# sulfur dioxide gas and potassium permanganate

**Question description**

Sulfur dioxide gas (SO2) is bubbled through a solution of acidified potassium permanganate (KMnO4). An oxidation-reduction reaction occurs. The unbalanced equation for this reaction is:

MnO4– + SO2 Mn2+ + SO42–

A student wrote the two following half-equations:

Equation One MnO4– + 8H+ + 5e– Mn2+ + 4H2O

Equation Two SO2 + 4H+ + 2e– SO42– + 2H2O

It is **not **possible
to combine these two half-equations as the student had written **Equation Two **incorrectly.

1. Describe the
mistake that was made in **Equation Two**.

2.Write **Equation
Two **correctly.

3. Discuss, in terms
of oxidation-reduction principles, electron transfer and charge, why **Equation
One **and the **original Equation Two **cannot be combined into an overall
balanced equation.

4. Hydrogen peroxide is added to a solution of potassium bromide. You may use the resource tables given at the end of this assignment to help you answer the following questions. Identify which substance is being reduced. Use oxidation numbers and the transfer of electrons to justify your choice.

5. Describe what you would expect to observe for
this reaction. Link all observations
to the species concerned. (Tip: remember
to describe both reactants *and *products.)

6. Write the balanced oxidation half reaction.

7. Write the balanced reduction half reaction

8. write the full balanced equation.

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