What is the cause of the color change observed when $H C l$ $HCl$ is added to the complex ion ${[C u {(N H_{3})}_{4}]}_{4}^{2 +}$ $[Cu(NH_3)_4]^(2+)$ ?

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Answer 1 · 2017-07-18T03:13:51

I have explained a similar ligand displacement reaction to this in the answer below:

In this case the complex we have is tetraammine copper(II):

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If excess chloride ions are added the ammonia ligands are displaced and the green, tetrachloro copper(II) complex forms:

$sf(color(blue)([Cu(NH_3)_4(H_2O)_2]^(2+))+4Cl^(-)rarrcolor(green)([CuCl_4]^(2-))+4NH_3+2H_2O)$

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The solution looks like this:

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What is the cause of the color change observed when HClHClHCl is added to the complex ion [Cu(NH_3)_4]^(2+)[Cu(NH3)4]2+[Cu(NH_3)_4]^(2+)?