Electrochemistry Question 10
Question 10 - 31 January - Shift 1
Which one of the following statements is correct for electrolysis of brine solution?
(1) $Cl_2$ is formed at cathode
(2) $O_2$ is formed at cathode
(3) $H_2$ is formed at anode
(4) $OH^{-}$is formed at cathode
Show Answer
Answer: (4)
Solution:
Electrolysis of brine solution
$NaCl$ (aq.) $\longrightarrow Na _{\text{(aq) }}^{+}+Cl _{\text{(aq) }}^{+}$
At anode : $2 Cl _{\text{(aq.) }}^{+} \longrightarrow Cl_2(g)+2 e^{-}$
(Major)
$2 H_2 O _{(\ell)} \longrightarrow \underset{\text{ Minor }}{O _{2(g)}^{m}}+4 H _{(aq)}^{+}+4 e$
At Cathode : $2 H_2 O _{(\ell)}+2 e^{-} \longrightarrow H _{2(g)} \uparrow+2 OH _{(aq)}^{-}$
$2 Na^{+}+2 OH^{-} \longrightarrow 2 NaOH$
