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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

    Ie


    Initaially

    Reaction

    Equilibrium.
     
  2. jcsd
  3. Sep 15, 2004 #2

    chem_tr

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    Gold Member

    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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