Aqua regia not forming or reacting?

[Perseus832]

Hi guys.
Just looking for some advice. I have a flask with Three coffee filter paper that has maybe 2-3 grams of gold powder in it. I had poured distilled Water in It half way the flask.
I added small amount of hydrocholric acid and the less amount of nitric acid. It’s all connected to a glass washer bottles with sodium hydroxide for a scrubber.
So I did not notice any reaction from it at all. Stayed a clear color. No orange color forming, neither fumes.
Anyone have idea what I may have did wrong.
Thanks.

 

[Striker33]

I think standard practice is to use HCl as your primary liquid in the flask, then add nitric. No need to add water first.

 

[Perseus832]

I think standard practice is to use HCl as your primary liquid in the flask, then add nitric. No need to add water first.

So it’s not salvageable? Can I add just add more of hydrochloric acid? And then some nitric?
I only had one experience of working with aqua regia a while back. Now I’m doing it with a scrubber setup.
Thanks

 

[Striker33]

It’s definitely salvageable, but one thing you may share is more details on roughly what volume of each solution you put in. I typically take notes on my phone as I am going so if something unexpected happens, I could share with people on the forum. You could also post a photo of your container in its present state to give people a better idea. I have refined using AR about 5 times this year and still new without a lot of experience.

After sharing more details, that will help guide your next steps. You may evaporate down or it could be as simple as adding more HCl, nitric and some heat. I would wait to see what some others recommend as well.

 

[Lino1406]

Supposedly one of the acids is too diluted, or not acid at all.

 

[jamad46]

So I'm sitting watching my green aqua regia filter after adding more gold and hcl and it hit me...I must have way to much hcl and nitric for the small amount of gold material that I am trying to put into solution. Could that be? I think so. I am new at this and did not take into consideration the ratio of gold material to aqua regia chemicals. I did try to keep the hcl and nitric at 3:1 just had to much of both. Sound right?

 

[Striker33]

You only need about 1 mL of nitric acid to dissolve 1 gram of gold. You can search the forum for the reference to the exact number. 3:1 ratio is not the proper technique if you overuse the acids. It’s generally recommended to calculate the nitric acid that you need beforehand, based on the amount of gold, then start with less than that amount and add more slowly until all the gold is dissolved.

 

[jamad46]

Awesome thanks!

 

[Shark]

Green indicates the possibility of copper in your AR as well. Copper and other base metals usually require more nitric to dissolve than gold. Small additions of nitric help avoid over use as well as prevent wasting your often expensive nitric acid.

 

[nickvc]

Your initial problem was you had diluted your acids way too much, had you heated the flask it may well have helped the acids to react with your gold or even evaporated enough water to allow the acids to work.

 

[Perseus832]

It’s definitely salvageable, but one thing you may share is more details on roughly what volume of each solution you put in. I typically take notes on my phone as I am going so if something unexpected happens, I could share with people on the forum. You could also post a photo of your container in its present state to give people a better idea. I have refined using AR about 5 times this year and still new without a lot of experience.

After sharing more details, that will help guide your next steps. You may evaporate down or it could be as simple as adding more HCl, nitric and some heat. I would wait to see what some others recommend as well.

I have it all in a 1000ml round flask and have way filled with water. I filled it will water because it had coffee filters and I thought the small amount of aqua regia wont be able to cover the paper to work on the gold.
Maybe I should just add more hydrochloric acid. I’m not sure.

 

[goldenchild]

Even if the acid wasnt enough to completely cover the filters you would have been ok. The AR will break down the paper into a nice pulp that actually aids when filtering. You also need heat. Try to see if just heating will make the gold react. If it's so diluted to the point where it won't react then you'll have to filter everything away from the gold and start over. Make sure to test the filtered liquid doesn't contain any gold that did manage to react.

As others have said you'll simply want to add HCL to your beaker (preferably enough to cover everything) then you'll add nitric in small increments. With the small amount of gold you're working with you may even want to get a pipette and add the nitric drop wise. Heat should always be used.

 

[Striker33]

Also, I would test the scrubber system with heat and just water before doing it with acids to ensure you have no pressure buildup anywhere.

 

[Perseus832]

Even if the acid wasnt enough to completely cover the filters you would have been ok. The AR will break down the paper into a nice pulp that actually aids when filtering. You also need heat. Try to see if just heating will make the gold react. If it's so diluted to the point where it won't react then you'll have to filter everything away from the gold and start over. Make sure to test the filtered liquid doesn't contain any gold that did manage to react.

As others have said you'll simply want to add HCL to your beaker (preferably enough to cover everything) then you'll add nitric in small increments. With the small amount of gold you're working with you may even want to get a pipette and add the nitric drop wise. Heat should always be used.

I see. I was thinking of just filtering out the liquid and then start over with fresh hydrochloric then add nitric little by little.
Thanks. I also did have a hot plate and heated it a bit but no reaction happened.
How would I Test if the acids Water mix have any reacted gold?salts?