o
The free ions Na + and Cl- present in the solution are responsible for the conductance in a solution.
o The inverse of resistivity is termed as conductivity. o
Ω = 1 / k o It is represented by the symbol( Greek, kappa). o It is measured in a unit called Sm – 1. o When length = 1m. Cross sectional area = 1m 2
Then conductivity becomes the conductance. The conductivity of an electrolytic solution depends on:
1. Nature of the electrolyte added 2. Size of the ions produced and their solvation 3. Nature of the solvent and its viscosity 4. Concentration of the electrolyte 5. It increases with the increase of temperature. 6. Pressure
o
Matters can be classified into conductors, insulators and semiconductors depending on the magnitude of their conductivity.
Conductors: o
o
Solids with conductivities ranging between 10 4 to 10 7 ohm – 1 m – 1 are conductors.
Metals have conductivities in the order of 10 7 ohm – 1 m – 1 is good conductors.
o For example, Iron, Copper, Aluminum.
Fig. Metal is used at the tip of the plug that is inserted into the socket
Insulators:
o Solids with very low conductivities ranging between 10 – 20 to 10 – 10 ohm –
1 m – 1. o For example, Wood, plastic, cloth, glass.