Gold is readily soluble in aqua regia, or in any other mixture producing nascent chlorine, among such mixtures being solutions of (1) nitrates, chlorides, and acid sulphates—e.g., bisulphate of soda, nitrate of soda, and common salt; (2) chlorides and some sulphates—e.g., ferric sulphate; (3) hydrochloric acid and ...
Gold can be dissolved in a sustainable manner with common household chemicals: iodine solution in ethanol, resembling diluted iodine tincture, green oxidant hydrogen peroxide and 2-mercaptobenzimidazole, a compound used in medicinal applications.
Gold is unaffected by air, water, alkalis and all acids except aqua regia (a mixture of hydrochloric acid and nitric acid) which can dissolve gold.
The researchers have taken that next step and shown that highly concentrated solutions of aluminum chloride and aluminum nitrate can also readily dissolve gold as well as the platinum group noble metals.
Dissolving Gold
Aqua regia is used to dissolve gold. Neither nitric acid or hydrochloric acid can do this alone. Nitric acid will act as the oxidizer and is used to form gold ions (Au3+).
Aqua regia is a mixture of hydrochloric acid and nitric acid in the ration 3:1. It is a very strong acid and can dissolve any metals including noble metals like gold and silver.
The only way gold could truly be destroyed is through nuclear reactions. However, there does exist a way to dissolve gold using “Aqua Regia,” which is a mix of hydrochloric and nitric acids.
Thiosulphate dissolves the fine gold out of ores (the gold that has not recovered by gravity) at similar rates to conventional techniques. It's safe and lowers environmental impacts.
Use Nitric Acid
If you have a circuit board with gold plating, you can remove the gold using nitric acid. The acid will dissolve the metal and leave the non-metallic components of the circuit board intact.
Never use toothpaste, baking soda, or a commercial metal cleaner on gold. If you use these abrasives, you may scratch the gold. Never use bleach. Bleach reacts with gold and will eat away at gold alloys.
We were reminded this earlier in February that many people aren't aware of the damage bleach and chlorine can cause to gold. Both cause a chemical reaction that disintegrates the alloys in the jewelry over time. (Nearly all gold jewelry is alloyed, because pure gold is too soft on its own.)
Thiosulfate is considered to be one of the most promising alternative reagents to cyanide due to its non-toxicity and excellent leaching efficiency.
Thiosulphate is an attractive alternative reagent to cyanide for processing gold ores. It is relatively cheap and non-toxic, forms relatively strong gold and silver complexes, and readily leaches gold ores in ammoniacal solutions, catalysed by Cu(II).
However, gold is readily dissolved in a number of solvents, including oxidizing solutions of hydrochloric acid and dilute solutions of sodium cyanide. Gold readily dissolves in these solvents because of the formation of complex ions that are very stable.
Gold is readily soluble in aqua regia, or in any other mixture producing nascent chlorine, among such mixtures being solutions of (1) nitrates, chlorides, and acid sulphates—e.g., bisulphate of soda, nitrate of soda, and common salt; (2) chlorides and some sulphates—e.g., ferric sulphate; (3) hydrochloric acid and ...
Hint: We know that gold cannot be dissolved in any single acid. This is because of the fact that the gold lies at the bottom of the metal reactivity series. So the gold is a very less reactive metal. We know that most powerful acids like hydrochloric acid and nitric acid alone are not able to dissolve gold.
Gold metal dissolves in aqua regia, a mixture of hydrochloric acid, HCl, and concentrated nitric acid, HNO3, in a 3:1 ratio. The name aqua regia was coined by alchemists because of its ability to dissolve gold - the "king of metals".
The most useful and important vehicle for dissolving gold is aqua regia, (royal water), composed of two parts of hydrochloric (muriatic) acid, and one part of nitric (aquafortis).
Gold is not soluble in sulphuric acid except when nitric acid or some other oxidising agent is present. In this case it is again precipitated on dilution with water. Neither platinum nor palladium are dissolved when these are present in a silver alloy.
However, aqua regia will dissolve pure gold. Platinum and palladium require full strength aqua regia. The reactions may take up to 15-20 minutes and may be accelerated by applying heat. * ALWAYS add acid to water!
Aqua Regia Solution Preparation:
Slowly add the nitric acid to the hydrochloric acid (NEVER the other way around) to form a 3:1 ratio solution of three parts hydrochloric acid, and one part nitric acid. Stirring with a stir bar and plate is recommended.
Cyanide is a substance specified in the Seventh Schedule to the Act. A licence or permit is required for the purchase, sale and use of cyanide from the Department of Health, telephone (08) 9222 6883.