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Electrolysis and Electrolytes

In the electr...

Question

In the electrolysis of aqueous sodium chloride solution, which of the half cell reaction will occur at anode $?$

H_{(a q)}^{+} + e^{-} \to \frac{1}{2} H_{2}; E_{c e l l}^{o} = 0.00

volts

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N a_{(a q)}^{+} + e^{-} \to N a_{(s)}; E_{c e l l}^{o} = 2.71

volts

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C l_{(a q)}^{-} + e^{-} \to \frac{1}{2} C l_{2}

;

E_{c e l l}^{0} = 1.36

volts

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2 H_{2} O^{(l)} \to O_{2} + 4 H^{+} + 4 e^{-}; E_{c e l l}^{o} = 1.23

volts$

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Solution

The correct option is C $C l_{(a q)}^{-} + e^{-} \to \frac{1}{2} C l_{2}$ ; $E_{c e l l}^{0} = 1.36$ volts
In the electrolysis of aqueous sodium chloride solution, chlorine gas is liberated at the anode.

$C l_{(a q)}^{-} + e^{-} \to \frac{1}{2} C l_{2}$

$E_{c e l l}^{0} = 1.36 V$ .

This is because $C l^{-}$ ions have lower discharge potential than $O H^{-}$ ions.

Hence, the correct option is $C$ .

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Similar questions

N a^{+} (a q) + e^{-} \to N a (s) E^{0} = - 2.71 V

H^{+} (a q) + e^{-} \to \frac{1}{2} H_{2} (g) E^{0} = 0.00 V

(E^{0})

N a^{+} (a q) + e^{-} \to N a (s) E^{0} = - 2.71 V

H^{+} (a q) + e^{-} \to \frac{1}{2} H_{2} (g) E^{0} = 0.00 V

(E^{0})

(a) Following reactions occur at cathode during the electrolysis of aqueous sodium chloride solution:

$N a^{+} (a q) + e^{-} \to N a (s) E^{\circ} = - 2.71 V$
$H^{+} (a q) + e^{-} \to \frac{1}{2} H_{2} (g) E^{\circ} = 0.00 V$

On the basis of their standard reduction electrode potential $(E^{\circ})$ values, which reaction is feasible at the cathode and why?

(b) Why does the cell potential of mercury cell remain constant throughout its life?

E_{C e l l}^{o}

Z n (s) + C u^{2 +} (a q) \to Z n^{2 +} (a q) + C u (s)

E_{C u^{2 +} / C u}^{\circ} = 0.34 V, E_{Z n^{2 +} / Z n}^{\circ} = - 0.76 V

O_{2} (g)

⎡ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ \begin{matrix} (c o r r e c t) C u (s) ⟶ & C u^{2 +} (a q) + 2 e^{-} E_{C u | C u^{2 +}}^{⊝} = - 0.34 V (w r o n g) 2 H_{2} O (l) ⟶ & O_{2} (g) + 4 H^{\oplus} (a q) + 4 e^{-} E_{H_{2} O | O_{2}}^{⊝} = - 1.23 V \end{matrix} ⎤ ⎥ ⎥ ⎥ ⎥ ⎥ ⎦

\begin{matrix} I n (d) \end{matrix}

⎡ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎢ ⎣ \begin{matrix} (c o r r e c t) N i (s) ⟶ & N i^{2 +} (a q) + 2 e^{-} E_{N i | N i^{2 +}}^{⊝} = - 0.25 V (w r o n g) 4 ⊝ O H (a q) ⟶ & O_{2} (g) + 2 H_{2} O (l) + 4 e^{-} E_{⊝ O H | O_{2}}^{\oplus} = - 0.4 V \end{matrix} ⎤ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎥ ⎦

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