Kohlrausch Law || Electrochemistry || Molar Conductivity || Equivalent Conductivity | CSIR-NET

Chemistry Untold

24 Aug 202136:28

EducationalLearning

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TLDRThe video script delves into the concept of electrolyte dissociation and its impact on molar conductivity, particularly at infinite dilution. It explains how the number of ions from a fixed amount of electrolyte contributes to the electrolyte's equivalent conductance, independent of the associated ions. The script introduces the molar conductivity formula, discusses the application of Cholera's law to strong electrolytes, and illustrates how to calculate molar conductivity using the lambda notation. The discussion also touches on the degree of dissociation and its mathematical representation, providing a comprehensive understanding of electrolyte behavior in solution.

Takeaways

🔬 The concept of molar conductivity and its formula, which is conductivity divided by concentration, is discussed in the script.
🧪 The script introduces the idea of molar conductivity at infinite dilution and its relation to the number of ions produced by an electrolyte.
📚 It is explained that each ion contributes to the equivalent conductance of an electrolyte, regardless of the nature of the electrolyte.
🌐 The summation of contributions from constituent ions gives the equivalent conductance at infinite dilution for any electrolyte.
🔍 The script mentions the use of the Kohlrausch's law, which is applicable to strong electrolytes, to predict molar conductivity at infinite dilution.
📈 The concept of normality and its relation to molarity is briefly touched upon, with a formula for molar conductivity in terms of normality.
🧷 The script provides an example of calculating molar conductivity for AlCl3 at infinite dilution, using lambda not values for ions.
🔑 The formula for the degree of dissociation (alpha) is given, relating it to the concentration and the conductivity of the solution.
📊 The script discusses the graphical representation of the relationship between lambda not upon lambda and the concentration of the solution.
📝 The importance of understanding the formula for lambda not upon lambda, and its relation to the dissociation constant (Ka), is emphasized.
🎓 The script seems to be part of an educational discussion or lecture on electrolyte conductance and related chemical concepts.

Q & A

What is the relationship between the number of moles of an electrolyte and the number of ions it produces?
-The number of moles of an electrolyte is fixed, but the number of ions it produces can vary depending on its dissociation. Each mole of electrolyte can produce a different number of ions, which is represented by the sum of x times a^+ and y times b^-, where x and y are the stoichiometric coefficients of the cation and anion, respectively.
What does the term 'lambda' represent in the context of electrolyte dissociation?
-In the script, 'lambda' represents the degree of dissociation of an electrolyte, which is a measure of how completely an electrolyte dissociates into its constituent ions in solution.
What is meant by 'molar conductivity at infinite dilution'?
-Molar conductivity at infinite dilution refers to the conductivity of a solution when the concentration of the electrolyte is so low that it approaches zero. It is a theoretical value used to understand the intrinsic conductivity of the ions in the absence of any interactions between them.
How is the equivalent conductance of an electrolyte related to its constituent ions?
-The equivalent conductance of an electrolyte at infinite dilution is the sum of the individual contributions of its constituent ions. Each ion contributes a definite amount towards the equivalent conductance of the electrolyte, irrespective of the nature of the electrolyte or the concentration.
What is the significance of the formula λ° = x * λ°(A+) + y * λ°(B-) in the context of molar conductivity?
-This formula is used to calculate the molar conductivity at infinite dilution (λ°) of an electrolyte by summing the contributions of its constituent ions (A+ and B-), where x and y are the number of moles of each ion produced per mole of electrolyte.
What is normality and how does it relate to molarity?
-Normality is a measure of concentration that expresses the amount of substance in terms of equivalents per unit volume of solution. It is related to molarity by the formula: normality = molarity * equivalent weight. The script suggests that while there is a known relation between molarity and normality, the user is asking if a similar relation can be established for molar conductivity.
How is molar conductivity calculated?
-Molar conductivity is calculated using the formula: conductivity / concentration * 100. This formula allows for the calculation of the conductivity per unit concentration, which is useful for comparing the conductive properties of different electrolytes.
What is the molar conductivity of AlCl3 at infinite dilution?
-The molar conductivity of AlCl3 at infinite dilution is calculated using the formula λ° = λ°(Al3+) * 1 + λ°(Cl-) * 3, where λ° represents the molar conductivity at infinite dilution for each ion.
What is the significance of the term 'association' in the context of electrolyte solutions?
-Association refers to the process where ions in a solution come together to form ion pairs or larger complexes, reducing the number of free ions and thus affecting the conductivity of the solution. The script mentions that the formula used is applicable only for strong electrolytes that do not associate significantly.
How can the molar conductivity of a mixture of electrolytes be calculated?
-The molar conductivity of a mixture of electrolytes can be calculated by summing the individual contributions of the constituent ions, taking into account their dissociation and the degree of association, if any.
What is the role of Kohlrausch's law in calculating molar conductivity at infinite dilution?
-Kohlrausch's law is used to predict the molar conductivity at infinite dilution for strong electrolytes. It allows for the calculation of the molar conductivity of an electrolyte by considering the contributions of its constituent ions and their degree of dissociation.
What is the formula for calculating the degree of dissociation (α) of an electrolyte?
-The degree of dissociation (α) can be calculated using the formula: α = (λ / λ°) * (1 + λ / K_a), where λ is the observed molar conductivity, λ° is the molar conductivity at infinite dilution, and K_a is the acid dissociation constant.
How can the molar conductivity at infinite dilution be correlated with the degree of dissociation?
-The correlation between molar conductivity at infinite dilution and the degree of dissociation can be established using the formula: λ° / λ = 1 + λ * concentration / K_a, which shows the relationship between the observed molar conductivity, the degree of dissociation, and the concentration of the electrolyte.

