The van't Hoff factor (i) for a dilute solution of K₃[Fe(CN)₆] is:

${\mathrm{K}}_3\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]\rightleftharpoons 3{\mathrm{K}}^{+}+\mathrm{Fe}(\mathrm{CN}{)}_6^{3-}$

$\begin{array}{ccc}1& 0& 0\\ 1-\mathrm{\alpha }& 3\mathrm{\alpha }& \mathrm{\alpha }\end{array}$

$\text{ van't Hoff factor }\mathrm{i}=1-\mathrm{\alpha }+3\mathrm{\alpha }+\mathrm{\alpha }=1+3\mathrm{\alpha }$

In very dilute state $\alpha$ = 1; Thus i = 4.