Reaction of hafnium with acids
Hafnium is resistant to most mineral acids, under cold conditions. Hafnium is dissolved in hydrofluoric acid, HF, presumably forming fluoro complexes.
Reaction of hafnium with air
Hafnium react slowly with O2 at room temperature, passivating the surface. Hafnium can burn, and as powder it is classified as a fire hazard.
Hf(s) + O2(g) HfO2(s)
Reaction of hafnium with bases
Hafnium does not appear to react with bases under normal conditions.
Reaction of hafnium with halogens
Hafnium metal reacts with all the halogens, when heated, forming the corresponding hafnium(IV) halides.
Hf(s) + 2 F2(g) HfF4(s) [white]
Hf(s) + 2 Cl2(g) HfCl4(s) [white]
Hf(s) + 2 Br2(g) HfBr4(s) [white]
Hf(s) + 2 I2(g) HfI4(s) [white]
Reaction of hafnium with water
Hafnium does not react with water under normal conditions.