Molar Conductivity

Molar (or Equivalent) Conductivity

Since conductivity of electrolyte solutions is a function of concentration, comparison of the conductivities of different electrolytes using a common reference point in preferred. This is useful when concentration is taken into account.

The concept of equivalent conductivity, now called molar conductivity, was introduced by Kohlrausch. It is given the symbol _m (lambda) and the subscript m signifies molar. Molar conductivity was introduced so that different electrolytes could be compared directly, eliminating variations in conductance due to varying amounts of electrolyte. Molar conductivity is the conductivity of a volume of solution containing one mole of the electrolyte when placed between electrodes 1cm apart.

Molar conductivity is defined by:

_m =K/C                                                                                                                        (8)

Where K is the specific conductivity and C is the concentration.