Question

Define faraday law of electrolysis how much electricity in terms of faraday is required 20 gram of calcium from

Answer 1

faraday law of electrolysis: (it is also called as faraday's 1st law)

The mass of the substance (m) deposited or liberated at any electrode is directly proportional to the quantity of electricity or charge (Q) passed.

electricity in terms of faraday is required 20 gram of calcium from:

$Ca^{2+}$ $2e^{-}$ ⇒ Ca

                                                          40g

the energy requried for 40g is 2F hence the enery requried for 20g is

        =2×20/40

        = 1 F

Answer 2

Faraday's First Law of Electrolysis. The mass of the substance (m) deposited or liberated at any electrode is directly proportional to the quantity ofelectricity or charge (Q) passed. ...Faraday further observed that 1Faraday (96,485C) of charge liberates 1 gram equivalent of the substance at the electrodes.




The balance reaction will 
The charge on Ca in CaCl2
Ca + 2Cl ���� = 0 
Cl has �1 charge so that 
Ca� + 2(�1) = 0 
Ca� ������������ = 2 
We have to get 2o g Ca from Ca2+
Number of required moles� = mass / molar mass
Molar mass of Ca is 40 g/mol and required mass of Ca is 20 g 
Hence number of moles� �������� = 20/40 ���� = 0.5 mol 
Electricity required to produce 1 mol of calcium = 2 F
The electricity required to produce 0.5 mol of calcium
= 0.5 � 2 F
�� = 1 F