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Chemical Equalibrium Constant

  1. Mar 16, 2017 #1
    1. The problem statement, all variables and given/known data
    Fe2+and Cr2O72- react as follows: 6Fe2+ + Cr2O7 2− + 14H + >>> 6Fe3+ + 2Cr3+ + 7H2O.

    The equilibrium constant for the reaction is 1×10^57. Calculate the equilibrium concentrations

    of the iron and chromium species if 10 mL each of 0.02M K2Cr2O7 in 1.14M HCl and 0.12M FeSO4

    in 1.14M HCl are reacted.

    2. Relevant equations

    3. The attempt at a solution
    https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/97/97696-2f7ec586395970f64d734682baf6f166.jpg [Broken]

    This is the solution provided . I still don't understand as Cr3+ is 0.02M in the equation as the question give is K2Cr2O7 is 0.02M > does it mean 0.02M of Cr2O72- ??? Same goes to iron .

    Attached Files:

    Last edited by a moderator: May 8, 2017
  2. jcsd
  3. Mar 16, 2017 #2


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    Staff: Mentor

    Elaborate please, I have no idea what you mean.

    Chances are you are forgetting about dilution, but that's just a wild guess.
  4. Mar 16, 2017 #3


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    Science Advisor

    I think there is a mistake in the text; when it says "At equilibrium 0.02 mol/L Cr2O72- has reacted..." that should be 0.01 mol/L Cr2O72-. Is that the problem? I think the expression here is unclear. But then you say "same goes to iron". Are you just forgetting about dilution, as Borek suggests?
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