Chapter 20, Problem 20.119SP

Interpretation Introduction

Interpretation:

The colour of Cr+3 (aq) cation should be explained in comparison to the colourless Y+3 (aq.) cation.

Concept introduction:

As per crystal field theory, the colour in complex compound can be because of various reasons in which d-d transition of electrons are most common.
The different colours of similar metal ion complexes can be because of the difference in the ligands attached and the range of their absorptions.
To explain the colour of any complex or ion, the colour wheel is used. If a compound absorbs a particular colour of any range on the colour wheel then the colour just opposite to the wheel will be the colour shown or reflected by the compound.
Also, if the colour of compound is given then the absorption range can be obtained by using opposite colour of the colour wheel.

The wheel can be shown as: