[thdbird83]

Hi

I would like to know what is the chemical reaction invlove in gold solution (aqua reqia) with sodium sulfide (or sulfite i m not sure which is it)?  






By the way if u guys are wondering why ask so many question on gold? the answer is that i m working on a gold project for school.

[eugenedakin]

Hello thdbird83,

There are two sets of reactions... One is by using alkali sulphites or sulphur dioxide...

1) Alkali sulphites or sulphur dioxide can easily reduce gold trichloride.

2) Thiosulphates are typically used when both gold and silver are present..
8Na₂S₂O₃+2AuCl₃--> Au₂S₂O₃*3Na₂S₂O₃+2Na₂S₄O₆+6NaCl
The use of thiosulphates is newer technology..

I wish you the best with your project for school,

Eugene

[eugenedakin]

Oops.. there was a little more information with the Gold Thiosulphates...

The double gold thiosulphate can be separated by precipitation with a strong alcohol, washed with water, and reprecipitated with alcohol... Metallic gold and sodium thiosulphate are formed...

Sincerely,

Eugene