You have been given seven pipets that contain solutions of AgNO3, BaCl2, Cu(NO3)2, CuSO4, Pb(NO3)2, — Qualitative Analysis and Solubility Chemistry Question
Problem Context
You have been given seven pipets that contain solutions of AgNO3, BaCl2, Cu(NO3)2, CuSO4, Pb(NO3)2, KI, and Na2S2O3, though not necessarily in this order. Using the materials provided, devise and carry out an experiment to correctly determine the contents of each pipet.
Give a brief description of your experimental plan.
Model Answer
Students should have constructed some kind of data table that examines combinations of solutions with one another. The various color changes and formed precipitates providing evidence which students must use to form conclusions about each unknown solution.
Record your data and other observations.
Model Answer
Qualitative Evidence: The two copper solutions are blue. To distinguish between both blue solutions of copper sulfate and copper nitrate, the copper (II) sulfate will precipitate with barium but not with copper (II) nitrate; both copper (II) solutions will precipitate with the KI. Copper (II) ions will form a redish-brown precipitate with iodide. Silver nitrate forms white solid silver chloride and darkish silver sulfate. Barium forms insoluble whitish barium sulfate and barium iodide. Nitrates are soluble and will thus not form precipitates in combination with any of the other cations. Lead reacts with iodide to form yellow lead iodide, with chloride to form white lead chloride, and with sulfate to form whitish lead sulfate. Thiosulfate will react with silver to form a darkish precipitate that then dissolves on further addition of thiosulfate.
Based on your observations, write the relevant equations that led to your conclusions.
Conclusions
Pipet Contents Justification
#1
#2
#3
#4
#5
#6
#7
Model Answer
Answers: A = Na2S2O3, B = CuSO4, C = KI, D = AgNO3, E = Cu(NO3)2, F = Pb(NO3)2, G = BaCl2. [Note from coordinator instructions: Na2S2O3 = 1, CuSO4 = 2, KI = 3, AgNO3 = 4, Cu(NO3)2 = 5, Pb(NO3)2 = 6, BaCl2 = 7]