Question: if 10.0 mg of Mg(OH)2 is placed in 100 ml of pure water, will all of the sample dissolve before equilibrium can become established, or will some sample remain undissolved?

Question

i got the Molarity of Mg(OH)2 to be .00172 M. Where does that exactly go into the ice table. the equation is Mg(OH)2 -> Mg + 2OH. How do i set up the ice table. Will the sample remain undisolved?

Answer 1

M = moles/L
So if the M = 0.00172, then the moles in a liter will be 0.00172. Since the problem tells you it is in 100 mL, then 1/10 that will be the moles that will dissolve in 0.100 L. To convert that to grams, moles = g/molar mass, then convert grams to mg.

Answer 2

Don't you want to set up an ice table and find X so you can determine if the sample dissolves or if the sample remaines undissolved?

Answer 3

I don't think an ICE table is needed. You have the solubility at 0.00172 M so 1.72 x 10^-3 M is the # moles in 1 L, then 1.72 x 10^-4 is the # moles in 0.100 L, and grams = moles x molar mass.