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Investigate the range of complexes formed by transition elements

  1. Sep 14, 2004 #1
    We mixed 3 ml of 1M copper solfate solution and 3ml of sodium chloride solution.

    This main copper ions are presented as Cu(h20)6 2+

    We heated the test tube to produce cucl42- ions.

    This is part a)

    We placed 1M of copper2 sulfate solution in anoter test about 2 cm depth and slowly added 1 M sodium hydroxide solution and a thick precipitate formed.

    We added 2M ammonia solution to this mixture and cy(Nh3)4 2+ ions are formed.

    This is part b)

    Is it possible to use stoichiometry to calculate the respective concentration, num of moles of them all




  2. jcsd
  3. Sep 15, 2004 #2


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    Yes, it is possible, for all reactions, that you may calculate the stoichiometry of almost all reactions, providing that you know molarity and volume of reactants.

    Aqueous copper sulfate exists as [Cu(H2O)6]SO4. You know molarity and volume, so just multiply them with each other to obtain the mole amount. You'll get 3 mmol.

    [Cu(H2O)6]SO4 + 4 NaCl ---> Na2[CuCl4] + Na2SO4 + 6 H2O

    This reaction is only possible in the presence of high chloride concentrations; water is a stronger ligand and it is not very easy to remove complexed water from the complex.

    You formed a copper hydroxide precipitate (light blue) by adding sodium hydroxide; and then added ammonia to convert this into tetraminecopper hydroxide:

    CuSO4 + 2NaOH --> Cu(OH)2 + Na2SO4

    Cu(OH)2 + 4NH3 --> [Cu(NH3)4](OH)2

    You'll need to know the final volume of the reaction medium; then you can calculate the concentrations as inorganic reactions have yields as much as about 95-100%

    Regards, chem_tr
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