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On dissolving 0.25 gof a non-volatile su...

On dissolving `0.25 g`of a non-volatile substance in`30 mL` benzene `(density 0.8 g mL^(-1))`, its freezing point decreases by `0.25^(@)C` . Calculate the molecular mass of non-volatile substance `(K_(f) = 5.1 K kg mol^(-1))`.

Text Solution

Verified by Experts

Mass of benzene,W =Volume `xx` Desity
`= 30xx0.8 =24 g`
Given,`K_(f) = 5.12 K kg mol^(-1), W_(2)=0.25 g`
`DeltaT=0.25^(@)C`,
We know that
`Mw_(2) =(1000K_(f)xxW_(2))/(W_(1)xxDeltaT)` (substituting all values)
=`(100xx5.12xx0.25)/(24xx0.25)=213.33`
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