Question
State your observation for the following electrolytic reaction
Aqueous copper sulphate is electrolysed between platinum electrodes.
Aqueous copper sulphate is electrolysed between platinum electrodes.
✓
Answer
When the electrolysis of copper sulphate(aqueous) is electrolysed between platinum electrodes the following reaction follows :
$\begin{aligned} & CuSO _4 \rightleftharpoons Cu ^{+2}+ SO _4^{2-} \\ & H _2 O \rightleftharpoons H ^{+}+ OH ^{-}\end{aligned}$
Reaction at cathode : Copper ions and hydrogen ions migrate towards the cathode, $Cu ^{+2}$ ions being lower in the electrochemical series are preferentially discharged to hydrogen ions to form neutral copper atoms at platinum cathode.
$
Cu ^{+2}+2^{e-} \longrightarrow Cu
$
Reaction at anode: Sulphate ions and hydroxyl ions migrate towards the anode, Hydroxyl ions are preferentially discharged to sulphate ions at anode, to form neutral particles of $OH ^{-}$, The electrically neutral hydroxyl reacts
among themselves to give water and oxygen.
$
\begin{aligned}
& OH ^{-}- e ^{-} \longrightarrow OH \\
& 4( OH ) \xrightarrow{-4 e ^{-}} 2 H _2 O + O _2
\end{aligned}
$
$\begin{aligned} & CuSO _4 \rightleftharpoons Cu ^{+2}+ SO _4^{2-} \\ & H _2 O \rightleftharpoons H ^{+}+ OH ^{-}\end{aligned}$
Reaction at cathode : Copper ions and hydrogen ions migrate towards the cathode, $Cu ^{+2}$ ions being lower in the electrochemical series are preferentially discharged to hydrogen ions to form neutral copper atoms at platinum cathode.
$
Cu ^{+2}+2^{e-} \longrightarrow Cu
$
Reaction at anode: Sulphate ions and hydroxyl ions migrate towards the anode, Hydroxyl ions are preferentially discharged to sulphate ions at anode, to form neutral particles of $OH ^{-}$, The electrically neutral hydroxyl reacts
among themselves to give water and oxygen.
$
\begin{aligned}
& OH ^{-}- e ^{-} \longrightarrow OH \\
& 4( OH ) \xrightarrow{-4 e ^{-}} 2 H _2 O + O _2
\end{aligned}
$
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