Electrochemistry:
It is the branch of science that involves electrical energy generated by energy released by spontaneous chemical reactions and electrical energy generated by using electrical energy. chemical transformations.
Electrolytic and Metallic Conduction-
Substances which allow the passage of electric current through them are called electrical conductors or simply conductors, e.g. metals, where as those substances which do not allow such passage through them are called insulators e.g. rubber, wood etc. Conductors are of two types depending upon their physical state metallic conductors and electrolytic conductors.
Metallic Conduction
The flow of current through a metallic conductor is known as metallic conduction which occurs due to movement of free electrons or holes (positive charges). Metallic conductance is also known as electronic conduction. It depends on the type and structure of the metal, the number of valence electrons per atom, the density and temperature of the metal of inverse relation.
Electrolytic Conduction
The flow of current through an electrolytic solution gives rise to electrolytic conduction which occurs only if ions of the electrolyte are free to move.
At anode : 2Cl- → Cl₂ +2e-
At cathode : 2Na+ + 2e- → 2Na
Since, charge is carried by ions and there is exchange of electrons at the cathode and anode hence, current flows when ions are free which can be possible. If electrolyte is in molten (fused) state or in aqueous solution.
Electronic conduction depends upon the :-
(i) nature of electrolyte (whether it is weak or strong)
(ii) the inter-ionic attraction (which depends on solute-solute interactions)
(iii) the salvation of ions (which depends on solute-solvent interactions)
(iv) the viscosity of the solvent (which depends on solvent - solvent interactions)
(v) concentration of the electrolytes (inverse relation)
(vi) temperature (direct relation)
Acids, bases and their salts are the examples of electrolytes. Electrolytes may be weak or strong depending upon their dissociation. Weak electrolytes dissociate partially while strong electrolytes dissociate completely or almost completely into their ions.
Distinction between metallic conduction
and electrolytic conduction :-
Metallic Conduction
1. Electric current flows by movement of electrons.
2. No chemical change occurs.
3. It does not involve the transfer of any matter.
4. Resistance increases with increase of temperature.
5. Faraday's law is not followed.
Electrolytic Conduction
1. Electric current flows by movement of ions.
2. lons are oxidised or reduced at the electrodes.
3. Resistance decreases with increase of temperature.
4. It involves transfer of matter in the form of ions.
5. Faraday's law is followed.