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-   -   Dissociation of HF (https://www.askmehelpdesk.com/showthread.php?t=463443)

  • Apr 8, 2010, 12:13 PM
    Killerkobrakai
    dissociation of HF
    I am unsure as to how to obtain the correct answer

    Calculate [H+] and the % dissociation of HF in a solution containing 1.0 M HF (Ka = 7.2x10^-4) and 1.0 M NaF?
    do I make an ICE table with:

    HF + NaOH <-> H2O + NaF
    1 1
    -x +x

    It just doesn't make sense to me. I think I have the wrong initial equation. I know how to do % dissociation. I just can't get started. Any help please2
  • Apr 9, 2010, 05:28 AM
    joinforfun8909

    NaF is a strong electrolyte. So assume that its dissocation goes to completion and you'll have [F-]= 1 M.

    The equlibrium equation is
    HF <-> H+ + F-
    I 1.0 0 1.0
    C -x x +x
    E 1-x x 1+x

    Then use definition of K.
    K = (1+x)(x)/(1-x).
    Solve for x. That's your answer !

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