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23 Transition Metals and Solutions to Exercises Coordination Chemistry 23.52 (a) 6.626 10⁻³⁴ J 2.998 10⁸ m/s = 3.973 10⁻¹⁹ = 3.97 10⁻¹⁹ J/ photon 500 10⁻⁹ m photon = 3.973 J/photon 6.022 photons = = kJ/mol 1 mol (b) The spectrochemical series is an ordering of ligands according to their ability to increase the energy gap, Д. If is replaced by in the complex, the magnitude of would increase because is higher in the spectrochemical series and stronger ligand field. 23.53 Analyze/Plan. Consider the relationship between the color of a complex, the wavelength of absorbed light, and the position of a ligand in the spectrochemical series. Solve. A yellow color corresponds to absorption of a photon in the violet region of the visible spectrum, between 430 and 400 nm. The blue or green colors of aqua complexes correspond to absorptions in the region of 620 nm. The shorter wavelength corresponds to a higher-energy electron transition and larger value. Cyanide is a stronger-field ligand, and its complexes are expected to have larger values than aqua complexes. These are very general comparisons; other factors are involved, including whether the complex is high spin or low spin. 23.54 (a) [Ni(H₂O)₆ absorbs 725 nm red light and appears as the complementary color, green. absorbs 570 nm yellow light and appears as the complementary color, violet. (b) The shorter the wavelength of light absorbed, the greater the value of 4, and the stronger the ligand field. The order of increasing ligand field strength is the order of decreasing wavelength absorbed.