NCERT Class XII Chemistry
Chapter - Electrochemistry
Questions with Solutions
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Question : 18
Total: 32
Predict the product of electrolysis in each of the following:
(i) An aqueous solution ofA g N O 3
(ii) an aqueous solution ofA g N O 3
(iii) A dilute solution ofH 2 S O 4
(iv) An aqueous solution ofC u C l 2
(i) An aqueous solution of
(ii) an aqueous solution of
(iii) A dilute solution of
(iv) An aqueous solution of
Solution:
(i) Electrolysis of aqueous solution of A g N O 3
A g N O 3 ( s ) + a q – – – – – ▶ A g + ( a q ) + N O – 3 ( a q )
H 2 O ⇌ H + + O H −
At cathode: Ag+ + + +
At anode: As Ag anode is attacked by NO– 3 +
A g – – – – – ▶ A g + + e –
(ii) Electrolysis of aqueous solution ofA g N O 3
At cathode: Ag will be deposited.
At anode: As anode is not attacked, out of OH– – 3 – – – 3 – 2
O H – ( a q ) – – – – – ▶ O H + e –
4 O H – – – – – ▶ 2 H 2 O ( l ) + O 2 ( g )
(iii) Electrolysis of diluteH 2 S O 4
H 2 S O 4 ( a q ) 2 H + ( a q ) + S O 2 – 4 ( a q )
H 2 O ⇌ H + + O H –
At cathode:H + + e – – – – – – ▶ H ,
H + H – – – – – ▶ H 2 ( g )
At anode:O H – – – – – – ▶ O H + e – ,
4 O H – – – – – ▶ 2 H 2 O + O 2 ( g )
Thus,H 2 O 2
(iv) Electrolysis of aqueous solution ofC u C l 2
C u C l 2 ( s ) + a q – – – – – ▶ C u 2 + ( a q ) + 2 C l – ( a q )
H 2 O ⇌ H + + O H –
At cathode:C u 2 + H +
C u 2 + + 2 e – – – – – – ▶ C u
At anode: Cl– –
C l – – – – – – ▶ C l + e – ,
C l + C l – – – – – ▶ C l 2 ( g )
Thus, Cu will be deposited on the cathode andC l 2
At cathode: Ag
At anode: As Ag anode is attacked by NO
(ii) Electrolysis of aqueous solution of
At cathode: Ag will be deposited.
At anode: As anode is not attacked, out of OH
(iii) Electrolysis of dilute
At cathode:
At anode:
Thus,
(iv) Electrolysis of aqueous solution of
At cathode:
At anode: Cl
Thus, Cu will be deposited on the cathode and
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