Friday, April 30, 2010

Faraday's First Law of Electrolysis:

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Faraday's put forward his two laws of electrolysis in 1833.

Statement:

The mass of an elements which is deposited on an electrode during electrolysis is directly proportional to the quantity of electricity which passes through the electrolyte.

Explanation:

If W is the amount of substance which liberates or deposited at the electrode on passing the electricity through the electrolyte and the quantity of electricity is Q, then

$W\,\alpha \,Q$

or W = ZQ

Z is the electrochemical constant for a given substance.

As $Q\,=\,A\times \,t$

$\therefore$ We can write the statement of the first law of electrolysis mathematically as under:

$W\times A\times t$

or W= Zat

If 1 ampere electric current passes through the electrolyte for 1 second then W=Z It means that on passing the current of 1 ampere for 1 second the weight of the substance deposited is equal to the electrochemical constant. For doing the calculations of electrochemical problems, we must know the units too.

unit of charge (Q) = Coulomb (C)
unit of mass (m) = Kilogram (kg)
unit of current (A) = ampere (A)
unit of electrochemical equivalent (Z) = kg/C

Note:
Faraday's first law of electrolysis is written as:

W = ZAt

Here;

W= is actually mass and not weight, as mas is commonly called weight.
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