Question

 Predict whether van’t Hoff factor, (i) is less than one or greater than one in the following: 
CH₃COOH dissolved in water 

Answer 1

van't hoff factor i = `"total number of moles of particles after  dissociation association"/"no.of moles of particls before association dissociation"`

(i) CH3COOH
\[\ce{CH3\underset{1}{C}OOH->[H2O]CH3\underset{1}{C}OO- \underset{+1 = 2}{+H+}\text{(dissociation)} }\]
`i = 2/1 =2 ` (i is greater 1)

(ii) CH3COOH dissolved in benzene

\[\ce {2C\underset{2}{H}3COOH ->[benzene]\underset{1\text{(due to H-bonding)}}{CH3COOH}2}\]  (association)

                                             1(due to H-bonding)

`i= 1/2=0.5` (i is less than 1)