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

Tardigrade Admin · Accepted Answer

When concentrated HCl is added in an aqueous solution of CoCl 2 then it forms [ CoCl 4]2- complex. underset textPink colour complex[ Co ( H 2 O )6]2++4 Cl - longrightarrow underset textBlue colour complex[ Co ( Cl 4)]2-+6 H 2 O

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?

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

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

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

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

When concentrated $H Cl$ is added in an aqueous solution of $C o C l_{2}$ then it forms $[C o C l_{4}]^{2 -}$ complex.
$Pink colour complex [C o (H_{2} O)_{6}]^{2 +} + 4 C l^{-} ⟶ Blue colour complex [C o (C l_{4})]^{2 -} + 6 H_{2} O$

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?

[CoCl4​]2−

[CoCl6​]3−

[CoCl6​]4−

[Co(H2​O)6​]2+