Define conductivity and molar conductivity for the solution of an electrolyte. Discuss their variation with concentration.

Explanation

The reciprocal of resistivity is known as specific conductance or simply conductivity. It is denoted by K (Kappa).
`K = (1)/(P) or K = Gxx(1)/(a)`
Hence, conductivity of a solution is defined as the conductance of a conductor of 1 cm length and having 1 sq. cm as the area of cross section. Alternatively, it may be defined as conductance of one centimtre cube of the solution of the electrolyte. Molar conductivity of a solution at a dilution V is the conductance of all the ions produced from 1 mole of the electrolyte dissolved in `Vcm^(3)` of the ions produced by `wedge_(m)`
`wedge_(m) = KV`
Variation of conductivity and molar conductivity with concentration: Conductivity always decreases with decrease in concentration, for both weak and strong electrolytes. Because the number of ions per unit volume that carry the current in a solution decreases on dilution.
Molar conductivity vs for acetic acid (weak electrolyte) and potassium Chloride (strong electrolyte) in aqueous solutions Molar conductivity increases with decrease in concentration. Because that total volume, V, of solution containing one mole of electrolyte also increases. It has been found that decrease in on dilution of a solution is more than compensated by increase in its volume.