Electrochemistry

Electrochemistry
: It is branch of chemistry which deals with relationship b/w clectrical energy & chemical changes taking place in redox reactions.

Electrolysis
: Process of decomposition of an electrolyte by passage of electricity through its aq. solution or molten state.
Mechanism of electrolysis
: Electro dissociates producing +ve & -vely charged ions. On passing electric current, positively charged ions move towards cathode & hence c/d cations & lose their respective charge. Similarly -ve ions moves towards Anode c/d anions. So, oxidation occursat anode while reduction takes place at cathode.
Electrolysis water
: Initialy, ammeter does not show any deflection. b/c water is bad conductor of elecricity.

WHen few drops od oil. H2SO4
are added to water, ammeter shows a deflection & electrolysis begins. As a result electrolysis, oxygen isproduced at anode & H
2at cathode.Vol. of H2
evolved is double that of oxygen.
H2O(l)H+(aq.) + on-(aq.)    H2SO4(aq.)2H+(as) + SO42-(aq.)
When electric current is passed through it, H+
ions moves towards cathode & on
-& SO42-
ions move towards anode.
Since discharge potential of on
-ions is much lower than that of SO42-ions. So, SO42-
ions remains in sol.
At Cathode
:
H+(aq) + e- H.    (primary change)    H. + H.H2(I)    (Secondary Change)

At Anode
:    on-(aq.) - e- OH    4OH2H2O + O2
Overall reaction
:    4H+(aq.) + 4on-(aq.)
2H2(aq) + 2H2O(l) + O2(I)
Faraday's Ist law of electrolysis
: Mass of any substance deposited or liberated at any electrode is directly proportional to quantity of electricity passed.
If Wg of substance deposited on passing Q coulombs of electricity. then,
W
W = z     z
electrochemical equivalent
If current of camperes is passed for t seconds, then
Q = c x t
    W = z = zct
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Faraday's IInd law
: When same quantity of electricity is passed through solutions of different electrolytes connected in series, weights of substances...