Outlines

00:00

🔬 Electrolyte Molarity and Ion Conductivity

The first paragraph discusses the concept of electrolyte molarity and its relation to the number of ions produced. It emphasizes that at a fixed number of moles, the number of ions generated is also fixed. The paragraph introduces the concept of molar conductivity at infinite dilution, which is a logarithmic scale, and highlights that each ion contributes to the electrolyte's equivalent conductance regardless of the electrolyte it is associated with.

08:25

🔍 Molar Conductivity Formula and Relations

This paragraph delves into the molar conductivity formula at infinite dilution, explaining how it is derived from the sum of contributions of the constituent ions. It discusses the concept of normality and how it relates to molarity, and then explores the formula for molar conductivity, which is conductivity divided by concentration multiplied by 100. The paragraph also touches on the molar conductivity of specific electrolytes like AlCl3 at infinite dilution.

13:47

🧪 Calculating Molar Conductivity of AlCl3

The third paragraph focuses on the calculation of molar conductivity for AlCl3 at infinite dilution. It outlines the formula involving lambda not of aluminum ions and chloride ions, and discusses the concept of molality and molarity in relation to molar conductivity. The paragraph also mentions the dissociation of electrolytes and the use of the formula to calculate the molar conductivity of AlCl3.

19:37

📚 Molar Conductivity of Weak Electrolytes

This paragraph explores the molar conductivity of weak electrolytes, such as sodium acetate and NaCl, and mentions the use of Cholera's law for strong electrolytes to predict molar conductivity at infinite dilution. It discusses the concept of lambda not and how it can be used to calculate the molar conductivity of different electrolytes, including HCl and CH3COONa.

26:20

🔧 Cholera's Law and Degree of Dissociation

The fifth paragraph discusses Cholera's law, which is applicable to strong electrolytes, and how it can be used to calculate the maximum molar conductivity at infinite dilution. It introduces the concept of the degree of dissociation and relates it to the formula for the degree of dissociation, which involves the concentration and the dissociation constant (Ka).

32:39

📉 Graph Interpretation and Lambda Notations

The final paragraph discusses the interpretation of a graph related to electrolyte dissociation, focusing on the slope and its relation to lambda not. It explains the formula for lambda not in terms of the dissociation constant and concentration, and how it can be used to interpret the graph. The paragraph also touches on the potential questions that could arise from this topic in exams.

Mindmap

Keywords

💡Electrolyte

An electrolyte is a substance that dissociates into ions when dissolved in a solvent, typically water, and thus becomes capable of conducting electricity. In the video's context, the focus is on the behavior of electrolytes in solution, particularly how their ionization affects their conductivity. The script mentions taking 'one mole of electrolyte' to discuss molar conductivity.

