(a) Define molar conductivity of a solution and explain how molar conductivity changes with change in concentration of solution for a weak and a strong electrolyte.
(b) The resistance of conductivity cell containing `0.001 M KCl` solution at `298 K` is `1500 omega`.
What is the cell constant if the conductivity of `0.001 MKCl` solution at `298 K` is `0.146 xx 10^(-3) S cm^(-1)`

Explanation

Molar conductivity of a solution at a given concentration is the conductance of the volume V of solution contaning is the conductance of the volume V of solution containing one mole of electrolyte keep between two electrodes with area of with area of cross section A and distance of unit length .
`A_(m) = (K xx 1000)/(C) S cm^(2) mol^(-1)`
Molar conductivity increases marginally with deacrease in concentration / increases in dilution for a strong electrolyte.
For weak electrolyte , increases steeply with decreases in concentration/ increases in dilution. This in accordance with Le Chatelier principle.
(b) `K = 1/rho xx l/A` or `K = 1/rhoxx G^(**)`.
`G^(**) = l/A` = Cell constant `rArr G^(**) = rho xx K`.
`= 1500 ohms xx 0.146 xx 10^(-3) ohm^(-1) cm^(-1)`.
`=1500 xx 0.146 xx 10^(-3)cm^(-1) = 219 xx 10^(-3) cm^(-1)`