Video: Oxidation states of vanadium

Vanadium shows one of the widest range of commonly-accessible oxidation states of the transition metals. Using zinc as a reducing agent:

Zn(s) ® Zn2+(aq) + 2 e-

Pale yellow vanadium(V) (as the dihydrogen vanadate ion) is successively reduced to blue vanadium(IV) (as the vanadyl ion), to green vanadium(III), and finally to violet vanadium(II).

[H2VO4]-(aq) + 4 H+(aq) + e- ® VO2+(aq) + 3 H2O(l)
VO2+(aq) + 2 H+(aq) + e- ® V3+(aq) + H2O(l)
V3+(aq) + e- ® V2+(aq)