Optimizing Solubility: Manipulating [OH-] for Precipitation Control

[dav1d]

Homework Statement

What [OH-] would lower the solubility of Mg(OH)2
to 1.5 x 10-5 mol/L?
Ksp is 1.5 x 10-11 for Mg(OH)2.

Homework Equations

Ksp=products/reactants

The Attempt at a Solution

ICE box method

Mg OH (2) Mg(OH)2
initial: ? and I don't know what to do from here or even if this is the correct method to use.

 

[Borek]

You don't need ICE table here, just check at what OH^- concentration concentration of Mg²⁺ is 1.5x10^-5M.

 

[dav1d]

1.5 x 10^-5 = [Mg(OH)2]/[Mg][OH]

correct?

 

[Borek]

Write formula for K_sp of Mg(OH)₂.

 

[dav1d]

Write formula for K_sp of Mg(OH)₂.

K_sp=products/reactants
=[Mg(OH)2]/[Mg][OH]^2

from the equation Mg+2OH = Mg(OH)2

 

[Borek]

No, you need to reread the book. Or check some other sources.