Vanadium(III) sulfate is the inorganic compound with the formula V2(SO4)3. It is a pale yellow solid that is stable to air, in contrast to most vanadium(III) compounds. It slowly dissolves in water to give the green aquo complex 3+.
The compound is prepared by treating V2O5 in sulfuric acid with elemental sulfur:
- V2O5 + S + 3 H2SO4 → V2(SO4)3 + SO2 + 3 H2O
This transformation is a rare example of a reduction by elemental sulfur.
When heated in vacuum at or slightly below 410 °C, it decomposes into vanadyl sulfate (VOSO4) and SO2. Vanadium(III) sulfate is stable in dry air but upon exposure to moist air for several weeks forms a green hydrate form.
Vanadium(III) sulfate is a reducing agent.