Is it possible to dissolve gold and make it pure if so what chemicals do you use?
- pisgahchemistLv 78 months ago
It is possible to "dissolve" gold metal, but it won't be "pure", not in the sense that it will form a complex ion in solution after reacting with aqua regia.
As mentioned, gold dissolves in aqua regia, a mixture of hydrochloric and nitric acids. Gold is oxidized and the nitrogen in nitric acid is reduced. But nitric acid by itself won't do the trick (as it does with silver and copper) because the gold is oxidized to solid Au2O3 which provides a protective barrier to further oxidation. The presence of chloride ion prevents that, by forming a complex ion AuCl4^- in much the same way that aluminum metal reacts with acids when Cl- ion is present.
The overall unbalanced equation:
Au(s) + HNO3(aq) + HCl(aq) --> HAuCl4(aq) + NO2(g) + H2O(l)
The unbalanced redox reaction:
Au(s) + NO3^- --> Au3+ + NO2 + H2O
Au(s) --> Au^3+ + 3e- ................... ................. oxidation half-reaction
3(2H+ + NO3^- + 1e- --> NO2(g) + H2O) ....... reduction half-reaction
------------------ -------------------- ------------------------
Au + 6H+ + 3NO3^- --> Au3+ + 3NO2(g) + 3H2O
Formation of complex: (not redox)
Au^3+ + 4Cl- --> AuCl4^-
HAuCl4 is a strong acid and completely ionizes. Therefore, it exists as H+ ions and AuCl4^- ions.
Au(s) + 3HNO3(aq) + 4HCl(aq) --> HAuCl4(aq) + 3NO2(g) + 3H2O(l)
- BiffLv 78 months ago
Aqua regia, a fuming mixture of concentrated nitric and hydrochloric acids, dissolves gold but it isn't stuff to use without a fume cupboard, without experience of handling corrosive chemicals or without wearing the safety equipment, particularly goggles, the acid manufacturers' safety data information require.Source(s): https://en.wikipedia.org/wiki/Aqua_regia
- Roger the MoleLv 78 months ago
- What do you think of the answers? You can sign in to give your opinion on the answer.
- alLv 58 months ago
"regal water" or "king's water") is a mixture of nitric acid and hydrochloric acid, optimally in a molar ratio of 1:3. Aqua regia is a yellow-orange (sometimes red) fuming liquid, so named by alchemists because it can dissolve the noble metals gold and platinum, though not all metals.