Author Topic: Making Gold Chloride  (Read 16226 times)

Offline kephra

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Re: Making Gold Chloride
« Reply #45 on: November 29, 2016, 01:00:38 PM »
Yes, thats the basic process. 
In the final step, you should not add 10ml of water.  You should add enough water to make 10ml.  EG: 10ml minus the volume occupied by the gold chloride.  Its a small error, but thats the correct way to make a percentage dilution. 
There is the unknown and the unknowable.  It's a wise man who knows the difference.

MagnumOpus

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Re: Making Gold Chloride
« Reply #46 on: November 29, 2016, 04:22:08 PM »
Yes, thats the basic process. 
In the final step, you should not add 10ml of water.  You should add enough water to make 10ml.  EG: 10ml minus the volume occupied by the gold chloride.  Its a small error, but thats the correct way to make a percentage dilution.

Ok perfect, thanks kephra. I noticed a small amount of fine black dust has settled on the bottom of the graduated cylinder. I'm thinking either my HCl is dirty (commercial grade for swimming pools) or maybe the glass was not as clean as I thought it was and some contaminants were oxidized by the H2O2. I'll be cleaning my glass thoroughly and feeding this batch to some house plants.

Does anyone know where I could buy some clean, reagent or lab grade HCl in Canada?
« Last Edit: November 30, 2016, 02:02:22 AM by MagnumOpus »

MagnumOpus

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Re: Making Gold Chloride
« Reply #47 on: November 30, 2016, 02:21:40 AM »
Previously I used a little known method using table salt, citric acid and H2O2 to dissolve gold but I found that the end product was too acidic. When producing the colloidal gold I had to add a lot of sodium carbonate to neutralize the acidity which caused the solution to be too salty. I could only get a purple colloid using this method which is undesirable and it fell out of solution very quickly. I would love to refine this method though considering how easy it is to obtain the necessary ingredients and the fact that it's much safer than the alternatives. The process I found was quite crude:

Add salt and citric acid to 3% food grade H2O2, slightly more citric acid than salt (amounts were not specified so I started out with a ratio of 1tsp:1.33tsp and 50mls H2O2, not all of the salts dissolved so I kept adding more H2O2 until they did). Add gold leaf and heat to a simmer until the gold dissolves.

It took at least 5 to 6 hours to dissolve a few sheets of gold leaf (I'm in no rush anyway), I think with 35% H2O2 it would work much quicker but I'd be shooting in the dark trying to figure out the optimal ratios myself. Could anyone here with a more thorough knowledge of chemistry chime in and work out a rough estimate of the ratios I should be using to achieve an optimal result? I know that diluting with water and boiling this down is not going to remove excess acidity since it's from citric acid. I would need to have just enough to react with the gold to produce AuCl or whatever compound this results in (anyone know?). I just don't trust the commercial HCl that's available here for consumption of the end product so this is what I have to work with for now.

tseax

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Re: Making Gold Chloride
« Reply #48 on: November 30, 2016, 12:27:45 PM »
Does anyone know where I could buy some clean, reagent or lab grade HCl in Canada?

I got mine from a local company providing geological and laboratory supplies. Had to fill out TDG paperwork just to drive it home. It was 35% as i recall - Fisher brand, laboratory grade.

Offline kephra

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Re: Making Gold Chloride
« Reply #49 on: November 30, 2016, 02:34:54 PM »
Magnum:

To make gold chloride (AuCl3) you need 3 atoms of chlorine for each atom of gold.
An atom of gold weighs 196 daltons, and a molecule of sodium chloride weighs about 58 daltons
Then to combine 196 daltons of gold you need 174 daltons of sodium chloride.

Citric acid does not help in dissolving gold. 

The purpose of the peroxide or nitric acid or electric field is to strip the 3 electrons from the gold atoms so they can combine with the chlroride.  Gold will not form oxides, or nitrates.

The reactions using peroxide are (assuming 100% efficiency are):

Au + 1.5H2O2 -->  2Au+++  +3OH-
Au+++ + 3NaCl  --> AuCl3  + 3Na+
3Na+ + 3OH- --> 3NaOH

You can see from the reactions that no gas should be evolved, so any gas bubbles represent peroxide that is lost to some other spontaneous reaction, making the needed amount of peroxide higher.

So for 1 gram of gold, you need (minimum) 174/196 grams of sodium chloride.
You also need 1.5/0.03 ml of 3% peroxide (about 50ml).  In practice you will need more.

The spontaneous decomposition of peroxide is:
2H2O2  -->2 H2O +O2 
The unknown is how much of the peroxide will decompose.
There is the unknown and the unknowable.  It's a wise man who knows the difference.

MagnumOpus

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Re: Making Gold Chloride
« Reply #50 on: November 30, 2016, 04:26:43 PM »
kephra:

I thought the citric acid was required to help form a weak acid solution so the electrons could be more easily stripped from the gold. So you're saying that sodium chloride + H2O2 alone should eventually dissolve the gold with a little heat? That would be very impressive!

