Question

Using the half- reaction method, balance the redox reaction shown below. (I-)+(Br2) ---> (IO3-)+(Br-)

Step 1. Break the reaction into the two half reactions.
Br2 ==> Br^-
I^- ==> IO3^-

Step 2. I will leave the first one for you to do. The second one is done as follows:
Determine the change in oxidation state of the element changing. In this case, I.
I on the left is -1. On the right is +5.

Step 3. Add electrons to the appropriate side to balance the change in oxidation state.
I^- ==> IO3^- + 6e

Step 4. Determine the charge on each side. The left side is -1; the right side is -7. Add H^+ in acid solution to balance the charge.
I^- ==> IO3^- + 6e + 6H^+

Step 5. Add water to the opposite side to balance the H^+.
I^- + 3H2O ==> IO3^- + 6e + 6H^+
This completes the balancing for this half reaction.

Post your work if you get stuck on finishing.

Answer 1

Iodine doesn't have an oxidation state of -1 in the molecule I-Br because it is a heteronuclear molecule. Br is more electronegative therefore it would have an oxidation state of +1.

Answer 2

Therefore Iodine would have an oxidation state of +1 not Br.