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Q. The equilibrium $Cu^{0}+Cu^{II}\rightleftharpoons2Cu^{I}$
In aqueous medium at $25^\circ C$ shifts towards the left in the presence of
$1.Cl^{-}2.CN^{-}3.SCN^{-}4.NO_{3}^{-}$

NTA AbhyasNTA Abhyas 2022

Solution:

$Cu ^{2+}$ ions will react with $CN ^{-}$and $SCN ^{-}$ forming $[ Cu ( CN)_4]^{3-}$ and $[ Cu ( SCN)_4]^{3-}$ leading the reaction in the backward direction.
$Cu ^{2+}+2 CN ^{-} \rightarrow Cu ( CN )_{2}$
$2 Cu ( CN )_{2} \rightarrow 2 CuCN +( CN )_{2}$
$CuCN +3 CN ^{-} \rightarrow\left[ Cu ( CN ]^{3-}\right.$
$Cu ^{2+}+4 SCN ^{-} \rightarrow\left[ Cu ( SCN ]^{3-}\right.$
$Cu ^{2+}$ also combines with $CuCl _{2}$ which reacts with $Cu$ to produce $CuCl$ pushing the reaction in the backward direction.
$CuCl _{2}+ Cu \rightarrow 2 CuCl \downarrow$