Chapter 21, Problem 61E

Interpretation Introduction

Interpretation: Three test tubes containing different complex ions are given. The color of light absorbed by each given ion is to be predicted. The identity of complex ion in each test tube is to be predicted.

Concept introduction: The capacity to absorb light by complex ion is directly proportional to crystal field splitting energy and energy absorbed is inversely proportional to the wavelength.

To determine: The color of light absorbed by each ion $\text{Cr}{\left({\text{H}}_2\text{O}\right)}_{\text{6}}{}^{3+},\text{Cr}{\left({\text{NH}}_3\right)}_{\text{6}}{}^{3-},\text{Cr}{\left({\text{H}}_2\text{O}\right)}_{\text{4}}{\text{Cl}}_{\text{2}}{}^{+}$ and the identity of complex ion in each test tube.

The order of increasing crystal field splitting energy for complex ions $\text{Cr}{\left({\text{H}}_2\text{O}\right)}_{\text{6}}{}^{3+},\text{Cr}{\left({\text{NH}}_3\right)}_{\text{6}}{}^{3-},\text{Cr}{\left({\text{H}}_2\text{O}\right)}_{\text{4}}{\text{Cl}}_{\text{2}}{}^{+}$ is,

$\text{Cr}{\left({\text{NH}}_3\right)}_{\text{6}}{}^{3-}>\text{Cr}{\left({\text{H}}_2\text{O}\right)}_{\text{6}}{}^{3+}>\text{Cr}{\left({\text{H}}_2\text{O}\right)}_{\text{4}}{\text{Cl}}_{\text{2}}{}^{+}$