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Homework Help: Entropy and Equilibrium Constant

  1. Apr 11, 2006 #1
    Calculate Ksp for PbI2 at 25 C based on the following data:
    SPECIES------------deltaG_f kJ/mol
    Pb (2+) (aq) -------(-)24.4
    I- (aq)-------------(-)51.6
    PbI2 (s)------------(-) 173.6



    a. 4 x 10-31
    b. 8 x 10-18
    c. 9 x 10-9
    d. 5 x 10-5

    PbI2 <-> Pb (2+) + 2I-

    Use G_f = sigma prod. - sigma reactants

    [2(-51.6) - 24.4]kJ - [-173.6]kJ

    G_f = 46 kJ = 4.6E3 J

    ln K = -G/RT
    K = e^-(4.6E3/(8.314*298.15 K) = 8.72E-9

    Thanks.
     
  2. jcsd
  3. Apr 11, 2006 #2

    siddharth

    User Avatar
    Homework Helper
    Gold Member

    Your approach to solve this problem looks right.

    That looks like a mathematical error.
     
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