Chemical reactions

Reaction of gold with acids

Gold does not dissolve in nitric acid, HNO3 [4].

Au(s) + HNO3(aq)

Gold dissolves in aqua regia, a mixture of hydrochloric acid, HCl, and concentrated nitric acid, HNO3, in a 3:1 ratio [4]:

Au(s) + 6 H+(aq) + 3 NO3(aq) + 4 Cl(aq) [AuCl4](aq) + 3 NO2(g) + 3 H2O(l)

Reaction of gold with air

Gold does not react with air under normal conditions.

Reaction of gold with bases

Gold does not react with aqueous bases.

Reaction of gold with cyanide

Gold forms complexes with cyanide [4].

4 Au(s) + 8 CN(aq) + 2 H2O(l) + O2(g) 4 [Au(CN)2](aq) + 4 OH(aq)

The complex is used for extration of silver in solid form [4].

Reaction of gold with halogens

Gold metal reacts with chlorine, Cl2, and bromine, Br2, forming the trihalides gold(III) chloride, AuCl3, and gold(III) bromide, AuBr3, respectively.

2 Au(s) + 3 Cl2(g) 2 AuCl3(s)
2 Au(s) + 3 Br2(g) 2 AuBr3(s)

Gold reacts with iodine, I2, forming the monohalide gold(I) iodide, AuI.

2 Au(s) + I2(g) 2 AuI(s)

Reaction of gold with hydrogen

Gold does not react with hydrogen, but hydrogen can be dissolved in gold [4].

Reaction of gold with water

Gold does not react with water.