Question

Will Cd(OH)2 precipitate if 10.00 g of Cd(NO3)2(s) (MM = 236.42 g/mol) is added to 0.500 L of a 0.800 M NH3 solution?

Answer 1

mols Cd(NO3)2 = grams/molar mass = ? and M Cd(NO3)2 = mols/L = ?

Next,you will need to calculate (OH^-) from 0.800 M NH3.

Then Qsp = (Cd^2+)(OH^-)^2
Substitute M Cd^2+ and M for OH^- into Qsp. If Qsp>Ksp, there will ppt. If Qsp<Ksp, no ppt.
The idea with Qsp is to see if Ksp is exceeded. It can't be exceeded; i.e., if Qsp>Ksp then a ppt must occur in order to keep (Cd^2+)(OH^-)^2 = Ksp.