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Homework Help: Redox reaction chem problem

  1. Oct 1, 2008 #1
    H2SO4 (aq) + 2HI (aq) --> SO2 (g) + I2 (s) + 2H2O (l)

    Indicate the oxidizing and reducing agents.
    I started by assigning oxidation numbers to all the atoms:
    S=+6 to +4
    I=-2 to 0

    I think H2SO4 is the reducing agent and 2HI is the oxidizing agent. Is this correct?
  2. jcsd
  3. Oct 2, 2008 #2
    SO4 oxidizes HI to I2. But what is the reducing agent and are my oxidation numbers for the atoms correct?
  4. Oct 2, 2008 #3
    Sulfur gained electrons, and is being oxidized. thus, your reducing agent is H2SO4. I Lost electrons, and thus HI is the oxidizing agent.

    this is assuming your oxidation numbers are correct which if i am not mistaken your'e "I" is -1? "H 1+" "I -1" "HI 0"
  5. Oct 2, 2008 #4


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    Staff: Mentor

    OIL - oxidation is loss

    RIG - reduction is gain.

    You can't assign ON to molecule, only to atoms, thus HI doesn't have ON, just (neutral) charge.

    For that you will need H2+. No such animal.
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