posted by Vic .
Why is sulfur dioxide (SO2) a better reducing agent than carbon dioxide (CO2) or nitrogen dioxide (NO2)?
I really don't know how to answer your question. It's much like asking why the sky is blue, etc. You can look up the reduction potentials of SO2 vs CO2 and NO2 and explain it that way. SO2 is better than CO2 partly because (since a reducing agent is oxidized in the process) SO2 has higher oxidation states available (SO3 for example) and CO2 does not. It isn't usually found with oxidation states above +4. That isn't true for NO2 for NO2 can go to N2O4 or NO3^- and you would need the redox potentials for that. I hope this helps or if you give some context in which your question is asked we may be able to rephrase the answer.
Thanks anyway - it was just a mukltiple choice on my semester exam. :-)