1. The chemistry of vanadium

2. Variable Oxidation States
What type of reaction is it when you switch between oxidation states?
Redox reaction
The metal ions are either oxidised or reduced

3. Vanadium Oxidation State of Vanadium Formula of ion Colour of ion
VO2+(aq)
V3+(aq)
V2+(aq)

4. Vanadium Oxidation State of Vanadium Formula of ion Colour of ion +5
VO2+(aq) +4 +3
V3+(aq) +2
V2+(aq)

5. You need to know the colours and the oxidation states!
Vanadium
Oxidation State of Vanadium
Formula of ion
Colour of ion +5
VO2+(aq)
Yellow +4
Blue +3
V3+(aq)
Green +2
V2+(aq)
Purple
You need to know the colours and the oxidation states!

6. Reducing vanadium from +5 to +2
Ammonium vanadate (V) – NH4VO3
Acidic solution contains VO2+
When zinc is added, reduction begins and there is a gradual colour change.
All are solutions  no precipitates!

7. Reducing vanadium from +5 to +2
Ammonium vanadate (V) – NH4VO3
Acidic solution contains VO2+
When zinc is added, reduction begins and there is a gradual colour change.
All are solutions  no precipitates!

8. Equations
Task:
Use the data to write equations for each reduction equation with zinc of vanadium
(Hint: You will end up with 3 equations)
Recap of redox

9. Equations
1. Yellow to blue Vanadium(V) to vanadium(IV) 2VO2+(aq) +Zn(s) +4H+(aq) → 2VO2+(aq) +Zn2+(aq) +2H2O(l) 2. Blue to green Vanadium(IV) to vanadium(III) 2VO2+(aq) +Zn(s) +4H+(aq) → 2V3+(aq) +Zn2+(aq) +2H2O(l) 3. Green to Purple Vanadium(III) to vanadium(II) 2V3+(aq) +Zn(s) → 2V2+(aq) +Zn2+(aq)

10. Exam question