Three bottles, each containg white solid powder. Using qualitative analysis design an experiment to determine which elements are present in these bottles?
Tough question, Khoob! You need to dissolve the powders in water, and then design a flowchart that will sort the ions in the different solutions based on their solubility characteristics. Here's a list of solubilities to test for:
Ions in Group I: Ag+, Hg22+, Pb2+-will precipitate in 1 M HCl
Ions in Group II: Bi3+, Cd2+, Cu2+, Hg2+, (Pb2+), Sb3+ and Sb5+, Sn2+ and Sn4+ -will precipitate in 0.1 M H2S solution at pH 0.5
Ions in Group III: Al3+, (Cd2+), Co2+, Cr3+, Fe2+ and Fe3+, Mn2+, Ni2+, Zn2+ - will precipitate in 0.1 M H2S solution at pH 9
Ions in Group IV: Ba2+, Ca2+, K+, Mg2+, Na+, NH4+
Ba2+, Ca2+, and Mg2+ will precipitate in 0.2 M (NH4)2CO3 solution at pH 10
Once you have narrowed down the possibilities for each powder, you could try a flame test to make identifications within the groups.
To test for the anions, there are some indicator based tests you could include at this link.