Making a gold solution for plating.

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In summary, trying to dissolve metallic Au in solution using only common chemicals is not possible. The standard electrode potential of gold is 1.5V.
  • #1
MaximumTaco
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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?
 
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  • #2
MaximumTaco said:
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.
 
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  • #3
The mixture of [itex] \mbox{HCl} [/itex] and [itex] \mbox{HNO}_{3} [/itex] in a ratio of 1:3 will dissolve gold giving trichloride of Aurum.

Daniel.
 
  • #4
dextercioby said:
The mixture of [itex] \mbox{HCl} [/itex] and [itex] \mbox{HNO}_{3} [/itex] in a ratio of 1:3...
"Royal Water"...;)
 
  • #5
dextercioby said:
The mixture of [itex] \mbox{HCl} [/itex] and [itex] \mbox{HNO}_{3} [/itex] 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.
 
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  • #6
Hmm, that sounds good. I have plenty of KMnO4 and NaOH

But no Nitric Acid.
 

1. How do you make a gold solution for plating?

Making a gold solution for plating requires a process called electroplating. This involves immersing a gold anode and the object to be plated (cathode) in a solution containing dissolved gold. An electrical current is passed through the solution, causing the gold ions to adhere to the object, creating a thin layer of gold plating.

2. What concentration of gold is needed for plating?

The concentration of gold needed for plating depends on the desired thickness of the gold layer on the object. Generally, a concentration of 1-5 grams of gold per liter of solution is sufficient for most plating processes.

3. How is the quality of the gold solution for plating determined?

The quality of the gold solution is determined by its purity and consistency. The purity of the gold can be measured using techniques such as spectroscopy or titration. The consistency of the solution can be tested by monitoring its conductivity and pH levels.

4. What factors can affect the quality of the gold solution for plating?

Several factors can affect the quality of the gold solution, including the purity of the starting materials, the temperature and pH of the solution, and the current and voltage used for electroplating. It is important to maintain these variables within the desired range for consistent and high-quality plating results.

5. Can a gold solution for plating be reused?

Yes, a gold solution can be reused multiple times, as long as it is properly maintained and replenished with fresh gold ions. However, over time, the solution may become depleted, and it may be necessary to create a new solution by dissolving more gold into the electrolyte.

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