Aqua regia mistake can it be fixed ??

[marcelmorgan]

I was on my third cook down of my aqua regia to prepare it for precipitation. And my solution was nearly ready. I had been monitoring it very closely for two days with temp ect. There was maybe a few hours left to finish and i fell asleep :shock: the aqua regia dried right out in a red bubbled mess . Can the pgms be recovered have i made an irreversible mistake? This is not by far the first time using aqua regia but the first time ive ever done something so stupid and i am having trouble finding literature on what to do if this occurs

 

[Palladium]

Add a little hcl to it and what ever is left should go back into solution.

 

[FrugalRefiner]

If the HCl doesn't put it all back in solution, Hoke mentions it.

(5) EVAPORATING OFF THE EXCESS NITRIC ACID
Here again the steam bath is advised, especially for large quantities
of material. Sometimes this evaporation may go too far, and
brown metallic gold will bake out onto the dish. You can easily
dissolve this baked out gold (without adding any nitric acid) in
this way: cover it with a few drops of full-strength hydrochloric
acid, then slowly add a few drops—not more—of a solution of
sodium chlorate in warm water. A very small amount of this sodium
chlorate solution will do the work; add it a drop at a time,
tilting the dish to wash the dissolved gold into the syrup. Stir
well, as this mixture of chlorate and hydrochloric acid can form an
explosive gas, especially when cold, but if your dish is warm, and
your chlorate solution is warm, and if you work slowly, little if any
of the explosive gas will collect.

Dave

 

[marcelmorgan]

Thank you guys appreciate it? Do you have link for hokes book? So can read it all again and have ready for when i have questions ?

 

[nickvc]

Thank you guys appreciate it? Do you have link for hokes book? So can read it all again and have ready for when i have questions ?

Read the post above and in Frugals signature line there are downloadable copies.

 

[Beetle Juice]

Be careful following hokes book it was written in a different age when risk assessments and environmental constraints were lax. Adding sodium chlorate to a solution of hydrochloric acid at low molarity as hoke suggests will form the explosive gas chlorine dioxides at higher molarity >3 you will form chlorine. If ammonia is present and you add sodium chlorate at neutral pH you will make nitrogen trichloride which appears as an oily orange liquid which is even more unstable. Be careful the Humpry Davy lost fingers due to this.