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Equilibrium Position - Effect of Dilution

  1. Nov 9, 2007 #1
    Iodine is sparingly soluble in pure water. However, it does `dissolve' in solutions containing excess iodide ion because of the following reaction:

    I-(aq) + I2(aq) I3-(aq) K = 710 L/mol
    For each of the following cases calculate the equilbrium ratio of [I3-] to [I2]:

    2.00×10-2 mol of I2 is added to 1.00 L of 2.00×10-1 M KI solution.


    I did this question using the ICE table and got the RIGHT answer of

    1.28×10^2

    but now the SECOND part asked.. same thing but


    The solution above is diluted to 5.50 L.


    How do i approach this?
     
  2. jcsd
  3. Nov 9, 2007 #2
    nevermind i got it :)
     
  4. Nov 9, 2007 #3
    did you re-use the value you found?
     
  5. Nov 9, 2007 #4
    not really, i just made did the following

    C1V1=C2V2
    (2.00×10-1 M)(1.00 L) = C2(5.50L)

    solved for c2 and then

    2.00×10-2 mol of I2 is added to 5.50 L of C2 KI solution.

    then again did ICE table and solved at equilibrium.. then did the same thing as part a to find ratio of I3 to I2 at equilibrium
     
  6. Nov 10, 2007 #5
    Same question

    I have the same question but with different numbers
    can you show me how to solve it

    8.00×10-2 mol of I2 is added to 1.00 L of 8.00×10-1 M KI solution.

    The solution above is diluted to 13.00 L.
     
  7. Nov 10, 2007 #6
    [tex]M_{1} \times V_{1} = M_{2} \times V_{2}[/tex]

    solve for final Molarity
     
  8. Nov 10, 2007 #7
    yea just solve for molarity first


    (8.00x10^-1)(1.00L) = (c2)(13.00)

    solve for c2 now ur new question is

    8.00×10-2 mol of I2 is added to 13.00 L of c2 M KI solution.



    make Ice table now so u have
    ..........I-(aq)........I2(aq)...........I3-(aq)
    I.......0.08/13.......c2.................0
    C.........-x.............-x................x
    E

    x
    --------------------- = k(watever k value ur given)
    ((0.08/13)-x)((c2) - x)

    solve for ur x using quadratic formula or if ur lazy find one online and just type in a,b and c values to find x, then plug back in to get
    I3:I2

    I3............x
    -- = --------------
    I2........c2-x
     
    Last edited: Nov 10, 2007
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