Unsaturated and saturated

Question

I was wondering if anyone can help with Saturated and Unsaturated solutions Huh. When can I tell if a solution is Saturated and Unsaturated? I was doing this problem for my class and I can't figure it out:

The equation at the bottom as a equilibria to the right:

Zn(OH)2 (s) <-> Zn2 (aq) 2OH- (aq)

I was down to two answer choice that had the correct Ksp expression but had a hard time telling if it was in a saturated solution of Zn(OH)2 or unsaturated solution of Zn(OH)2. The correct answer was "Ksp in saturated solution of Zn(OH)2". I know the Ksp is only affected by temps and that common ion affects lowers Ksp, but completely clueless on Saturated and Unsaturated.

Answer 1

[Answer:

Because you know there is an equilibrium between solid Zn(OH)2 and your Zn^2+ and OH- ions, that must mean that no more solid Zn(OH)2 can dissolve into its ions (though you have to remember that even at equilibrium, there are still equal amounts of solid dissolving but an equal amount of ions turning into solid, leading to no changes on the macroscopic level though things are still happening at the microscopic level).  Therefore, because a saturated solution is defined as a solution which cannot dissolve any more solid, this is what we have.

The Ksp you would find is

Ksp = [Zn^2+][OH-]² and which you now know to be a saturated solution.]

Answer 2

A solution is saturated if you cannot dissolve any more of the chemical in water.    Unsaturated would then mean that you can dissolve more in the water.