Question

Describe the method for the preparation of gold colloidal sol with diagram.

Answer 1

Gold colloidal sol is prepared by Bredig's arc method (electro dispersion). Electric arc is struck between two electrodes of gold metal. Electrolyte is water having traces of alkali. Gold vapourises due to heat and then condenses into electrolyte due to cooling. Collodial solution of gold is obtained. Alkali is a stabiliser.