identifying oxidizing and reducing agents

[Moselle Stieler 3A]

Hi, I'm still a little confused over identifying these agents in an unbalanced reaction like in the achieve problem from the week 7-8 achieve assignment. The reaction was: Cl2O7(g)+H2O2(aq)⟶ClO−2(aq)+O2(g)
Thanks!

[jennacostello8]

The balanced equation would be Cl2O7(g)+4H2O2(aq)+2OH−(aq)⟶2ClO−2(aq)+4O2(g)+5H2O(l). The reduction part of the equation, chlorine changed from +7 to +3. Next, balance the atoms of each half‑reaction. Balance every element other than oxygen or hydrogen first. Then, use H2O to balance the oxygen atoms. OH- would then have to be added to balance out the additional hydrogen and oxygen atoms. For the oxidizing part of this equation, oxygen changes from -1 to 0. You do the same thing you did to the reduction equation then add both equations together. Hope this helps.

[Damin Rawlins 3B]

To identify the oxidizing and reducing agents, you can look at the changes in the oxidation states of the elements in the reaction. In this problem, chlorine in Cl2O7 has an oxidation state of +7, which is reduced to +3 in ClO-2. Therefore, Cl2O7 is the oxidizing agent. On the other hand, oxygen in H2O2 has an oxidation state of -1, which is oxidized to 0 in O2. Here, we can see that H2O2 is the reducing agent! :)