Making a gold solution for plating.

[MaximumTaco]

Hi,

I'm trying to figure out how to dissolve metallic Au in solution, for an electroplating solution, without the use of Nitric Acid, Cyanides, or other chemicals which i cannot obtain.

I can obtain many more common (less suspicious and dangerous) chemicals, such as concentrated HCl, H2SO4 and H2O2, NaOH, Urea, and many other things.

I thought about distilling conc. H2SO4 out of KNO3 but i don't have a proper distillation apparatus that will handle this.

I read somewhere that a Urea solution will complex with gold, forming a solution - is this right? does anyone know the details needed to make this work?

Could trichloroisocyanauric acid, or Na dichloroisocyanaurate, having a structure derived from cyanide, be used to form a suitable solution?

 

[ShawnD]

I can obtain many more common (less suspicious and dangerous) chemicals, such as concentrated HCl, H2SO4 and H2O2, NaOH, Urea, and many other things.

I thought about distilling conc. H2SO4 out of KNO3 but i don't have a proper distillation apparatus that will handle this.

alone, none of those will do anything. The standard electrode potential of gold is 1.5V.
H2SO4 is only 0.17V, HCl is not an oxidizer, NaOH is a reducer, and urea complexes are only formed when ions mix (the gold would need to be already dissolved). Even HNO3 is too weak at 0.8V

Try mixing HCl, KNO3, and a little bit of urea together. Don't panic if it foams since urea is a base. Throw in a little tiny piece of gold and see if it dissolves.
The idea is that the voltage is more spontaneous when the gold concentration is low and the acid/nitrate concentration is high. What the urea complex does is in a sense "remove" gold ions from the mixture so the reaction is still spontaneous.
Don't get your hopes up though. I wouldn't expect it to work with anything less than concentrated HCl with concentrated nitric acid.

 

[dextercioby]

The mixture of $\mbox{HCl}$ and $\mbox{HNO}_{3}$ in a ratio of 1:3 will dissolve gold giving trichloride of Aurum.

Daniel.

 

[pack_rat2]

The mixture of $\mbox{HCl}$ and $\mbox{HNO}_{3}$ in a ratio of 1:3...

"Royal Water"...;)

 

[ShawnD]

The mixture of $\mbox{HCl}$ and $\mbox{HNO}_{3}$ in a ratio of 1:3 will dissolve gold giving trichloride of Aurum.

Where would he got from here? How do you dissolve gold chloride?


I thought of another way you could go about doing this. You can dissolve the gold with potassium permanganate (Condy's Crystals at the pet store) in strong base like sodium hydroxide (Drano or degreaser).
-permanganate dissolves the gold
-hydroxide precipitates the gold

Filter the precipitate from the solution, then add nitric acid to dissolve the gold hydroxide.

 

[MaximumTaco]

Hmm, that sounds good. I have plenty of KMnO4 and NaOH

But no Nitric Acid.