Single Choice

Correct increasing order for the wavelengths of absorption in the visible region for the complexes of $$Co^{3+}$$ is:

A$$[Co(NH_{3})_{6}]^{3+}<[Co(en)_{3}]^{3+}<[Co(H_{2}O)_{6}]^{3+}$$
B$$[Co(en)_{3}]^{3+}<[Co(NH_{3})_{6}]^{3+},<[Co(H_{2}O)_{6}]^{3+}$$
Correct Answer
C$$[Co(H_{2}O)_{6}]^{3+}<[Co(en)_{3}]^{3+}<[Co(NH_{3})_{6}]^{3+}$$
D$$[Co(H_{2}O)_{6}]^{3+}<[Co(NH_{3})_{6}]^{3+}<[Co(en)_{3}]^{3+}$$

Solution

The increasing order for the wavelengths of absorption in the visible region for the complexes of $$Co^{3+}$$ is $$\displaystyle [Co(en)_{3}]^{3+} < [Co(NH_{3})_{6}]^{3+} < [Co(H_{2}O)_{6}]^{3+}$$.
The decreasing order of ligands strength is $$\displaystyle en > NH_3 > H_2O$$. Stronger ligand causes greater splitting between two energy levels.
The energy of light absorbed is more and the wavelength of light absorbed is less for the stronger ligand.

SIMILAR QUESTIONS

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