Molar conductance is defined as the conducting power of all the ions produced by dissolving one mole of an electrolyte in a given volume of solution. It measures how well a solution can conduct electricity due to the presence of ions. The unit of molar conductance is typically expressed as ohm⁻¹ cm² mol⁻¹ (or siemens cm² mol⁻¹). Molar conductance (Λm\Lambda_m Λm) is related to the specific conductance (also called conductivity, κ\kappa κ) of the solution and the molarity (mmm) by the formula:
Λm=κ×1000m\Lambda_m =\frac{\kappa \times 1000}{m}Λm=mκ×1000
where κ\kappa κ is the specific conductance in ohm⁻¹ cm⁻¹ and mmm is the molar concentration in moles per liter. In summary:
- Molar conductance represents the total conductance of ions from one mole of electrolyte dissolved in solution.
- It increases with dilution because although specific conductance decreases, the volume containing one mole increases.
- The unit is ohm⁻¹ cm² mol⁻¹ or siemens cm² mol⁻¹.
This captures the ability of a solution containing one mole of electrolyte to conduct electricity when placed between electrodes one centimeter apart with a cross-sectional area large enough to contain that mole of electrolyte.
