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Cell Stoichiometry

  1. Nov 12, 2009 #1
    1. The problem statement, all variables and given/known data

    Determine the mass of sodium deposited at the cathode of a molten NaCl(l) electrolytic cell if 10.0 A flow through the cell for 2.00h.

    2. Relevant equations



    3. The attempt at a solution
    For the mole ratio,
    Na+ +e --> Na
    2Cl- --> Cl2 + 2e
    Should I balance the electron ? 2Na+ +2e --> 2Na
    or I use Na+ +e --> Na
    Thanks
     
  2. jcsd
  3. Nov 13, 2009 #2

    Borek

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    Staff: Mentor

    Na+ + e- -> Na will do.

    Do you know Farady's law of electrolysis? Do you know how to calculate charge given current and time?

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  4. Nov 13, 2009 #3
    Yes.
    But when should I balance the electron?
     
  5. Nov 13, 2009 #4

    Borek

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    Staff: Mentor

    Not sure what you mean - sodium reduction reaction is written is already balanced.

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    methods
     
  6. Nov 14, 2009 #5
    You balance the half equations, Then identify which is oxidised and reduced, then you add the electrons to the specific sides (RHS reduction, LHS oxidisation). but if Na+(aq) + e- --> Na(s).

    Just check your standard reduction potentials chart and you'll see.
     
  7. Nov 15, 2009 #6

    Borek

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    Na+(aq) + e- -> Na(s) - state of matter symbol should be listed in plain text, not subscript nor anything.

    These are of no use here - you are already told what is the reaction that goes on - reduction of sodium.

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    Last edited: Nov 15, 2009
  8. Nov 15, 2009 #7
    The super script was an accident, But I dont see why i cannot use sub script for them?
     
  9. Nov 15, 2009 #8

    Borek

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    See http://www.iupac.org/reports/provisional/abstract05/GreenBook051206_prs.pdf [Broken], General Chemistry section, Other symbols and conventions in chemistry (2.10.1), (vi) States of aggregation.

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    methods
     
    Last edited by a moderator: May 4, 2017
  10. Nov 19, 2009 #9
  11. Nov 19, 2009 #10

    Borek

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    Staff: Mentor

    You don't have to - we are interested only in sodium and we need just sodium half reaction. Balanced - but half reaction only.

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