NCERT Class XII Chemistry
Chapter - General Principle of Process of Isolation of Elements
Questions with Solutions
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Question : 24
Total: 31
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?
Solution:
Sodium metal is prepared by Down’s process. This process involvesthe electrolysis of a fused mixture of NaCl and C a C l 2 C l 2 N a C l ( l )
N a + ( melt ) + C l − ( melt ) N a + ( melt ) + e − – – – – ▶ N a ( s )
Anode :C l − ( melt ) – – – – ▶ C l ( g ) + e −
2 C l ( g ) – – – – ▶ C l 2 ( g )
If an aqueous solution of NaCl is electrolysed,H 2 C l 2 + H 2 O ( E 0 H 2 O ∕ H 2 ) = − 0.83 V ) H 2 + N a C l ( a q )
N a + ( a q ) + C l − ( a q ) C l − ( a q ) – – – – ▶ C l ( g ) + e −
2 C l ( g ) – – – – ▶ C l 2 ( g )
Cathode: 2 H 2 O ( l ) + 2 e − – – – – ▶ H 2 ( g ) + 2 O H − ( a q )
Anode :
If an aqueous solution of NaCl is electrolysed,
Cathode
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