What is Van't Hoff factor ? Under what conditions Van't Hoff factor is
(i) `gt 1`
(ii) =1
`lt ` 1. Explain .

Explanation

Van.t Hoff factor (i) is the rate of natural molecular mass `(M_(a))` to the observed molecular mass `(M_(a))`
`i=(M_(n))/(M_(0))`
(i) Now, i `gt` 1 when `M gt M_(0-)`. This can happen in case of electrolytes when the solute undergoes dissociation in solution and thus corresponds to lower value of molar mass that is observed fTom measurement of colligative property.
(ii) i = 1 when `M_(n) = M_(0)`. This can occur if the solute does not undergo dissociation or association in solution.
(iii) `i lt 1` when `M_(n) lt M_(0)` This can happen if the solute undergoes association in solution so that the value of observed molar mass becomes larger.