Calcium (Ca+2) and Magnesium (Mg+2) ions are both present in seawater [Ca+2] = 0.011M and Mg+2 = 0.059 M. When aqueous sodium hydroxide (NaOH) is gradually added to the seawater, calcium hydroxide (Ca(OH)2) and magnesium hydroxide (Mg(OH)2) precipitate from the solution at different pH values.
a) what is the first compound that precipitates as the pH goes up?
b) when the second compound begins to precipitate, what is the concentration of the first compound?