Aqueous Chemistry - Solubility Summary Hints

Calculate the solubility of.....

Here you are being asked to calculate the [ion] concentration in solution in molL-1 you do this by solving for [x] using Ks.
For a 1:2 ratio salt, the concentration of 2mol ion will be 2x.


The concentration of Cl ions in solution is 0.1 molL-1, calculate Ks for a solution of MgCl2.......

Here you are being asked to calculate Ks or IP if the solution is not a saturated solution. To do this you use the ion concentration you have been given.

Calculate Known
Mg2+ + 2Cl-
0.1/2 mol/L 0.1 mol/L

If you are given the conc of the 2 mol [ion] in solution, then the 1 mol [ion] in solution will be 1/2 times that value.

Then plug these values into the expression for Ks.

Ks = [mg2+] [Cl-]2


When two solutions are mixed that have a Common ion ...........

These questions require you to plug calculated [ion] into the IP expression and then compare to Ks to determine if a precipitate is formed.


What is the maximum [ion] need to get a precipitate.......

These questions are asking you to use the Ks expression and Ks value to solve for [x]

Here if the 2mol [ion] is known, you /2 to get the 1mol [ion]. But is the 1 mol [ion] is known then you multiply by 2 to get the 2mol [ion].