In the qualitative analysis scheme, magnesium and nickelprecipitate from solution upon the addition of sodium hydroxide.Once separated from the remaining cations by filtration ordecanting, the solid mixture is acidified and warmed to dissolvemagnesium and nickel cations back into solution. Adding ammoniacreates a buffer solution. (Remember, HCl and NH3 makesfor NH4+ cation.) The buffered solutionshould just be basic (say, pH = 8). Adding sodium hydrogenphosphate (Na2HPO4) precipitates magnesium asMgNH4PO4 (Ksp = 3 x 10-13).
a)Write the dissociation equation andcorresponding Ksp expression
b)Calculate the molar solubility ofthe compound
