Cerium: reactions of elements
Reaction of cerium with air
Cerium metal tarnishes slowly in air and burns readily to form cerium (IV) oxide, CeO2.
Ce + O2 → CeO2
Reaction of cerium with water
The silvery white metal cerium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form cerium hydroxide, Ce(OH)3, and hydrogen gas (H2).
2Ce(s) + 6H2O(g) → 2Ce(OH)3(aq) + 3H2(g)
Reaction of cerium with the halogens
Cerium metal reacts with all the halogens to form cerium(III) halides. So, it reacts with fluorine, F2, chlorine, Cl2, bromine, I2, and iodine, I2, to form respectively cerium(III) bromide, CeF3, cerium(III) chloride, CeCl3, cerium(III) bromide, CeBr3, and cerium(III) iodide, CeI3.
2Ce(s) + 3F2(g) → 2CeF3(s) [white]
2Ce(s) + 3Cl2(g) → 2CeCl3(s) [white]
2Ce(s) + 3Br2(g) → 2CeBr3(s) [white]
2Ce(s) + 3I2(g) → 2CeI3(s) [yellow]
Reaction of cerium with acids
Cerium metal dissolves readily in dilute sulphuric acid to form solutions containing the colourless aquated Ce(III) ion together with hydrogen gas, H2. It is quite likely that Ce3+(aq) exists as largely the complex ion [Ce(OH2)9]3+
2Ce(s) + 3H2SO4(aq) → 2Ce3+(aq) + 3SO42-(aq) + 3H2(g)