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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: SinkingTako on June 11, 2014, 10:33:12 AM

Title: Any shortcut on finding solubility of complex salts that hydrolyse?
Post by: SinkingTako on June 11, 2014, 10:33:12 AM

Take for example copper phosphate, Cu₃(PO₄)₂. It hydrolyse in water to give like HPO₄^2-, H₂PO₄^-, and a bit of Cu(OH)⁺.

The only simplification I can make is really assume that the main species are HPO₄^2-, PO₄^3-, Cu²⁺ and Cu(OH)⁺, then manipulate the mass charge balance equations, after a bit of ugly and nasty math, find the pH of the solution, and thus solubility.

So are there any tips? Like what kind of simplification can you make, or what specific equations to use? Thanks so much!

Erm not chem buddy, or any software of course... With a good, old scientific calculator:)

And for anyone interested, Ksp Cu₃(PO₄)₂ =1.3 x 10^-37
pKa Cu²⁺ = 8
pKa Phosphoric acid = 2.15, 7.09, 12.32