Addition of potassium chloride (KCl):
Halides (Cl–, Br–, and I–) are soluble except when paired with Ag+, Pb2+, Cu+, Hg22+
2 KCl + Hg22+ → Hg2Cl2 + 2 K+
Hg2Cl2 → insoluble
Hg22+ → present in the solution
2 KCl + Ba2 + → BaCl2 + 2 K+
BaCl2 → soluble → for next step
2 KCl + Fe2+ → FeCl2 + 2 K+
FeCl2 → soluble → for next step
Addition of potassium sulfate (K2SO4):
A solution contains one or more of the following ions: Hg2 2 + , Ba2 + , and Fe2 + . When potassium chloride is added to the solution, a precipitate forms. The precipitate is filtered off and potassium sulfate is added to the remaining solution, producing no precipitate. When potassium carbonate is added to the remaining solution, a precipitate forms.
Which ions were present in the original solution?
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