NCERT Class XII Chemistry
Chapter - Electrochemistry
Questions with Solutions
© examsnet.com
Question : 13
Total: 32
How much electricity in terms of Faraday is required to produce
(i) 20.0 g of Ca from moltenC a C l 2
(ii) 40.0 g of Al from moltenA l 2 O 3
(i) 20.0 g of Ca from molten
(ii) 40.0 g of Al from molten
Solution:
(i) C a C l 2 → C a 2 + + 2 C l –
or,C a 2 + +
→
∵ 40 g of calcium needs = 2 mole of electrons
= 2 × 96500 coulombs
∴ 20 g of calcium needs = 96500 coulombs (1F).
A l 2 O 3 → 2 A l 3 + + 3 O 2 –
or,A l 3 + +
→
∵ 27 g of aluminium needs = 3 mole of electrons
= 3 × 96500 coulombs
∴ 40.0 g of aluminium needs =
= 4.28888 × 105
or,
∵ 40 g of calcium needs = 2 mole of electrons
= 2 × 96500 coulombs
∴ 20 g of calcium needs = 96500 coulombs (1F).
or,
∵ 27 g of aluminium needs = 3 mole of electrons
= 3 × 96500 coulombs
∴ 40.0 g of aluminium needs =
= 4.28888 × 10
© examsnet.com
Go to Question: