JEE Mains · Chemistry · STD 12 - 5. Co-ordination chemistry
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 \({\left[ {CoC{l_4}} \right]^{2 - }}\)
- B \({\left[ {CoC{l_6}} \right]^{3 - }}\)
- C \({\left[ {CoC{l_6}} \right]^{4 - }}\)
- D \({\left[ {Co{{\left( {{H_2}O} \right)}_6}} \right]^{2 + }}\)
Answer & Solution
Correct Answer
(A) \({\left[ {CoC{l_4}} \right]^{2 - }}\)
Step-by-step Solution
Detailed explanation
Aqueous of solution of \(CoCl_2\) contains \([Co(H_2O)_6]^{2+}\) which is pinkish in colour so option \((d)\) is incorrect. Reduction potential of \(C{o^{3 \oplus }} \to C{o^{2 \oplus }}\) is high so option \((b)\) is incorrect. \(Co^{2+}\) does not oxidises easily to…
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