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Stupid equation solving question

  1. Jan 3, 2004 #1

    Monique

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    [tex]K = \frac{f_F}{1-f_F}[/tex]

    OK, I feel like the stupidest person ever, but if I know K, how do I find fF?

    I even know the answer.. if K = 0.504.. fF will be 0.335.. which is 33.5%, the other fraction is 66.5%, which is 0.504..

    Still can't figure how to solve the formula :(
     
  2. jcsd
  3. Jan 3, 2004 #2
    [tex]\begin{align*}
    K&=\frac{f_F}{1-f_F} \\
    K-Kf_F&=f_F \\
    K&=f_F(1+K) \\
    \frac{K}{1+K}&=f_F
    \end{align*}
    [/tex]
     
  4. Jan 3, 2004 #3

    Monique

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    see, I knew it was stupid

    Thanks!
     
  5. Jan 3, 2004 #4
    k = f/1-f

    k - kf = f.

    k = fk + f = f(1 + k)

    f = k/(1+k)
     
  6. Jan 3, 2004 #5
    oh already solved :wink:


    such easy equations... sigh, noob chemists
     
  7. Jan 3, 2004 #6

    Monique

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    I know, I got to the second part, realized that instead of having 1k and 2f, I had 2k and 2f, after which I panicked and gave up :P

    maybe some sleep would be good, it is already 5.40 am after all, but the nernst equation is making absolutely NO sense! [b(]
     
  8. Jan 3, 2004 #7

    Monique

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    gonna make some coffee..
     
  9. Jan 5, 2004 #8

    uart

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    LOL, it's funny how every now and then that one can get stuck on a really simple problem, like a mental block or something.

    A few weeks ago I was trying to re-arrange an equation, and I knew it had a fairly simple final form (I even knew how it should end), but I just kept getting stuck at one point and couldn't get any further.

    It was quite frustrating and several times I thought about posting it here but each time refrained as I knew the answer must be very simple and was afraid of looking too dumb. Eventually I figured it out, and as expected, it was actually very easy, even though it stumped me for two days!. :)
     
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