Question

Describe Bredig’s arc method used for the preparation of metal sols.

Answer 1

Bredig’s arc method is an electrical dispersion technique used to prepare metal sols like gold, silver, and platinum. An electric arc is struck between two metal electrodes immersed in a cooled dispersion medium (e.g., water surrounded by a freezing mixture). The high temperature vaporizes some metal, which then condenses into colloidal-sized particles on cooling. These particles disperse in the medium, forming a stable metal sol. This method effectively produces lyophobic sols of metals.