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Homework Help: Oxidation numbers of Mn

  1. Sep 4, 2009 #1
    determine the oxidation number for Mn in each of the following:
    a) KMnO4
    is the ox # -3

    b) LiMnO2
    is the ox # +1
    c) MnO2
    is the ox # +2
    d)K2 MnCl
    is the ox # +1
    e)Mn2 O7
    is the ox # -10

    I need help ASAP PLEASE!
    Last edited: Sep 4, 2009
  2. jcsd
  3. Sep 4, 2009 #2
    Do you know how to compute oxidation numbers in the first place? All of them are wrong. Also, oxidation numbers must have a +/- sign.
  4. Sep 6, 2009 #3
    to determine the oxidation numbers you need to rewrite the compound using the charge of the atoms. For (a), the charge of K is +1, because K is in an Alkali metal and all Alkali metals are plus 1. The charge of O is -2 -- and you have 4 oxygens. The compound KMnO4 has no charge. So...

    KMnO4 = (+1) + Mn + (-2)(4) = 0

    Do the algebra and Mn = +7
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