Question

The experiment that I did in lab consisted of performing a qualitative analysis of group 1 and 2 cations and anions. The first thing that I did was to add 5 drops of 3M HCl, centrifuge it, and to observe whether a precipitate would form. It did and in the flowchart it signified that it was a Group I cation. My question is why do Group I cations form precipitates when mixed with HCl? (in this experiment)

Answer 1

The best answer I can give is by asking a similar question: "Why is the color of an orange that color" or "Why is an apple green?" etc. A more sophisticated answer, but I don't know that it is better, is to say that the crystal lattice forces holding AgCl, Hg2Cl2, and PbCl2 together are stronger than the solvation forces from the dipoles of water; therefore, the lattice bonds are not broken and there is no solution.