1.

3.9 g of benzoic acid dissolved in 49 g of benzne shows a depreesionin freezingpointof 1.62 K. Calculate the van't Haff factorand predict the natureof solutei(associated or dissociated ). [Given:Molarmass of benzoic acid= 122g mol^(-1), K_(f) for benzene = 4.9 K kgmol^(-1)].

Answer»

Solution :`Delta T_(F) = ik_(f) XX m`
` = (ixxk_(f) xx w_(B) xx 100)/(M_(B) xx w_(A))`
` 1.62= (ixx4.9 xx 3.9 xx 1000)/(122xx49)`
` or "" i= (1.62 xx122xx49)/(4.9 xx 3.9 xx 1000) = 0.506`
Since .i.is lessthanone the solute is associated .


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