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JAMB Chemistry 2011 Question 29

Question 29

Redox Reactions

MnO4−(aq) + Y + 5Fe2+(aq) → Mn2+(aq) + 5Fe3+(aq) + 4H2O(l)
In the equation above, Y is

  1. A.5H+(aq)
  2. B.4H+(aq)
  3. C.10H+(aq)
  4. D.8H+(aq)
Show the answer and explanation

Answer: D (8H+(aq))

Explanation

The 4 O atoms of MnO4− form 4H2O, which needs 8 H atoms, so Y = 8H+. Charges check: −1 + 8 + 10 = +17 = +2 + 15.