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Oxidizing Agent in 2CuO + C

  1. Feb 28, 2015 #1

    Drakkith

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    1. The problem statement, all variables and given/known data

    Which substance is the oxidizing agent in this reaction? 2CuO + C = 2Cu + CO2

    2. Relevant equations

    2CuO + C = 2Cu + CO2

    3. The attempt at a solution

    According to the online program I'm using for homework, CuO is the oxidizing agent, but I don't understand why. The oxidizing agent is the substance that gained electrons. Cu had an oxidation state of +2 prior to the reaction, and ends up gaining electrons to form neutral Cu. Each oxygen had an oxidation state of -2 prior to the reaction and ends up with -2 after the reaction. Carbon has an oxidation state of zero prior to the reaction and ends up with +4 after the reaction since it is reduced.

    So 4 electrons are taken from carbon and given to 2 copper atoms. Shouldn't Cu be the oxidizing agent here? CuO doesn't even exist after the reaction, so how can it have gained electrons?
     
  2. jcsd
  3. Feb 28, 2015 #2

    Bystander

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    All you want to look at is the reactant, no deeper details such as which metal oxide you're using to oxidize C, or the specific mechanism. Sorting "spectators" like K+ from chemistries of aqueous solutions can be arbitrary, and sorting oxidizer, oxidizing agent, can be equally arbitrary, but the reaction as written involves mixing two black solids and getting a bright metal and a gas as products, one reactant was oxidized, and one reactant was reduced. You can also look at it from the point of view that CuO is a way of identifying a specific oxidized copper compound to use in the reaction reducing copper.
     
  4. Feb 28, 2015 #3

    Drakkith

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    So you're saying that since CuO is a reactant, you can't separate the Cu out of it and say that Cu was the oxidizing agent?
     
  5. Feb 28, 2015 #4

    Bystander

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    Correct.
     
  6. Feb 28, 2015 #5

    Drakkith

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    Thanks Bystander.
     
  7. Feb 28, 2015 #6

    Bystander

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    Anytime. Chemistry can be "arbitrary" at times.
     
  8. Feb 28, 2015 #7

    Drakkith

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    Eh. It's the memorization that's killing me.
     
  9. Feb 28, 2015 #8

    Bystander

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    Been there --- enough rote memory will eventually reach a critical mass in which "contexts" will begin to take shape, and you'll be able to start memorizing exceptions to general rules rather than everything that's presented.
     
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