Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Identification of group 2 metal salts

  1. Nov 13, 2007 #1
    Hi, I carried out a couple of experiments with unknown group 2 salts; X and Y

    I added dilute NaOH to each of the salts which were now mixed with 1cm^3 of water; Y formed a precipitate (initially the solution was colourless as the solute had dissolved) whilst X turned colourless (X's solution was initially insoluble and was therefore a ppt before)
    What conclusions could I draw from these observations? I think it might have something to do with Y having an ion that is insoluble when added to OH (ie Be and Mg) and vice versa... but im not too sure...

    Another test was adding AgNO3 + nitric acid, and in another I added BaCl2 - what could these show me?
  2. jcsd
  3. Nov 14, 2007 #2
    Very difficult question with only these data.

    1. X and Y are necessarily salts or can also be oxides/idroxydes?
    2. group 2 include also 2b, that is Zn, Cd, Hg?
    3. How dilute is NaOH? Can you specify better the concentration or the pH of the solution?

    About substance X: an insoluble group 2 salt that dissolves with diluted NaOH, have I understood correctly?

    Berillium idroxyde, carbonate, phosphate are insoluble but dissolves in high alcaline solutions ( not very diluted, then). The same with Zinc, for example.

    About Y, there are many elements and many salts for every of those elements which dissolve in water and precipitates with OH-:

    Mg (alogenides, nitrate, sulfate), Ca (alogenides, nitrate), Cd (alogenides, nitrate, sulfate), Hg (Hg(II) alogenides, nitrate).

    Be and Zn precipitates with diluted sol. of OH- and re-dissolves in high con. of OH-.
  4. Nov 17, 2007 #3
    AgNO3 will help you to find out if there are halide ions (chloride, iodide, bromide,..) in the salts X and Y.

    BaCl2 will tell you if sulphate is present.

    These two tests determine the anions.

    the test with NaOH will help to distinguish the cation.

    and i think Y is MgCl2 or MgSO4. you will know that when you test the anion. A white ppt. is formed when you add the Mg salt to NaOH.

    This appears to be a school lab experiment. simple and easily available reagents are involved.
    Last edited: Nov 17, 2007
  5. Nov 17, 2007 #4
    I don't think so. Which should be the reaction?
  6. Nov 17, 2007 #5
    o yeah, of course, X is NOT BaSO4, i will correct that right here. i think more information is required. sorry
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook