When concentrated HCl is added to an aqueous solution of CoCl2, its colour changes from reddish pink to deep blue. Which complex ion gives blue colour in this reaction ?

Question

When concentrated HCl is added to an aqueous solution of CoCl2, its colour changes from reddish pink to deep blue. Which complex ion gives blue colour in this reaction ? (A) [ CoCl 6]4- (B) [ CoCl 6]3- (C) [ CoCl 4]2- (D) [ Co ( H 2 O )6]2+

Tardigrade Admin · Accepted Answer

[ COCl 4]-2 blue [ CO ( H 2 O )6]+2 pink ]

Q. When concentrated $H Cl$ is added to an aqueous solution of $C o C l_{2}$ , its colour changes from reddish pink to deep blue. Which complex ion gives blue colour in this reaction ?

$[C o C l_{6}]^{4 -}$

$[C o C l_{6}]^{3 -}$

$[C o C l_{4}]^{2 -}$

$[C o (H_{2} O)_{6}]^{2 +}$

$[COC l_{4}]^{- 2}$ blue

$[CO (H_{2} O)_{6}]^{+ 2}$ pink $]$

Q. When concentrated HCl is added to an aqueous solution of CoCl2​, its colour changes from reddish pink to deep blue. Which complex ion gives blue colour in this reaction ?

[CoCl6​]4−

[CoCl6​]3−

[CoCl4​]2−

[Co(H2​O)6​]2+