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(a) Define the following terms : (i) M...

(a) Define the following terms :
(i) Mole fraction
(ii) Ideal solution
(b) `15.0`g of an unknown molecular material is dissolved in 450g of water . The resulting solution freezes at `-0.34^(@)C` . What is the molar mass of the material ?
`(K_(f)` for water = `1.86` K kg `mol^(-1))`

Text Solution

Verified by Experts

(b) `Delta`mix H = 0 `Delta`mix V = 0
`DeltaT_(f) = K_(f)X` molality
`DeltaT_(f) = (1.86 xx 15.0 xx 1000)/(M xx 450)`
`M = (1.86 xx 150 xx 1000)/(0.34 xx 450)`
`M = 182.3` gm `mol^(-1)`.
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