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
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.
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
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.)
balanced oxidation half reaction.
balanced reduction half reaction
8. write the full