JEE Main · 2019 · 12 Apr 2019 · Shift 1 · Surface Chemistry

Peptization is the reverse of coagulation. A freshly made precipitate is dispersed back into a colloidal sol by adding a small amount of a suitable electrolyte, the peptizing agent, whose ions are adsorbed on the particles and charge them so they repel one another instead of clumping. For example, fresh $\mathrm{Fe}(\mathrm{OH}){}_3$ can be peptized by a little $\mathrm{FeCl}{}_3$. So peptization is the process of converting a precipitate into a colloidal solution.