Of the following complex ions: [CoCl(NH₃)₅]^2+,[Co(NH₃)₆]³⁺,[Co(en)₃]³⁺,[Co(H₂O)₆]³⁺,one appears pink,two are yellow,and one blue.Which is blue? A)[Co(NH₃)₆]³⁺ B)[CoCl(NH₃)₅]²⁺ C)[Co(H₂O)₆]³⁺ D)[Co(en)₃]³⁺ E)both [Co(en)₃]³⁺ and [Co(H₂O)₆]³⁺

Question

Quizplus · Accepted Answer

Coordination compounds appear colored due to d-d transitions of electrons between different energy levels in the metal ion. The color of a complex depends on the metal, the ligands, and the geometry of the complex. In this case, the blue complex is [Co(H₂O)₆]³⁺, which likely has a larger crystal field splitting due to the stronger-field ligand H₂O. The other complexes have pink or yellow colors due to different ligands and/or geometries.

Of the Following Complex Ions: [CoCl(NH3)5]2+, [Co(NH3)6]3+,[Co(en)3]3+,[Co(H2O)6]3+,one Appears Pink,two Are

Of the Following Complex Ions: [CoCl(NH₃)₅]^2+,[Co(NH₃)₆]³⁺,[Co(en)₃]³⁺,[Co(H₂O)₆]³⁺,one Appears Pink,two Are