Investigate the range of complexes formed by transition elements

[dagg3r]

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.

 

[chem_tr]

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