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 .