Question

Phenol `(C_(6)H_(5)OH)` is found to exist as polymer. If there is `100%` polymerisation, determine number of phenol molecules polymerised inaqueous solution if `9.4g` aqueous solution in `100g` water freezes at `-0.93^(@)C`.
`K_(l)(H_(2)O)=1.86^(@)"mol"^(-1)kg`

Answer 1

Correct Answer - `n=2`
Let number of phenol molecules undergoing polymerisation `=n`

`therefore i=[1+(y-1)x]=[1+((1)/(n)-1)x]`
`=1+((1)/(n)-1)` since, `x=1`
`i=(1)/(n)`
`DeltaT_(f)=1000K_(f)(w_(1))/(m_(1)w_(2))(i)`
`0.93=1000xx(1.86xx9.4)/(94xx100)` (i)
`i=(1)/(2)=(1)/(n)`
`therefore n=2`