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Chem question Please help

  1. Nov 14, 2006 #1
    Hello, I just have a question regarding this problem. Please tell me if its correct.

    I have to identify the substance oxidized, the substance reduced, the oxidizing agent, and the reducing agent.


    For the first one This is what I believe:

    H2O2 = substance oxidized
    H202 = Oxidizing agent
    H2CO = substance reduced
    H2CO = reducing agent

    2nd one I believe its:

    2CrO3 = substance reduced
    2CrO3 = substance oxidized
    6HI = oxidizing agent
    6HI = substance reduced

    I am pretty unsure about these answers, can someone please verify them? Thanks!
  2. jcsd
  3. Nov 14, 2006 #2
    Notice how in the first example, you've named the substance that was oxidized to be the oxidizing agent. In the second example, you named the substance that was reduced to be the oxidizing agent. Not only that, but you said chromium oxide was both reduced and oxidized.
  4. Nov 14, 2006 #3
    oh whoops.

    It was supposed to be:

    2CrO3 = substance oxidized
    2CrO3 = Oxidizing agent
    6HI = substance reduced
    6HI = reducing agent

    See this problem was supposed to be an example to a problem set assigned but the answers were cut off. Trying to understand this problem so i can use it to answer the others. Any help would be greatly apperciated.
  5. Nov 14, 2006 #4
    Remember that a reducing agent reduces, and an oxidizing agent oxidizes. An agent that reduces can not in itself be reduced.

    Draw out each half-reaction (including electron transfer) to determine which substance is oxidized, and vice versa.

    I'd suggest taking a look here:

    If you are still confused, post again after having attempted those questions again.
  6. Nov 14, 2006 #5
    I gave it another try, I think the first one may be right but I found the 2nd one to be harder (but who knows they might both be wrong :frown:)


    H2H02 = Reducing agent,because it is oxidized.
    H2CO = Oxidizing agent because it gains an election.
    H2CO2 = substance oxidized because it gains an electron.
    H20 = Substance reduced ? Not really sure.


    6HI = Reducing agent because it losses hydrogen?
    2CrO3 = Oxidizing agent
    Cr2O3 = Substance oxidized. Lose an electron.
    3H2O = substance reduced
  7. Nov 14, 2006 #6
    Anyone please? I have problem set due tomorrow at 10 AM EST time.. I really need these question verified so i can do the rest. Thanks!
  8. Nov 14, 2006 #7
    [tex] H_{2}CO [/tex] : reducing agent

    [tex] H_{2}O_{2} [/tex]: oxidizing agent

    [tex] 2CrO_{3} [/tex]: oxidizing agent

    [tex] 6HI [/tex]: reducing agent
  9. Nov 15, 2006 #8
    ^Thanks a bunch.

    So would that make

    H2C02 - substance oxidized
    H20 - substance oxidized


    Cr2o3 - substanced oxidized
    3H20 - substanced reduced

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