6.28 Name the processes from which chlorine is obtained as a by-product. What will happen if an aqueous solution of NaCl is subjected to electrolysis?

In the electrolysis of NaCl by Down's process, chlorine is obtained as a by-product. This process involves the electrolysis of a fused mixture of NaCl and CaCl₂ at 873K. during electrolysis, sodium is liberated at the cathode and Cl₂ is liberated at the anode.

If an aqueous solution of NaCl is electrolysed, H₂ is evolved at the cathode and Cl₂ is obtained at the anode, the reason being that E⁰ of Na⁺/Na redox couple is much lower (E⁰ = - 2.71 V) than that of H₂O (E_H2O/H2⁰    = - 0.83V ) and hence water is reduced to H in presence of Na⁺ ions. However, NaOH is obtained in the solution.

<p>In the electrolysis of NaCl by Down's process, chlorine is obtained as a by-product. This process involves the electrolysis of a fused mixture of NaCl and CaCl₂ at 873K. during electrolysis, sodium is liberated at the cathode and Cl₂ is liberated at the anode.</p><div><div><picture><source srcset="https://images.shiksha.com/mediadata/images/articles/1687932520php3BFc85_480x360.jpeg" media=" (max-width: 500px)"><img src="https://images.shiksha.com/mediadata/images/articles/1687932520php3BFc85.jpeg" alt="" width="306" height="116"></picture></div></div><p>If an aqueous solution of NaCl is electrolysed, H₂ is evolved at the cathode and Cl₂ is obtained at the anode, the reason being that E⁰ of Na⁺/Na redox couple is much lower (E⁰ = - 2.71 V) than that of H₂O (E_H2O/H2⁰&nbsp;&nbsp;&nbsp; = - 0.83V ) and hence water is reduced to H in presence of Na⁺ ions. However, NaOH is obtained in the solution.</p><div><div><picture><source srcset="https://images.shiksha.com/mediadata/images/articles/1687932537phpg93q82_480x360.jpeg" media=" (max-width: 500px)"><img src="https://images.shiksha.com/mediadata/images/articles/1687932537phpg93q82.jpeg" alt="" width="323" height="92"></picture></div></div>

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