Offline kephra

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Re: Making Gold Chloride
« Reply #51 on: November 30, 2016, 10:21:56 PM »
I have never heard of using citric acid to dissolve gold.  You need a strong oxidizer plus chloride.  Nitric acid, hydrogen peroxide, or positive electricity are strong oxidizers.  Citric acid is a weak oxidizer.  There is at least one youtube video showing the peroxide method of dissolving gold, and I think forum members have also used that method with some results.
« Last Edit: November 30, 2016, 10:52:05 PM by kephra »
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MagnumOpus

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Re: Making Gold Chloride
« Reply #52 on: December 01, 2016, 06:02:06 PM »
So for 1 gram of gold, you need (minimum) 174/196 grams of sodium chloride.
You also need 1.5/0.03 ml of 3% peroxide (about 50ml).  In practice you will need more.

I'm going to give this a try soon, I'll be using 35% food grade peroxide though. I will try working with 100mg of gold leaf to start out, cutting the portions you shared by 1/10. Does this process look okay:

Add enough distilled water to 89 mg (174/196/10) of sodium chloride to create a saturated salt solution, leaving a little excess salt in the bottom to be dissolved when the solution is heated.
Heat the salt solution to a simmer, add my gold leaf and then slowing add 35% a few drops at a time,  just enough to keep the reaction going.
Check on it periodically, adding more peroxide as needed to fully dissolve the gold leaf.

If this doesn't work out as planned, I've been thinking about using bleach + peroxide. Do you think household bleach would be safe to use for creating colloidal gold? If not, what about creating gold chloride via electrolysis instead of colloidal gold directly? Reason being that the colloid created from AuCl seems to be more stable.

Offline kephra

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Re: Making Gold Chloride
« Reply #53 on: December 01, 2016, 06:05:58 PM »
Quote
Reason being that the colloid created from AuCl seems to be more stable
Yes, thats because there is less other stuff like salt in the water.
I don't know about bleach, I have never tried it, and with my aversion to it, I am not likely to.
There is the unknown and the unknowable.  It's a wise man who knows the difference.

MagnumOpus

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Re: Making Gold Chloride
« Reply #54 on: December 01, 2016, 06:28:35 PM »
That makes perfect sense. Does the process I described above sound like it would work? I guess I should just get off my armchair and try it right.. haha  ;D Worst case it doesn't dissolve and I can easily recover the gold leaf.
« Last Edit: December 01, 2016, 06:51:12 PM by MagnumOpus »

Offline kephra

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Re: Making Gold Chloride
« Reply #55 on: December 01, 2016, 11:35:29 PM »
I think you will do better with HCL instead of salt though.  Pool supply places may have hydrochloric acid that is food grade.  Pool chemicals are required to be food grade in the US at least.
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MagnumOpus

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Re: Making Gold Chloride
« Reply #56 on: December 02, 2016, 12:13:40 AM »
I've been trying to track down some pool grade HCl but it's winter here now and all the places I checked didn't have any specifically for pools (all the pool supply places are closed for the season) but I found some that says "Cleaning, Etching, Descaling" on the front and on the back it has instructions for lowering pH in pools so I figured I would give it a try. I also checked the MSDS and it states that it's just distilled water and HCl @ 31.45% 20 Baume. I'm just weary of any harmful contaminants might be in there since it's commercial grade. Although considering how it's typically produced on large scale I can't see there being much else in there, unless they lied and used spring/tap water... Correct me if I'm wrong on this point please.

I'm having a hard time finding a detailed process of producing gold chloride via electrolysis with NaCl, virtually all of the hits I get are dealing with extraction or electroplating. I find it strange that info is difficult to locate, and I'm someone who can usually find just about anything you can imagine using advanced wildcard searches. Maybe because it's just as simple as I assume (salt + gold anode + ~30V 250 to 500mA).  I should be able to use your process for producing colloidal gold and just leave out the sodium citrate. Boil out the water when it's finished and I should be left with very pure AuCl3 right?

Thank you so much for taking the time to respond to these questions by the way Kephra. I'm a little rusty on my chemistry but determined to get back into the swing of things.

Offline kephra

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Re: Making Gold Chloride
« Reply #57 on: December 02, 2016, 01:15:32 AM »
Quote
I'm having a hard time finding a detailed process of producing gold chloride via electrolysis with NaCl, virtually all of the hits I get are dealing with extraction or electroplating. I find it strange that info is difficult to locate, and I'm someone who can usually find just about anything you can imagine using advanced wildcard searches. Maybe because it's just as simple as I assume (salt + gold anode + ~30V 250 to 500mA).  I should be able to use your process for producing colloidal gold and just leave out the sodium citrate. Boil out the water when it's finished and I should be left with very pure AuCl3 right?
As far as I know, I am the only one to come up with an electrolysis method.  Its not as good simply because there is no way to know the actual gold ppm, and it will have salt left over in the solution.   But quite a few people are using my method when they can't buy gold chloride.
Try the Electrolysis III with the maltodextrin first.  Maltodextrin is a better reducing agent than sodium citrate.  I would go higher on the voltage if possible.  I initially used a Radio Shack power supply which was marked 30 volts but actually produced 36.

7 years ago, I made a video of making colloidal gold using sodium citrate.  The formulas on the forum here are better, but it will show the basic idea.
https://www.youtube.com/watch?v=RE2hVh7iJvY

There is the unknown and the unknowable.  It's a wise man who knows the difference.