gold in aqua regia

I was refining dental gold fillings here, consisting of 75% gold. Not a really spectacular video, but nice to see the king of metals, gold going into solution in aqua regia. People who don't know anything about chemistry would go crazy when seeing their precious metal 'dissappear' :P ! Aqua regia is a 3:1 mixture of concentrated hydrochloric acid and nitric acid respectively, and it fumes and gives of chlorine and nitrogen oxides constantly, therefore it should never be stored. Both of these acids can't do it on their own. Nitric acid acts as the oxidiser, and as soon as Au(III) forms, it is stabilised by the chloride-ions, as the AuCl4(-) ion. Nitric acid also reacts with chloride in such and acidic environment, forming chlorine, NO2 and NOCl, These can act as the oxidiser as well. Be careful, the gasses and fumes (HCl/HNO3) produced from aqua regia itself and durin dissolution are highly toxic. Perform in a very well ventilated area, like outside or in a fume hood.