Ques. 1AIPMT 2008
Number of moles of MnO4- required to oxidize one mole of ferrous oxalate completely in acidic medium will be
- 7.5 moles
- 0.2 moles
- 0.6 moles
- 0.4 moles
Answer
(3) 0.6 moles
Solution
Ferrous oxalate is FeC2O4; both ions are oxidised by MnO4- in acidic medium:
Fe2+ Fe3+ + e-
C2O42- 2CO2 + 2e-
So the electrons lost by 1 mol FeC2O4 = 1 + 2 = 3 mol.
MnO4- + 8H+ + 5e- Mn2+ + 4H2O
Thus each mole of MnO4- accepts 5 mol electrons.
Moles of MnO4- = 35 = 0.6 mol
Answer: (3)