Ap Chem Precipitation Question #2?

A solution contains the ions Ag+, Pb2+, and Ni2+. Dilute solutions of NaCl, Na2SO4, and Na2S are available to separate the positive ions from each other. In order to effect separation, the solutions should be added in which order? A) Na2SO4, NaCl, Na2S B) Na2SO4, Na2S, NaCl C) Na2S, NaCl, Na2SO4 D) NaCl, Na2S, Na2SO4 E) NaCl, Na2SO4, Na2S

Answer and Explain why! Thanks.

2 Answers

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  • 1 decade ago
    Favorite Answer

    Use the sequence E (NaCl, Na2SO4, then Na2S). Silver is insoluble as a chloride, so it would be removed first, the others (Pb and Ni) are soluble as chlorides(Note; lead chloride is soluble as a hot solution but will ppt when cold), next, PbSO4 is insoluble but NiSO4 is soluble so use Na2SO4 to separate lead from nickel. Lastly, nickel sulfide is insoluble and can be separated and collected.

    Source(s): Gen Chem
  • 1 decade ago

    See the following site for reactivity chart and explanation of why:

    http://dbhs.wvusd.k12.ca.us/webdocs/Equations/Solu...

    (All other solubility tables say that silver sulfate is soluble)

    Add Na2SO4 first...lead (Pb) will ppt

    Add NaCl second...silver (Ag) will ppt

    Add Na2S last to ppt the nickel

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