What is the soluibility product constant Ksp for Cu(OH)2?

Question

The hydroxide ion concentration of a saturated solution of Cu(OH)2 is 8.0 x 10^-7 M.What is the soluibility product constant Ksp for Cu(OH)2?

I am really stuck on this one (and a few more)! But I am unsure of how to even start this one. Thanks for all your help!

Answer 1

Cu(OH)2 (s)  ----->  Cu2+ (aq)  + 2OH1- (aq)

If [OH1-] = 8.0 x 10^-7 M, then

[Cu2+] = 4.0 x 10^-7 M (half as much because 1 mol of Cu2+ is produced when 2 moles of OH1- forms)

Ksp = [Cu2+][OH1-]^2

Ksp = (4.0 x 10^-7) x (8.0 x 10^-7)^2 = 2.6 x 10^-19 (2 sig figs)