Chemical Properties of Gold

The chemical character of the metal accords with its low electroaffinity, an example being its stability towards the action of strong acids; although boiling, concentrated nitric acid dissolves it to a slight extent. It is also dissolved by selenic acid. The metal is readily brought into solution by the action of powerful oxidizers such as chlorine, and by mixtures in which chlorine is generated. Such mixtures are formed by hydrochloric acid with peroxides, chromic acid, permanganate, or nitric acid, and by hypochlorites with sulphuric acid. Other oxidizing mixtures have a similar effect, examples being solid potassium permanganate and sulphuric acid; the higher oxides and peroxides of manganese with concentrated sulphuric acid, arsenic acid, or phosphoric acid; those of lead, nickel, and chromium with concentrated sulphuric acid or phosphoric acid; and concentrated nitric acid with sulphuric acid. At 160° C. gold is attacked by sulphuryl chloride, SO₂Cl₂, with formation of auric chloride and evolution of sulphur dioxide. It is also attacked by pyrosulphuryl chloride, S₂O₅Cl₂. Aqua regia converts it into aurichloric acid, with evolution of nitric oxide:

Au+HNO₃+4HCl = HAuCl₄+NO+2H₂O.

The metal does not combine directly with oxygen.

Normally, gold does not display radioactivity, neither the metal nor its salts affecting the photographic plate. Cobb states that after exposure to a high-tension discharge between platinum electrodes amorphous gold does not affect a photographic plate, and further alleges that traces of copper are produced in the metal.

Aurous Compounds	Compounds of Bivalent Gold	Auric Compounds
Aurous fluoride, AuF Aurous chloride, AuCl Aurous bromide, AuBr Aurous iodide, AuI Aurous oxide Au2O Aurous sulphide, Au2S Aurous thiosulphate, Au2S2O3,3H2S2O3,H2O Aurous Derivatives of Nitrogen Aurous cyanide, AuCN Potassium aurothiocyanate, KAu(CNS)2 Complex Derivatives of Ammonia and Aurous Halides	Gold dichloride, AuCl2 Gold dibromide, AuBr2 Gold monoxide, AuO Gold monosulphide, AuS Gold monosulphate, AuSO4 Nitride of Bivalent Gold Gold carbide, Au2C2	Auric chloride, AuCl3 Aurichloric Acid, HAuCl4 Sodium aurichloride, NaAuCl4,2H2O Potassium aurichloride, KAuCl4 Ammonium aurichlorides Auric bromide, AuBr3 Potassium auribromide, KAuBr4 Ammonium auribromide, NH4AuBr4 Auric iodide, AuI3 Auri-iodic Acid, HAuI4 Auric iodate Auric hydroxide, AuOOH Auric sulphide, Au2S3 Auric sulphate, Au2(SO4)3 Acid auryl sulphate, AuOHSO4 Auric selenide Auric selenate, Au2(SeO4)3 Auric telluride, Au2Te4 Derivatives of Gold and Nitrogen Auric nitrates Compounds of Gold and Phosphorus Gold phosphides Gold arsenides Auric antimonide, AuSb Auric cyanide, Au(CN)3 Salts of Auricyanic Acid Double Salts of Auric thiocyanate