Question

help with questions 2,4 and 5 please!!! Lab is Complex Ion Composition by Job's Method and ligand is ethylenediamine.

2. Procedure Using solutions of NiSO4 6H 0 (0.4M) and ethylenediamine (0.4M) prepare solutions having a total volume of 10.0ml in which the mole fraction of ethylenediamine, X, is 0.0, 0.3, 0.4, 0.5, 0.6, 0.8 and 0.9. Determine the absorbance of each solution at the following wavelengths: 530, 545, 578,622 and 640 nm. By appropriate graphical methods, obtain a possible formula to represent the predominant species present in nickel (11)-1, 2-diaminoethane solutions. Post-lab Questions 1. Write structural formulas for the three possible products of reaction of ethylenediamine with Ni(H2O).*? 2. What does the absorption spectrum of the ligand, ethylenediamine, look like in the visible region which you used in this experiment. Assign the absorption maxima you used in this experiment to individual species in the system, where this is possible. 3. What would happen if the values of K, and K, were larger than K, 7 Could you still use Job's method? 4. From the observed changes in the spectra and a knowledge of the complexes present in the solutions, what can be said about the relative ligand field strengths of en and H,O? 5. In what region of the visible range would you expect the results to be most accurate, why?

Answer 1

The structural formulas of the three possible products can be written as follows.

(i) [Ni(H₂O)₄(en)]²⁺

(i) [Ni(H₂O)₂(en)₂]²⁺

(i) [Ni(en)₃]²⁺