It is the process of decomposition of an electrolyte by the passage of electricity through its aqueous solution or molten state.
Faraday’s first law of electrolysis:
In a chemical reaction, the amount of any substance deposited or liberated is directly proportional to the quantity of electricity passed through it.
Faraday’s second law of electrolysis:
When the same quantity of electricity is passed through the different electrolytes connected in series. The weights of the substance produced at the electrodes are directly proportional to their equivalent weights.
Conductance of electrolytic solution:-
Electrolytes conducts electricity by decomposition.
If voltage v is applied to the ends of the conductor and current “I” floe through it, then the resistance “R”of the conductor is V/I (ohm).
The reciprocal of electrical resistance is called conductance. And is represented by G sign
Specific conductance or conductivity:-
The reciprocal of resistivity is known as conductivity. And is denoted by k (kappa).
Equivalent conductivity of a solution at a dilution v is defined as the conductance of all the ions produced from one gram equivalent of the electrolyte dissolved in v cm3 of the solution when the distance between the electrode is one cm and the area of the electrode is so large then whole the solution is come between them.
Where, c is molar concentration.
Kohlrausch law: –
The limiting molar conductivity of an electrolyte (i.e. molar conductivity at infinite dilution) is the sum of the limiting ionic conductivities of the cation and the anion each multiplied with the number of ions present in one formula unit of the electrolyte.
Kohlrausch law in terms of equivalent conductivity:-
The equivalent conductivity of an electrolyte at infinite dilution is the sum of two values one depends upon cation and other upon anion.
Electrode Potential :-
The electrical potential difference set up between metals and its ions in the solution is called electrode potential.
The various electrodes have been arranged in order of their increasing value of standard reduction potentials. This arrangement is called electrochemical series.
Nernst equation for electrode potential:-
It consist of a cylindrical zinc container which acts as a anode. A graphite rod is placed between the center, acts as a cathode. The space between the cathode and the anode is so packed with the paste of NH4Cl and ZnCl2 and graphite is surrounded by MnO2 and carbon.
Mercury cell (Ruber Mallory cell) :-
It consists of zinc container as anode, a carbon rod as cathode and a paste of mercuric oxide mixed with KOH as the electrolyte a lining of porous paper separate the electrolyte from zinc container.
Lead storage battery:-
cell consist of lead anode and a grid of lead packed with lead dioxide acts as lead cathode. These electrodes are arranged alternatively separated by fiber glass sheet and suspended in sulfuric acid (dilute) which acts as electrolyte.
Electrode reaction occurs during discharge battery:-
The electrode reaction is reserved.
Nickel Cadmium Storage Cell:-
It consists of cadmium electrode (as Anode) and metal grid of nickel (iv) oxide as cathode immersed in KOH solution.
Reaction occurs during discharge of cell:-
Fuel cell: –
It consists of porous carbon electrodes containing suitable catalyst incorporated in them. Concentrated KOH or NaOH solution is placed between the electrodes to act as the electrolyte. The hydrogen or oxygen gases are bubbled through the porous electrode into the KOH/NaOH solution.
The process of slowly eating away of metal due to attack of atmospheric gases on the surface of metal resulting into the formation of compounds such as oxides, sulphides, carbonates, sulphates etc. is called as corrosion.