Problem 38 - Chemistry: An Atoms-Focused Approach

Question

Which of the following complex ions should absorb the shortest wavelengths of electromagnetic radiation? (a) \(\mathrm{CuCl}_{4}^{2-} ;\) (b) \(\mathrm{CuF}_{4}^{2-} ;\) (c) \(\mathrm{CuI}_{4}^{2-} ;\) (d) \(\mathrm{CuBr}_{4}^{2-}\)

Step-by-Step Solution

Answer

Answer: The complex ion that absorbs the shortest wavelengths of electromagnetic radiation is (b) \(\mathrm{CuF}_{4}^{2-}\).

Step 1: Identify the Ligands in Each Complex Ion

We need to identify the ligands present in each given complex ion: (a) \(\mathrm{CuCl}_{4}^{2-}\) - the ligand is \(\mathrm{Cl}^-\) (b) \(\mathrm{CuF}_{4}^{2-}\) - the ligand is \(\mathrm{F}^-\) (c) \(\mathrm{CuI}_{4}^{2-}\) - the ligand is \(\mathrm{I}^-\) (d) \(\mathrm{CuBr}_{4}^{2-}\) - the ligand is \(\mathrm{Br}^-\)

Step 2: Rank the Ligands Based on Spectrochemical Series

Based on the spectrochemical series (I- < Br- < Cl- < F-), the ranking of the ligands is as follows: 1. \(\mathrm{F}^-\) - strongest 2. \(\mathrm{Cl}^-\) 3. \(\mathrm{Br}^-\) 4. \(\mathrm{I}^-\) - weakest

Step 3: Determine the Complex Ion Absorbing the Shortest Wavelengths

Since the strongest ligands create larger energy differences, the complex ion with the strongest ligand will absorb the shortest wavelengths of electromagnetic radiation. In this case, the complex ion \(\mathrm{CuF}_{4}^{2-}\) has the strongest ligand (F-).

Step 4: Conclusion

Therefore, the complex ion that should absorb the shortest wavelengths of electromagnetic radiation is \(\mathrm{CuF}_{4}^{2-}\).