Question

Explain the following term:

Peptization

Answer 1

Peptization is the process of converting a freshly prepared precipitate into a colloidal solution by adding a suitable electrolyte called a peptizing agent. This agent adsorbs onto the precipitate particles, imparting like charges that cause electrostatic repulsion among them. This repulsion disperses the particles uniformly, stabilizing the colloid. For instance, adding ferric chloride to freshly precipitated ferric hydroxide produces a reddish-brown colloidal ferric hydroxide solution by Fe³⁺ ion adsorption. Another example is shaking freshly precipitated silver iodide with dilute silver nitrate to obtain a colloidal solution. Peptization is crucial in preparing and stabilizing lyophobic sols in colloidal chemistry.