Chloroauric acid sodium ascorbate

With rapid mixing of the chloroauric acid/carbonate solution, quickly add 1ml of a 7 percent sodium ascorbate solution prepared in water. Maintain the solution cooling in an ice bath. Higher temperatures will create larger particle sizes. The color of the solution at this point will turn to a purple-red. 

Ascorbate reduction This method (7) entails the fairly rapid addition of sodium ascorbate to chloroauric acid while stirring. If the reaction is carried out on ice, the gold particle size range is between 6 and 8 nm. Higher temperatures tend to increase the particle size The method is also really of academic interest nowadays, since it is not easy to control the final sphere diameter. 

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