Author Topic: Making Gold Chloride  (Read 16228 times)

tseax

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Re: Making Gold Chloride
« Reply #30 on: October 17, 2015, 02:32:25 AM »
what the heck was the precipitate?
gold
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did you use 9999 gold?
you bet
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your reactions after adding H2O2 looked a little vigorous..too much heat, would be my guess.
How much heat is too much? Was 80-degrees C (+ or - 5-degrees).

low_tech

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Re: Making Gold Chloride
« Reply #31 on: October 18, 2015, 11:21:29 PM »
so I took 50 ml 2% gold chloride and warmed it to about 180F and added 20 ml  35% H2O2 and it did the same thing..  Precipitated the gold out of solution.


too hot, or too much H2O2....

when I an working on dissolving gold, my temperature of solution really does not go above 130 degrees F   at some point the the reaction speed is too fast and the gold precipitates. 

tseax

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Re: Making Gold Chloride
« Reply #32 on: October 19, 2015, 02:40:31 AM »
so I took 50 ml 2% gold chloride and warmed it to about 180F and added 20 ml  35% H2O2 and it did the same thing..  Precipitated the gold out of solution.
:(
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too hot, or too much H2O2....
I would guess...
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when I an working on dissolving gold, my temperature of solution really does not go above 130 degrees F   at some point the the reaction speed is too fast and the gold precipitates.
This is getting to the point where it deserves a sticky  ;)  Hint, hint...

Offline PeterXXL

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Re: Making Gold Chloride
« Reply #33 on: January 09, 2016, 08:09:25 PM »
<snip>Simply speaking, dissolving 2.616 gms Au (by way of HAuCl4) in 174.4 mL H20 will provide a 1.5% solution of HAuCl4. 1 mL of this should provide 15 mg of Au in our nukerator recipe.

Or more exactly 14.55 mg, as 2500 / 174.4 = 14.33 mg

BTW, how long time did it take for you to dissolve the 2.616 gram gold?

I'm asking, 'cause with 17.5% peroxide  it goes very slowly. During 1 hour only 310 mg gold was dissolved (I stopped then as I did not had time to continue, but during that hour the 30% HCl was near boiling temp, and I constantly poured little H2O2 into it and could see the bubbling reaction. And finally weigthed it in a digital scale.

And this is also the reason why I prefer to use the traditional "aqua regia" combination of HCl and HNO3 instead of this method with HCl and H2O2. With the latter method the gold dissolves much faster, even though the fumes are more toxic.





tseax

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Re: Making Gold Chloride
« Reply #34 on: January 10, 2016, 05:40:11 PM »

BTW, how long time did it take for you to dissolve the 2.616 gram gold?
As I recall it took about 8-hours split over 2-days. Too long.
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And this is also the reason why I prefer to use the traditional "aqua regia" combination of HCl and HNO3 instead of this method with HCl and H2O2. With the latter method the gold dissolves much faster, even though the fumes are more toxic.
I'll be trying your aqua regia method as soon as I get a fume hood  ;)

All2

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Re: Making Gold Chloride
« Reply #35 on: February 10, 2016, 03:38:42 AM »
I have done the HCL + H2O2 + heat + time on gold, copper and platinum, it works on all of them however Pt takes really long, got 60% in 6 weeks  ;)

anax

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Re: Making Gold Chloride
« Reply #36 on: September 21, 2016, 08:23:40 PM »
Hi,
I always wanted to make my one Gold chloride.Today all the equipment is here so I started. I made Aqua regia and dissolved 1 gram of gold. Then added extra HCL and boiled it to boil away any remaining HNO3. After that I started the evaporation process. Because gold will perticipate if evaporation temperature above 120C is used, I put it in a "ben marie" (I put my baker in a bowl with water) so the temperature will go not pass 100C. now after some time there is a sticky redish liquid in the bottom..(see the picture). This as I know is HAUCL4. If I put water till 100 ml would it be good for making colloidal gold? When you state gold cloride at the receipt you mean HAuCl4 in water or AuCl3?

