Question

A freshely prepared $Fe(OH{)}_3$ precipitate is peptized by adding a solution of $FeC{l}_3$. The charge on colloidal particle is due to the preferential adsorption of:

• A. $C{l}^{-}$ ion
• B. $F{e}^{3+}$ ion
• C. $O{H}^{-}$ ion
• D. $B{a}^{2+}$ ion

Answer 1

The correct option is B $F{e}^{3+}$ ion

Peptization is a process of converting a precipitate into a colloidal sol by shaking it with a dispersion medium in the presence of a small quantity of an electrolyte. Since $F{e}^{3+}$ is common in both $Fe(OH{)}_3$ and $FeC{l}_3$, hence $F{e}^{3+}$ is preferentially absorbed. The charge on the colloidal particle is due to preferential adsorption of $F{e}^{3+}$