Gold

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.