Question

Once contaminated, polluted water sources must be treated or they represent a hazard to local residents. We have mentioned before that lead (Pb2+) ions are a particularly dangerous pollutant. How do we remove ions that we can't even see? Here our understanding of solubility can help. If we add an anion that forms an insoluble salt with Pb2+ ions, we could filter off the solid that forms and remove much of the lead contamination. Use what you know to help. Select all of the following salts, that when added to our lead contaminated water could form an insoluble lead salt. Hint: use the solubility rules and decide which of these salts would provide an anion that would form an insoluble salt with Pb2+. NaOH Na, so MgCl2 ELIC,H,O, E KNO, Ca(ClO4)2 While mixing Pb<2+ ions with Br ions can form an insoluble salt (PbBr2), just mixing a solution of Pb(NO3)2 and NaBr does not guarantee that a ppt will form? There must be enough of each ion present for est e d Think about it this way: it is possible to create a dollar of US currency

Answer 1

Out of the Six Anions, Pb(OH)₂, PbCl_​​​2 and PbSO_​​​4 are Insoluble in Water. Thus, Addition of NaOH, MgCl_​​​2 and Na₂SO_​​4 will precipitate Pb^{​​​​​2+}.

But, the best Reagent among these three is NaOH, since the Solubility Product of Pb(OH)₂ is the lowest, it is of the order of ~10^-20.