Reaction of europium with acids
Europium dissolves readily in dilute sulphuric acid, forming Eu(III) ions and hydrogen gas, H2. The solution is very pale pink and is most likely the complex [Eu(H2O)9]3+.
2 Eu(s) + 3 H2SO4(aq) 2 Eu3+(aq) + 3 SO42−(aq) + 3 H2(g)
Reaction of europium with air
Europium tarnishes slowly in air, and burns readily, forming europium(III) oxide, Eu2O3.
4 Eu(s) + 3 O2(g) 2 Eu2O3(s)
Reaction of europium with halogens
Europium reacts with all the halogens, forming the corresponding europium(III) halides.
2 Eu(s) + 3 F2(g) 2 EuF3(s) [white]
2 Eu(s) + 3 Cl2(g) 2 EuCl3(s) [yellow]
2 Eu(s) + 3 Br2(g) 2 EuBr3(s) [grey]
2 Eu(s) + 3 I2(g) 2 EuI3(s)
Reaction of europium with water
Europium reacts slowly with cold water, and quickly with hot water, forming europium hydroxide, Eu(OH)3, and hydrogen gas (H2).
2 Eu(s) + 6 H2O(g) 2 Eu(OH)3(aq) + 3 H2(g)