Table of Contents
In general, the conductance of a volume of a solution comprising one equivalent weight of dissolved substance when placed between two parallel electrodes 1 cm apart and large enough to contain the entire solution is defined as the conductance of an electrolyte. Λ has never been directly determined but is calculated from a specific conductance. Only when C is the concentration per cubic centimetre, then 1000/C is the volume containing one equivalent of the solute. Because Ls is the conductance of a centimetre cube of the solution, 1000/C cc, and Λ thus will be:
Equivalent conductance at infinite dilution
Once ionisation increases, so do the value of equivalent conductance as the solution dilutes.
At a constant temperature, for example, if we take two different solutions with different concentrations, the solution with a strong electrolyte has a higher conductance than the solution with a weak electrolyte. Even so, there is a point at which further dilution in either or both of the solutions is no longer possible, implying that it has no effect on the concentration of the solution. The idea of where dilution ends is known as infinite dilution.
Thereby, infinite dilution is defined as the state in which no further concentration can be obtained in a solution with any amount of dilution because it already contains the maximum amount of solvent possible. At this point of infinite dilution, all of the ions have been completely dissociated.
Kohlrausch’s Law
Kohlrausch’s Law explains the state of infinite dilution. As per this law, the sum of the equivalent conductances of all the anions and cations present in any solution is equal to the equivalent conductance of an electrolyte at infinite dilution of the same solution.
Factors Affecting Equivalent Conductivity
- Since the extent of ionisation increases with increasing temperature, so does the conductance of an electrolyte solution.
- All the strong electrolytes undergo complete ionisation and thus have higher conductivities due to the greater number of ions produced. But, weak electrolytes are partially ionised and thus have low conductivities in their solutions.
- When an ion’s size increases, its mobility decreases and its conductivity decreases.
- Because of the nature of the solvent and its viscosity, ionic mobility is reduced in more viscous solvents. The conductivity decreases as a result.
- The specific conductance increases with increasing solution concentration as the number of ions per unit volume increases.
- Although, because the extent of ionisation increases with decreasing concentration (i.e. dilution), so do equivalent conductivity and molar conductance.
FAQs
What is Equivalent Conductance?
The equivalent conductance of an electrolyte has been described as the conductance of a volume of solution containing one equivalent weight of dissolved substance when placed between two parallel electrodes 1 cm apart and large enough to hold the entire solution between them.
What is molar conductance?
The molar conductivity of a solution has been calculated by dividing the conductivity of an electrolyte solution by its molar concentration. The strength of conductivity of the ions produced in a solution when only one mole of an electrolyte is dissolved in it is referred to as molar conductance.