Offline kephra

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Re: Making Gold Chloride
« Reply #37 on: September 21, 2016, 08:35:06 PM »
It doesn't matter whether you use AuCl3 or HAuCl4 as long as the pH is raised above 7 so the reducing agent can work.
There is the unknown and the unknowable.  It's a wise man who knows the difference.

anax

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Re: Making Gold Chloride
« Reply #38 on: September 21, 2016, 09:59:31 PM »
I have not seen a gold chloride solution myself . Please measure the PH of the gold chloride you have. I will compare it to my solution's PH when I will add water and make it 100ml. If mine has lower PH that means more boiling... Thanks

Offline Neofizz

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Re: Making Gold Chloride
« Reply #39 on: September 21, 2016, 10:13:45 PM »
Here is a video link from that might help you get a good visual.

https://www.youtube.com/watch?v=XoqU1GfIOkI
"Be kinder than necessary, for everyone you meet is fighting some kind of battle."

anax

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Re: Making Gold Chloride
« Reply #40 on: September 22, 2016, 09:45:02 AM »
Now I am trying to boil dry my HAuCl4 so I got yellow crystals...But after boiling it for a lot time, it does not form crystals.It remains in that red-orange sticky form.. Any suggestions?( I do not want to overcome 120C because gold perticipates)

Offline Neofizz

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Re: Making Gold Chloride
« Reply #41 on: September 22, 2016, 07:43:44 PM »
I don't have the means to measure the pH of mine. I didn't boil mine down as far as yours though. I tested mine by doing appropriate dilutions and making a cup (250mls) of colloidal gold with it. If it doesn't become crystal clear ruby red by the time it boils in the microwave then it still has too much acid.
"Be kinder than necessary, for everyone you meet is fighting some kind of battle."

anax

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Re: Making Gold Chloride
« Reply #42 on: September 22, 2016, 09:43:13 PM »
So after dissolving gold in aqua regia you add more HCL to remove HNo3 and then you used it? Or after removing HNo3 you add water and boiled it some times more?

Offline Neofizz

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Re: Making Gold Chloride
« Reply #43 on: September 28, 2016, 12:50:32 AM »
When I did it I wanted to dissolve 1 gram from a larger bar.

I ended up using 0.95mls of 70% nitric acid along with HCL in excess (4mls). This way I could ensure that all the nitric acid would get used up in the reaction and I'd end up with my gold bar weighting 1 gram less.

In the end all I was doing was adding 25mls of water and boiling it down to a few mls, but not as much as you boiled yours, then repeating that process 4-5 times.

All the liquids involved are made of gasses that evolve away when boiling. Adding distilled water and boiling it down effectively dilutes the unwanted acids. It's just a matter of how many times is enough, which seems to be a bit of a guess.

Mine works but could have been boiled more and I'll remember that when I make the next batch. For now I'm compensating by adding a bit more sodium carbonate solution when I make the colloidal gold with it. It works without this addition but takes longer for the colour to form.


"Be kinder than necessary, for everyone you meet is fighting some kind of battle."

MagnumOpus

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Re: Making Gold Chloride
« Reply #44 on: November 29, 2016, 05:41:50 AM »
Hey folks,

First off I just want to say that I'm loving this forum, great bunch here and very knowledgeable!  :)

I'm making AuCl (or HAuCl4?) with the following method:

100 mg of 24k gold leaf was placed in a graduated cylinder. To this I added ~3 mL 31.45% HCl and ~1 mL 35% H2O2 (food grade). I just used those amounts and ratio off the top of my head, probably way too much acid to dissolve this much gold. To my surprise the gold leaf dissolved rapidly in about 10 mins without any heat added. Gold leaf is extremely fine so I guess it doesn't need much coaxing.

I plan to add 50ml distilled water to this and boil it down a few times to remove the excess HCl. The question is, should I keep adding measured amounts of gold leaf until the HCl/H2O2 solution stops eating it up before adding water and boiling it down or can I just use the salts obtained after removing most of the acid to make a 1% solution? I'm just worried about excess HCl in the final product. It will just be salt once I boil out the majority of the HCl though right?

To get a 1% solution I just add 10mL of H2O to the semi dry salt.  0.1g/10mL=0.01 or 1% and 1ml of this would contain 10mg of Au.