What is van't Hoff factor in each of the following cases?
(A) Aq. K_(4)[Fe(CN)_(6)]` which is `20%` inosed
(B) `PCl_(5)` which is `50%` dissociated
(C) Benzoic acid which forms dimer to the extents of `50%` in benzene
(D) Glucose solution

Explanation

(A)
`i`(van'tHOff factor) `=[1+(y-1)x]`
`1+4x=1+4xx0.2=1.8`
(B)
`i=[1+(y-1)x]=1+x=1+0.5=1.5`
(C) `2C_(6)H_(5)COOOHhArr(C_(6)H_(5)COOH)_(2)`
`C_(6)H_(5)COOHhArr(1)/(2)(C_(6)H_(5)COOH)_(2)`
`y=(y)/(2)`
Dimer formation is due to intermolecular `H-`bonding.

`i=[1+(y-1)x]=1-(x)/(2)=1-(0.5)/(2)`
`=0.75`
`i=1+(y-1)x,y(1)/(2)`
`i=1+((1)/(2)-1)xx=1-(0.5)/(2)`
(D) There is no change in the molecular state of glucose being a non-electolyte. Hence, `y=1
i=[1+(y-1)x]=1`