Reaction of rhenium with acids
Rhenium does not dissolve in hydrochloric acid (HCl) and hydrofluoric acid (HF). It does dissolve in nitric acid, HNO3, and concentrated sulphuric acid, H2SO4, forming solutions of perrhenic acid, HReO4.
Reaction of rhenium with air
Rhenium reacts slowly with oxygen, O2, tarnishing the surface, under normal conditions. If heated, rhenium is oxidized to Re(VII) oxide:
4 Re(s) + 7 O2(g) 2 Re2O7(s)
Reaction of rhenium with halogens
Rhenium will react with F2 when heated, forming a mixture of rhenium(VI) fluoride and rhenium(VII) fluoride. At 400 °C and under pressure, only rhenium(VII) fluoride is formed.
Re(s) + 3 F2(g) ReF6(s)
2 Re(s) + 7 F2(g) 2 ReF7(s)
Reaction of rhenium with water
Rhenium reacts with water :
Re(s) + 2 H2O(l) ReO2(s) + 4 H+(aq) + 4 e− E° = -0.251 V
Re3+(aq) + 3 H2O(l) ReO3(s) + 6 H+(aq) + 3 e− E° = -0.318 V
Re3+(aq) + 4 H2O(l) ReO42−(aq) + 8 H+(aq) + 3 e− E° = -0.795 V
Re3+(aq) + 4 H2O(l) ReO4−(aq) + 8 H+(aq) + 4 e− E° = -0.422 V