This is an in-class activity that I made to help students in my second semester general chemistry course work through some aspects of color and coordination chemistry. The activity was performed with a demonstration of color for nickel coordination complexes (ligands: water, ethylenediamine, and ammonia). I also included equilibria and thermodynamics as those concepts apply to coordination compounds at the introductory level. This served as a review of the concepts as well.
1. Students will demonstrate the relationship between observed colors to absorbed colors in visible spectroscopy.
2. Students will qualitatively rank crystal field splitting strengths to the absorbed color and therefore rank ligands according to their field strength.
3. Students will use prior experience with concepts of chemical equilibria and chemical thermodynamics to make assertions about stability and driving forces for reaction of several coordination compounds.
4. If the related demonstration is performed at the time of the activity, students will use observations to explain chemical phenomena regarding several related coordination compounds.
None beyond the worksheet unless one of the associated demonstrations (links below) are performed. If desired, a visible spectrometer could be used to measure the wavelengths of maximum absorbance for a more quantitative approach to ranking the ligands.
I performed this activity in my second semester general chemistry lecture (38 students). I made the complexes (excepting the EDTA complex, although I could have made it) for them in class and allowed them to inspect the colors. Students worked in small groups (2-4students) to complete the worksheet.