Chemical reactions

Reaction of iridium with acids

Iridium metal is resistant to acids, including aqua regia.

Reaction of iridium with air

Iridium react with O2 when heated.

Ir(s) + O2(g) IrO2(s) [black]

Reaction of iridium with halogens

Iridium metal reacts with fluorine forming iridium(VI) fluoride, IrF6, and a minor amount of iridium(III) fluoride, IrF3. Carefully heated, iridium(VI) fluoride will form the yellow tetrameric structure [IrF5]4.

3 Ir(s) + 6 F2(g) IrF6(s) [yellow] + 2 IrF3(s) [black]
IrF6(s) [IrF5]4 [yellow]

Iridium reacts with Cl2, Br2 and I2, under dry conditions, forming the corresponding iridium(III) halides

2 Ir(s) + 3 Cl2(g) 2 IrCl3(s) [red]
2 Ir(s) + 3 Br2(g) 2 IrBr3(s) [red-brown]
2 Ir(s) + 4 I2(g) 2 IrI3(s) [dark brown]

Reaction of iridium with water

Iridium does not react with water under normal conditions.