with chem lab (starts at 8 am today!!!). Added NaF to 3 separate solutions containing Ca2 Mg(OH2)6 2 and Al(OH2)6 3 . Found the calcium & magnesium precipitated and aluminum apparently did not. (so concluded CaF2 and MgF2 were much less soluble).So the point of that acc. to my lab was to figure a method for testing Mg2 in the presence of Al3 . The question is what ion would interfere with this test and why? And how can this interference be circumvented?