6K.3 D)

[briannam_1F]

How is Cl2 acting as both a oxidizing and reducing agent? Also, why does the half-reaction Cl2(g) --> 2Cl-, where did the Cl- come from?

[Goyama_2A]

to your first question, I believe that Cl is acting as both a reducing and oxidizing agent because one of the Cls is giving an electron while the other is accepting that electron.
to your second question, I think someone told me that the Cl2 reactant is a typo and that it should be 2Cl

[William Francis 2E]

The Cl- comes from the reduction of Chlorine gas (Cl₂+2e^--->2Cl^-). After you find the oxidation reaction of chlorine, you can determine that it must also be reduced since it is the sole reactant listed. Although Cl^- is not in the skeletal equation given, it must be present in the final balanced equation you write as a reduced form of chlorine from Cl₂ just as the chlorine in HClO (with an oxidation number of positive one) is an oxidized form of chlorine from Cl₂ (here, the chlorine has an oxidation number of zero).