Rough experiment of dissolution/deposition ofgold In order to estimate dissolution rate ofgold in HOS and how much ascorbic acid needs to be precipitated gold, model experiment has been carried out. 1. A gold wire (ca. 1m, 0.2mm in diameter) was added into HOS (40ml) of I 2 (6mmol), NaI (6mmol) and ethanol (29.1g) with stirring at room temperature. 2. After a hour, 10 ml HOS containing gold was separated, and used for deposition experiments using ascorbic acid and water.
1. Dissolution This graph shows dissolution ofgold into HOS with time. In first a hour, there is immediate sharp rise in dissolution ofgold. After a hour, dissolution ofgold slightly increase. It is likely to achieve equilibrium. If gold was saturated in 0.1g at room temperature, It can be estimated 0.1mol ofgold can dissolve in HOS with I 3- of 1mol. The increase temperature caused a rapid growth of dissolution ofgold.