Chemical reactions

Reaction of cerium with acids

Cerium dissolves readily in dilute sulphuric acid forming Ce(III) ions and hydrogen gas, H2.

2 Ce(s) + 3 H2SO4(aq) 2 Ce3+(aq) + 3 SO42−(aq) + 3 H2(g)

Reaction of cerium with air

Cerium tarnishes slowly in air forming cerium(IV)oxide, CeO2. Cerium metal also burns readily.

Ce(s) + O2(g) CeO2(s)

Reaction of cerium with the halogens

Cerium reacts with all the halogens forming cerium(III)halides.

2 Ce(s) + 3 F2(g) 2 CeF3(s) [white]
2 Ce(s) + 3 Cl2(g) 2 CeCl3(s) [white]
2 Ce(s) + 3 Br2(g) 2 CeBr3(s) [white]
2 Ce(s) + 3 I2(g) 2 CeI3(s) [yellow]

Reaction of cerium with hydrogen peroxide

Cerium(III) is precipitated by peroxide under alkaline conditions

Ce(OH)3(s) + HO2(aq) Ce(O2)OH(s) [reddish-brown]

The peroxohydroxide is converted to Ce(OH)4 by heat:

Ce(O2)OH(s) + 3 H2O(l) + OH(aq) Ce(OH)4(s) [yellow] + HO2(aq)

Under acidic conditions Ce(III) can only be oxidized by strong oxidizers like PbO2. Usually nitric acid is used, giving yellow nitrate complexes ([Ce(NO3)6]2−).

Cerium(IV) is reduced by hydrogen peroxide under acidic conditions

2 [Ce(NO3)6]2−(aq) + H2O2(aq) 2 [Ce(NO3)6]3−(aq) + O2(g) + 2 H+(aq)

Reaction of cerium with hydroxide ions

Cerium is precipitated by hydroxide ions.

Ce3+(aq) + 3 OH(aq) Ce(OH)3(s) [white]
Ce4+(aq) + 4 OH(aq) Ce(OH)4(s) [yellow]

Reaction of cerium with oxalates

Cerium is precipitated by ammonium oxalate under acidic conditions

Ce3+(aq) + NH4+(aq) + 2 HC2O4(aq) NH4Ce(C2O4)2(s) [white]

Reaction of cerium with phosphates

Cerium is precipitated by phosphate with acetic acid

Ce3+(aq) + H2(PO)4(aq) Ce(PO)4(s) [white] + 2 H+(aq)

Reaction of cerium with water

Cerium reacts slowly with cold water and quickly with hot water forming cerium hydroxide, Ce(OH)3, and hydrogen gas, H2.

2 Ce(s) + 6 H2O(l) 2 Ce(OH)3(s) + 3 H2(g)