Electrochemistry Ques 60
60. In the silver plating of copper, $K[Ag(CN)_2]$ is used instead of $AgNO_3$. The reason is [2002]
(a) A thin layer of $Ag$ is formed on $Cu$
(b) More voltage is required
(c) $Ag^{+}$ions are completely removed from solution
(d) Less availability of $Ag^{+}$ions, as $Cu$ cannot displace $Ag$ from $[Ag(CN)_2]$ ion
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Solution:
- (d) In the silver plating of copper, $K[Ag(CN)_2]$ is used instead of $AgNO_3$. Copper being more electropositive readily precipitate silver from their salt solution
$Cu+2 AgNO_3 \longrightarrow Cu(NO_3)_2+Ag$
whereas in $K[Ag(CN)_2]$ solution a complex anion $[Ag(CN)_2]^{-}$is formed and hence $Ag^{+}$are less available in the solution and therefore copper cannot displace $Ag$ from its complex ion.
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