Why is it not possible to obtain limiting molar conductivity graphically for a weak electrolyte.

Answer

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Table of Contents
Molar conductivity
Variation of Molar Conductivity
Frequently Asked Questions
Define molar conductivity.
How does molar conductivity depend on temperature?
Does molar conductivity vary with dilution? How?
Difference between conductivity and specific conductivity.

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Variation of Molar Conductivity

For strong electrolytes, the molar conductivity increases slowly with the dilution. The plot between the molar conductivity and c1/2 is a straight line having y-intercept equal to Ë°m. The value of limiting molar conductivity, Ë°m can be determined from the graph or with the help of Kohlrausch law. The general equation for the plot is given as:

Ʌm = Ë°m -Ac1/2

Where -A is a constant equal to the slope of the line. For a given solvent, the value of “A” depends on the type of electrolyte at a particular temperature.

For weak electrolytes, the graph plotted between molar conductivity and c1/2 (where c is the concentration) is not a straight line. Weak electrolytes have lower molar conductivities and lower degree of dissociation at higher concentrations which increases steeply at lower concentrations. Therefore, limiting molar conductivity, Ë°m cannot be obtained by extrapolation of molar conductivity to zero concentration. Hence, we use Kohlrausch’s law of independent migration of ions for determining to limit molar conductivity, Ë°m of weak electrolytes.

For a detailed discussion on the variation of molar conductivity with the concentration of electrolyte, download BYJU’S – The Learning App.

Frequently Asked Questions

Define molar conductivity.

The conducting power of all the ions which is produced by one mole of an electrolyte and dissolving it in the solution.

How does molar conductivity depend on temperature?

As temperature increases, the molar conductivity also increases.

Does molar conductivity vary with dilution? How?

Yes, molar conductivity varies with dilution. It increases with dilution.

Difference between conductivity and specific conductivity.

Specific conductance also termed as conductivity, specific electrical conductance or electrical conductivity is an estimate of the ability of water to conduct electricity.