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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Timeless Thinker on April 02, 2020, 08:00:47 PM

Title: Precipitation Order Based on Ksp
Post by: Timeless Thinker on April 02, 2020, 08:00:47 PM

Sodium chloride is added slowly to a solution that is 0.010 M in Cu+, Ag+, and Au+. The Ksp values for the chloride salts are 1.9× 10−7, 1.6× 10−10, and 2.0× 10−13, respectively. What will be the order of the precipitation of the metals, first to last? Explain or prove your reasoning.

It's just lowest Ksp precipitates firsts, right?
If so, then the order would be Au+, Ag+, Cu+

Title: Re: Precipitation Order Based on Ksp
Post by: Borek on April 03, 2020, 03:14:14 AM

As a most obvious approximation, for identical initial concentrations of cations (as it is in this case) - yes.

To be sure it won't hurt to check stability constants for Cl^- complexes. I doubt they are high enough though.

Title: Re: Precipitation Order Based on Ksp
Post by: Timeless Thinker on April 03, 2020, 04:42:32 PM

How would I check for that? Is there a formula?

Title: Re: Precipitation Order Based on Ksp
Post by: Borek on April 03, 2020, 05:18:40 PM

If you have to ask it is probably beyond your current chemistry level.