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Ek chemistry 1001#889

Discussion in 'MCAT Study Question Q&A' started by inaccensa, Aug 20, 2011.

  1. inaccensa

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    2NaClO3+SO2+H2SO4--> 2NaHSO4 + 2ClO2
    Which of the foll is/are the reducing agent

    -->NaClO3
    -->SO2
    -->H2SO4
    This was my approach
    Reactants
    For NaClO3; Na is +1, Cl +5, O-2
    SO2; S +4, O -2
    H2SO4; H +1, S +6, O -2
    For the products
    NaHSO4; Na +1, H-1, S +8, O -2
    ClO2; Cl +4, O -2

    Cl is undergoing reduction (NaClO3 is the oxidizing agent)
    So Sulfur is being oxidized, but what is the reducing agent?
     
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  3. PingPongPro

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    h +1
     
  4. dorjiako

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    Oxidizing agents are reduced while reducing agents are oxidized.
    Hence, SO2 is the reducing agent because it was oxidized. This is because oxidation number of sulfur went from +4 in SO2 (because oxygen is -2x2 =-4) to +6 (oxidation state of sulfur in both NaHSo4 and H2S04 is 6).
    On the other hand, NaCLO3 is the oxidizing agent because chlorine was reduced. The oxidation number of Chlorine went from +5(03 = -6, Na = +1, Cl=-6+1=-5) to +4(02 = -2 x 2=-4, Cl=+4)
    Hope this helps.
     
  5. inaccensa

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    Can you please explain the how you calculated the oxidation of sulfur in NaHSO4
     
  6. dorjiako

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    Na = +1, H=+1, O4= -2x4=-8, so far we have two positive and eight negatives, so we need +6 to balance out the charges.
    Formular: +1(Na) + 1(H) +? - 8 = 0
    +1+1+?=8
    8-2=6.
    Good Luck.
     
  7. inaccensa

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    I'm getting confused with sodium and hydrogen. I thought that since Na is a more electropositive element, we assign +1. Hydrogen gets a -1 (ex-NaH) Why is it different here?
     
  8. vayntraubinator

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    (not sure if this is what you're referring to)

    Na is the cation, and HSO4 is the anion. The H is still + with regards to the polyatomic anion
     
  9. Xivilus1231

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    hydrogen can have +1 or -1 oxidation states

    +1 is called hydrogen

    -1 is called hydride

    hydrides are usually found in reducing agents (ex. NAH, LiAlH4, or NaBH4)


    I agree it is confusing, but in this problem hydrogen is +1.
     
  10. inaccensa

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    :thumbup: that is all i was asking. thanks
     

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