Gold Sol is Colloidal Gold. Gold Sol can be produced by boiling a solution of tetracholoroauric acid with a reducing agent. At the beginning of the reduction process the gold atoms are liberated from the chloroauric acid.
Meaning
Gold sol is a special type of collide which is known as lyophobic sol which are liquid hating or solvent hating i.e., these sols do not have liquid as solvent. In such sols, both the dispersed phase and dispersion medium is solid only. A gold sol may contain particles of various size composed of several atoms of gold and so it is called as multimolecular sol.
Abstract
The formation of uniform gold sols produced by the citrate reduction of auric acid is explored as a function of temperature and reagent concentration. As aurate ions are reduced, the reaction medium changes from black to purple to blue before turning deep red. These color changes are shown to result from a decrease in particle size over the course of the reaction. Electrophoretic and titration studies suggest the colloidal properties of the sols result from a combination of van der Waals, electrostatic, and short-range repulsive interaction potentials. Increases in particle surface potential over the course of the reaction are shown to result from competitive adsorption of citrate and aurate ions. A particle growth model incorporating colloidal stability is postulated.