Cadmium: reactions of elements

Reaction of cadmium with air

Cadmium metal burns in air to form cadmium(II) oxide. This material is coloured variously, depending upon how it was made.

2Cd(s) + O2(g) → 2CdO(s)

Reaction of cadmium with water

Cadmium metal does not react with water.

Reaction of cadmium with the halogens

Cadmium difluoride, cadmium(II) difluoride, CdF2, cadmium dibromide, cadmium(II) dibromide, CdBr2, and cadmium diiodide, cadmium(II) diiodide, CdI2, are formed in the reactions of cadmium metal and fluorine, F2, bromine, Br2, or iodine, I2.

Cd(s) + F2(g) → CdF2(s) [white]

Cd(s) + Br2(g) → CdBr2(s) [pale yellow]

Cd(s) + I2(g) → CdI2(s) [white]

Reaction of cadmium with acids

Cadmium metal dissolves slowly in dilute sulphuric acid to form solutions containing the aquated Cd(II) ion together with hydrogen gas, H2. In practice, the Cd(II) is present as the complex ion [Cd(OH2)6]2+.

Cd(s) + H2SO4(aq) → Cd2+(aq) + SO42-(aq) + H2(g)

The reacts of cadmium with oxidizing acids such as nitric acid, HNO3, are complex and depend upon precise conditions.

Reaction of cadmium with bases

Cadmium metal does not dissolve in aqueous alkalis such as potassium hydroxide, KOH.

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