Reaction of holmium with acids
Holmium dissolves readily in dilute sulphuric acid, forming Ho(III) ions and hydrogen gas, H2. The yellow color of the solution has been suggested to be mostly [Ho(H2O)9]3+
2 Ho(s) + 3 H2SO4(aq) 2 Ho3+(aq) + 3 SO42−(aq) + 3 H2(g)
Reaction of holmium with air
Holmium reacts slowly with O2 at room temperature, and burns readily, forming holmium(III) oxide, Ho2O3.
4 Ho(s) + 3 O2(g) 2 Ho2O3(s)
Reaction of holmium with halogens
Holmium reacts with all the halogens, forming the corresponding holmium(III) halides.
2 Ho(s) + 3 F2(g) 2 HoF3(s) [pink]
2 Ho(s) + 3 Cl2(g) 2 HoCl3(s) [yellow]
2 Ho(s) + 3 Br2(g) 2 HoBr3(s) [yellow]
2 Ho(s) + 3 I2(g) 2 HoI3(s) [yellow]
Reaction of holmium with water
Holmium reacts slowly with cold water, forming holmium hydroxide, Ho(OH)3, and hydrogen gas (H2).
2 Ho(s) + 6 H2O(g) 2 Ho(OH)3(aq) + 3 H2(g)