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