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Topic: Equilibrium constant from Ksp and Kf  (Read 26052 times)

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Offline KidA

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Equilibrium constant from Ksp and Kf
« on: April 09, 2008, 07:58:54 PM »
Looking for help with a homework problem:
The solubility product for a sparingly soluble transition metal salt, M2X, equals 5.90E-21. The formation constant for the formation of the hexaammine complex of the transition metal ion [M(NH3)6]2+ in aqueous solution equals 6.70E+10. Calculate the value of the equilibrium constant for the overall solution process for the sparingly soluble salt in the presence of ammonia.

Here's what I've done:

Knet = Ksp x Kf so....

Knet = (5.90E-21) x (6.70E10) = 3.953E-10 but the computer tells me this answer is incorrect. I also entered 3.95E-10 thinking the sig figs might be what's wrong, but it still came back incorrect. Any help would be greatly appreciated.

Offline Borek

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Re: Equilibrium constant from Ksp and Kf
« Reply #1 on: April 10, 2008, 03:19:58 AM »
Start with the balanced reaction equation and write formula for the reaction equilibrium. Then write formula for Ksp x Kf (expressed in terms of concentrations) and compare - you will see if your approach gives correct result or not.
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