Question

In a experiment, 1 ml of .01 M KMnO4 plus 6 drops of 6 M H2SO4 are added together with drops of 0.1 M FeSO4 until change occurs. The color changed from purple to a clear solution. What is the oxidizing agent and reducing agent ? The balanced net ionic equation with 1/2 reactions? Thank you.

Answer 1

The balanced reaction is :

     +2                      +7                                          +3                         +2

10 FeSO₄ (aq) + 2 KMnO₄ (aq) + 8 H₂SO₄ (aq) → 5 Fe₂(SO₄)₃ (aq) + 2 MnSO₄ (aq) + K₂SO₄ (aq) + 8 H₂O (l)

Here the oxidation state of Fe increases from +2 to +3, so FeSO₄ acts as reducing agent.

The oxidation state of Mn decreases from +7 to +2 , so KMnO₄ acts as oxidizing agent.

The total molecular equation is :

10 FeSO₄ (aq) + 2 KMnO₄ (aq) + 8 H₂SO₄ (aq) → 5Fe₂(SO₄)₃ (aq) + 2 MnSO₄ (aq) + K₂SO₄ (aq) + 8 H₂O (l)

The total ionic equation is :

10Fe²⁺(aq) + 10SO₄^2-(aq) + 2K⁺(aq) +2MnO₄^-(aq) + 16H⁺(aq) +8SO₄^2-(aq) →

                       10Fe³⁺(aq)+15SO₄^2-(aq) + 2Mn²⁺(aq) + 2SO₄^2- (aq) + 2K⁺(aq) + 2SO₄^2- (aq) + 8 H₂O (l)

Net ionic equation is :

10Fe²⁺(aq) +2MnO₄^-(aq) + 16H⁺(aq) →10Fe³⁺(aq) + SO₄^2-(aq) + 2Mn²⁺(aq) + 8 H₂O (l)

This is the net ionic equation.