Question

Procedure:

1. Obtain six 2 mL plastic cuvettes from your TA. Make sure you are wearing proper safety equipment including gloves.

2. Add 1.5 mL of 0.05M copper sulfate solution to its respective cuvette.

3. Measure the absorbance (max) using the Ocean Optics UV-vis spectrophotometer. Make sure that you use a kimwipe to remove any fingerprints from the cuvette before making a measurement. Your TA will assist you with the operation of the spectrophotometer. 3

4. As a general guideline, the copper(II)sulfate should fill approximately ¼ of the volume of the cuvette and the lihand the other ¾ volume so that the ratio of ligand to metal is 3:1.

5. In another cuvette, add 0.5 mL of 0.05 M copper sulfate solution. Carefully measure out 1.5mL of 0.05M EDTA solution and add it to the cuvette containing the copper sulfate.

6. Repeat step 3.

7. In another cuvette, add 0.05 mL of 0.05M copper sulfate solution. Carefully measure out 1.5mL of 0.05 sodium nitrite solution and add it to the cuvette.

8. Repeat step 3.

9. In another cuvette, add 0.05 mL of 0.05M copper sulfate solution. Carefully measure out 1.5mL of 0.05M ethylenediamine.

10. Repeat step 3.

11. In another cuvette, add 0.05 mL of 0.05M copper sulfate solution. IN THE HOOD!!! Carefully remove the cap from the ethylenediamine bottle and, using a new pipette each time, extract a pipette full of ethylenediamine. IMMEDIATELY REPLACE THE CAP ON THE REAGENT!!! Add the ethylenediamine in a dropwise manner to the copper sulfate solution until a dark purple color appears. Shake the solution till it becomes homogenous.

12. Repeat step 3.

13. Record all the necessary measurements before discarding your solutions in the appropriate waste container.

Max of lowest energy for Copper (II) complexes

Name of the Compound max

copper sulfate 810nm

copper sulfate/EDTA 350nm

copper sulfate/sodium nitrite 400nm

copper sulfate/ethylenediamine (16.5M) 550nm

copper sulfate II /ethylenediamine (0.05M) 950nm

1. Calculate the corresponding crystal field splitting energy values for each of the copper(II) complexes with the different ligands used above.

2. Based upon the information above, create a spectrochemical series for the copper(II) ligands.

3. Draw a crystal field energy-level diagram, assign the electrons to orbitals, and predict the number of unpaired electrons for tris(en)cuprate(II) (low spin).