1. Could aqueous ammonia be used instead of hot water to separate lead ion from the mixed chloride precipitate? Explain.
2. The test for Ag+ is to add HNO3 and see if a precipitate of AgCl forms. Where does the Cl- come from? Why does adding HNO3 make AgCl precipitate? Write an appropriate balanced reaction.
3. In the step where Ag+ and Hg2+ are being separated by addition of 6 M NH3, a student obtains a black precipitate and a clear, colorless supernatant for both the known and the unknown. The student concludes that both cations are present because the results are the same. Assess the student’s conclusions for their accuracy, being sure to explain why the student is or is not correct for each cation.
