Holmium: reactions of elements
Reaction of holmium with air
Holmium metal tarnishes slowly in air and burns readily to form holmium (III) oxide, Ho2O3.
4Ho + 3O2 → 2Ho2O3
Reaction of holmium with water
The silvery white metal holmium is quite electropositive and reacts slowly with cold water and quite quickly with hot water to form holmium hydroxide, Ho(OH)3, and hydrogen gas (H2).
2Ho(s) + 6H2O(g) → 2Ho(OH)3(aq) + 3H2(g)
Reaction of holmium with the halogens
Holmium metal reacts with all the halogens to form holmium(III) halides. So, it reacts with fluorine, F2, chlorine, Cl2, bromine, I2, and iodine, I2, to form respectively holmium(III) bromide, HoF3, holmium(III) chloride, HoCl3, holmium(III) bromide, HoBr3, and holmium(III) iodide, HoI3.
2Ho(s) + 3F2(g) → 2HoF3(s) [pink]
2Ho(s) + 3Cl2(g) → 2HoCl3(s) [yellow]
2Ho(s) + 3Br2(g) → 2HoBr3(s) [yellow]
2Ho(s) + 3I2(g) → 2HoI3(s) [yellow]
Reaction of holmium with acids
Holmium metal dissolves readily in dilute sulphuric acid to form solutions containing the yellow aquated Ho(III) ion together with hydrogen gas, H2. It is quite likely that Ho3+(aq) exists as largely the complex ion [Ho(OH2)9]3+
2Ho(s) + 3H2SO4(aq) → 2Ho3+(aq) + 3SO42-(aq) + 3H2(g)