Chemistry - Carbonyl compounds Question with Solution | TestHub

When aqueous solution of NaOH is added to aqueous solution of Cr (III) ion it produces [Cr(H₂O)₃(OH)₃]

$\begin{array}{ccccccc}{\left[\text{Cr}{\left({\text{H}}_2\text{O}\right)}_6\right]}^{3+}& +& \text{NaOH}& \to & \left[\text{Cr}{\left(\text{OH}\right)}_3{\left({\text{H}}_2\text{O}\right)}_3\right]& +& {\text{H}}_2\text{O}\\ & & & & \text{Light green ppt.}& & \end{array}$

Which further redissolves in aq. NaOH (in excess) to produce dark green solution due to formation of${\left[\text{Cr}{\left(\text{OH}\right)}_4\right]}^{-}$

$\begin{array}{ccccc}\left[\text{Cr}{\left(\text{OH}\right)}_3{\left({\text{H}}_2\text{O}\right)}_3\right]& +& {\text{OH}}^{\ominus }& \to & {\left[\text{Cr}{\left(\text{OH}\right)}_4\right]}^{-}\\ & & \text{Excess}& & \text{Dark green solution}\end{array}$