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O Level Chemistry & IP Chemistry Notes by 10 Year Series Author – Chemistry Specialist

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O Level Chemistry: Redox Reactions

Thought you might find this Redox Reactions question interesting and challenging to solve.
Question by a top secondary school preliminary papers that test you on Oxidation States / Oxidation Numbers.

(Click on Image to have a clearer view)
simplechemconcepts-redox-reaction.jpg

“Whatever you FOCUS on E.X.P.A.N.DS”~ Sean

PS: Check out the “Comments” below for suggested answers.

Related Articles:

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  • O Level Chemistry: Redox Reactions
  • O Level Chemistry – More Questions on Redox
  • O Level Chemistry: Qualitative Analysis / Preparing Salts / Precipitation

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Comments

  1. sean says

    April 16, 2008 at 9:59 am

    Hi Gary,

    Hope all is well with your revision for Mid-Year exams.

    Spot On! Answer is indeed D and your approach towards such Redox question is
    correct.

    Like what Jennifer has mentioned, the stoichiometry of each species does not
    affect the O.S. since the equation is balanced.

    Keep up the good work!

    To your Academic Success in Chemistry
    Sean
    Founder & Master Trainer
    http://www.SimpleChemConcepts.com

  2. sean says

    April 16, 2008 at 9:56 am

    Hi Jennifer,

    Very good attempt indeed. The approach you use is correct.

    Just note that for (A), the O.S. for N should be +4 instead of +3. Check out the
    working again.

    Keep up the good work!

    To your Academic Success in Chemistry,
    Sean
    Founder & Master Trainer
    http://www.SimpleChemConcepts.com

  3. Gary says

    March 21, 2008 at 5:00 pm

    My answer is D too.But i think the OS for N2 at the products in A should be +4 instead of +3

    As Jen said,oxidation state for Nitrogen at the reactants are all +5

    A: The OS for N2 at products is +4 so the change of OS is 1.
    B: The OS for N2 at products is +2 so the change of OS is 3.
    C: The OS for N2 at products is +1 so the change of OS is 4
    D:The OS for N2 at products is -3 so the change of OS is 8

  4. Jen says

    March 21, 2008 at 12:28 pm

    Hello.

    My answer would be D

    For A, B, C, D : initial oxidation state (O.S) of Nitrogen = +5
    irregardless of the coefficient of NO3^-1

    A: final O.S of Nitrogen = +3
    hence, change= +3-(+5) = -2

    B: final O.S of Nitrogen = +2
    hence, change = +2 – (+5) = -3

    C: final O.S of Nitrogen= +1
    hence, change = +1 – (+5) = -4

    D: final O.S of Nitrogen = -3
    hence, change = -3 + – (+5) = -8

Trackbacks

  1. SimpleChemConcepts | O Level Chemistry - More Questions on Redox says:
    February 26, 2010 at 12:35 am

    […] Here is a question that we have discussed before on “Largest Change in Oxidation Numbers”: http://simplechemconcepts.com/chemistry-question-redox-reactions-3/ […]

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