Chemistry is a fascinating subject that reveals some very interesting principles governing the behaviour of substances around us. One such principle is Kohlrausch’s Law which helps understand the nature of electrolytes and their conductivity in solutions. Kohlrausch’s Law is not only important for class 12 studies but also for various entrance exams including NEET and JEE. It is a topic that is frequently covered in the chemistry syllabus for these exams. In this article, we have explained Kohlrausch’s Law in simple terms, explaining its definition, formula, applications, and other crucial information related to it. You may also download the explanation of Kohlrausch’s Law in PDF so as to revise it at your convenience.
What is Kohlrausch’s Law?
The Kohlrausch Law, named after the German chemist Friedrich Kohlrausch, is a principle that helps us understand how the conductivity of an electrolyte solution depends on the concentration of ions within it. In other words, it describes the relationship between the conductivity of a solution and the concentration of its ions.
Definition:
Kohlrausch's law states that the limiting molar conductivity of an electrolyte can be represented as the sum of the individual contributions of the anions and cations of the electrolyte.
| Know More! Equivalent conductivity is defined as the conductivity of one gram equivalent of an electrolyte dissolved in 1 litre solution. It is denoted by the symbol Λ. Its SI unit is Scm2equiv-1 (siemens centimetre square per equivalent). Infinite dilution is a hypothetical condition in which the concentration of an electrolyte is zero. At infinite dilution, all of the ions are completely dissociated from each other and there is no interaction between them. |
Formula for Kohlrausch's law
The mathematical formula for Kohlrausch's law is as follows:
Λ∞ = Λ∞+ + Λ∞−
where:
Λ∞ = Equivalent conductivity of the electrolyte at infinite dilution
Λ∞+ = Equivalent conductivity of the cation at infinite dilution
Λ∞− = Equivalent conductivity of the anion at infinite dilution
Applications
Kohlrausch's law has a number of important applications in chemistry, including:
- Determining degree of dissociation: The degree of dissociation of an electrolyte is the fraction of the electrolyte molecules that have dissociated into ions. Kohlrausch's law can be used to determine the degree of dissociation of an electrolyte by measuring its equivalent conductivity at different concentrations.
- Calculating limiting molar conductivity: The limiting molar conductivity of an electrolyte is the equivalent conductivity of that electrolyte at infinite dilution. It can be computed by adding the limiting molar conductivities of the individual ions in the electrolyte.
- Determining solubility of sparingly soluble salts: Kohlrausch's law can be used to determine the solubility of sparingly soluble salts by measuring the equivalent conductivity of the salt solution.
- Determining dissociation constant for weak electrolytes: Kohlrausch's law can be used to determine the dissociation constant for a weak electrolyte by measuring the molar conductivity or specific conductivity of the electrolyte at different concentrations.
| Download Kohlrausch Law Definition, Formula & Applications in PDF |
Also Check Boyle's Law Definition, Formula, Applications & More
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