The van’t Hoff factor(i) for a compound which undergoes dissociation in one solvent and association in other solvent is respectively 

From the value of van’t Hoff factor ,  it is possible to determine the degree of dissociation or association. 

In case of dissociation, i is greater than 1 ; $\mathrm{i}=1-\mathrm{\alpha }+\mathrm{n\alpha }$

 In case of association i is lesser than 1; $1-\mathrm{\alpha }+\frac{\mathrm{\alpha }}{\mathrm{n}}$