Entropy and Equilibrium Constant

[Soaring Crane]

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.

[siddharth]

Your approach to solve this problem looks right.


46 kJ = 4.6E3 J

That looks like a mathematical error.