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Aqua regia is primarily used to produce chloroauric acid, the electrolyte in the Wohlwill process for refining the highest purity (99.999%) gold. Aqua regia is also used in etching and in specific analytic procedures. It is also used in some laboratories to clean glassware of organic compounds and metal particles.
Fulminating gold – a number of gold based explosives which "fulminate", or detonate easily. – gold hydrazide, formed by adding ammonia to the auric hydroxide. When dry, can explode on concussion. – an unstable gold carbonate formed by precipitation by potash from gold dissolved in aqua regia. Galena – lead(II) sulfide. Lead ore.
Silver was removed by filtering and gold was then recovered by evaporating the liquid and heating the residue. Nitric acid was suitable for separating small quantities of gold from silver and aqua regia used to separate small quantities of silver from gold. Aqua regia acid process is used by refiners of scrap gold used in jewelry manufacturing.
Gold(III) chloride was first prepared in 1666 by Robert Boyle by the reaction of metallic gold and chlorine gas at 180 °C: [1] [6] [7] 2 Au + 3 Cl 2 → Au 2 Cl 6. This method is the most common method of preparing gold(III) chloride. It can also be prepared by reacting gold powder with iodine monochloride: [5] 2 Au + 6 ICl → 2 AuCl 3 + 3 I 2
Chloro(dimethyl sulfide)gold(I) is commercially available. It may be prepared by dissolving gold in aqua regia (to give chloroauric acid), followed by addition of dimethyl sulfide. [2] Alternatively, sodium tetrachloroaurate may be used as the source of gold(III). [3] The bromo analog, Me 2 SAuBr, has also been synthesized by a similar route. [4]
Generally, the preparation of this material involves gold being dissolved in aqua regia, then reacted with a solution of tin(II) chloride. The tin(II) chloride reduces the chloroauric acid from the dissolution of gold in aqua regia to a colloid of elemental gold supported on tin dioxide to give a purple precipitate or coloration.
This method has been used since ancient times. In modern times, additional tests can be done. The trace will react in different ways to specific concentrations of nitric acid or aqua regia, thereby identifying the quality of the gold: 24 karat gold is not affected but 14 karat gold will show chemical activity.
A visualization of the aqua fortis (nitric acid) and aqua regia acid tests on zinc, copper, silver, and gold. Testing for gold with acid capitalizes on gold's status as a noble metal, resistant to corrosion, oxidation, or acid. The procedure includes rubbing the gold-colored item on black stone, leaving a visible mark.