How to identify unknown solutions?

How to identify unknown solutions?

For my AP Chem lab and we are given 7 solutions labeled 1-7 and we must figure out which of the solutions listed below match the unknown solutions. How would i go about doing this and preparing for the lab?

Given solutions to match with the unknowns:
AgNO3
BaCl2
Cu(NO3)2
CuSO4
Pb(NO3)2
KI
Na2S2O3

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2 Comments for How to identify unknown solutions?

  • 1. Hypothetical Quandry  |  February 15th, 2011 at 8:58 am

    make a chart look for precipitates and bubbling by combining different solutions, also cuso4 is blue so you know that

  • 2. Roland P  |  February 15th, 2011 at 9:10 am

    What an exquisite problem! But you want to be a science person (I’m already one). I haven’t worked out problem out completely but,
    (1) only two of the solutions will be colored because they contain a transition metal (d-d transitions).
    (2) All nitrates are soluble.
    (3) What is the test for sulfate (SO42-)?
    (4) What is the test for iodide (I-); hint: same as for Cl- but ppt is yellow (check)
    (5) The killer: [1]: Thus, silver halides, e.g. AgBr, typical components of photographic emulsions, dissolve upon treatment with aqueous thiosulfate:
    2 S2O32? + AgBr ? [Ag(S2O3)2]3? + Br-
    (but we don’t have Br- do we?)
    I’ve given you a ref for the Ksp of possible ppts.[2] If cmpd is not in the table assume it is soluble.

    “Is there any point to which you would wish to draw my attention?” “To the curious incident of the dog in the night-time.” “The dog did nothing in the night-time.” “That was the curious incident,” remarked Sherlock Holmes.
    Email me if you still can’t work it out.

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