💡Moles

Moles represent the amount of a substance, and it is a fundamental concept in chemistry for quantifying reactants and products in chemical reactions. The script refers to 'the number of moles of electrolyte' to establish a basis for discussing the relationship between the quantity of electrolyte and the number of ions produced.

💡Ions

Ions are atoms or molecules that have lost or gained electrons, resulting in a net electrical charge. The video discusses how the number of ions is related to the moles of electrolyte and their contribution to the conductivity of a solution, as indicated by phrases like 'the number of ions be fixed'.

💡Molar Conductivity

Molar conductivity is a measure of a solution's ability to conduct electricity, expressed in terms of the number of moles of solute. The script introduces the concept with the formula 'conductivity divided by concentration, multiplied by 100', highlighting its importance in understanding the behavior of electrolytes at various concentrations.

💡Infinite Dilution

Infinite dilution refers to a hypothetical state where the concentration of a solute approaches zero. The video discusses the molar conductivity at infinite dilution, which is a standard measure of an ion's ability to conduct electricity in an ideal, undisturbed state, as seen in the phrase 'molar conductivity at infinite dilution'.

💡Equivalent Conductance

Equivalent conductance is the conductance contributed by one equivalent of an ion, which is the amount of substance that will carry one unit of electric charge. The script mentions that 'each ion makes a definite contribution towards equivalent conductance', emphasizing the individual impact of different ions on the overall conductivity of an electrolyte solution.

💡Cholera's Law

Cholera's Law is a principle used to predict the molar conductivity of strong electrolytes at infinite dilution. The script refers to this law to explain how the molar conductivity of certain electrolytes can be calculated, particularly with the formula 'lambda naught upon lambda will be equal to 1 plus lambda upon lambda naught into concentration upon k a'.

💡Normality

Normality is a measure of concentration defined as the number of equivalents of a solute per liter of solution. The script briefly mentions 'we speak in terms of normality now', indicating an alternative way to express concentration that is particularly useful for solutions where reactions involve the transfer of a known number of moles of electrons.

💡Molality

Molality is the measure of the number of moles of solute per kilogram of solvent. The script uses the term in the context of calculating molar conductivity, as indicated by 'molarity molality, divided by 3', to show an alternative concentration measure that is independent of the volume of the solution.

💡Degree of Dissociation

The degree of dissociation is the fraction of molecules of a solute that ionize in a solution. The script discusses this concept in relation to the formula 'k will be equal to alpha into c upon 1 upon alpha minus 1', where 'alpha' represents the degree of dissociation, and it is used to understand the extent to which an electrolyte ionizes in solution.

💡Slope

In the context of the script, slope refers to the gradient of a graph, which is used to visualize the relationship between variables. The script mentions 'what will be the slope' in relation to a graph where the variable starts from a cutoff on the y-axis, indicating the importance of slope in understanding the graphical representation of electrolyte behavior.

Highlights

The concept of molar conductivity and its relation to the number of ions produced by an electrolyte is discussed.

Explains the logarithmic relationship between molar conductivity and ionic strength.

Introduction of the infinite dilution formula for molar conductivity.

Each ion contributes a definite amount to the equivalent conductance of an electrolyte.

Molar conductivity at infinite dilution is the sum of contributions from its constituent ions.

Conductivity of ions at infinite dilution is constant and does not depend on the nature of the electrolyte.

Molarity and normality are related, and their impact on molar conductivity is discussed.

The formula for molar conductivity is presented, relating conductivity to concentration and equivalent conductivity.

Molar conductivity of AlCl3 at infinite dilution is calculated using the lambda notation.

The concept of association in electrolytes and its effect on molar conductivity is explained.

Cholera's law is introduced for calculating molar conductivity at infinite dilution for strong electrolytes.

Molar conductivity values for various strong electrolytes are provided and their 100% dissociation is noted.

The degree of dissociation and its formula are discussed in the context of molar conductivity.

The relationship between molar conductivity and the degree of dissociation is mathematically formulated.

The slope of the graph representing the relationship between molar conductivity and concentration is identified.

The transcript mentions potential exam questions related to conductivity in CSIR and GATE.

The importance of understanding the lambda notation and its application in electrolyte conductivity is emphasized.

The transcript concludes with a musical interlude, indicating a pause or conclusion to the discussion.

Transcripts

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Related Tags

Electrolyte Dissociation Molar Conductivity Chemistry Principles Infinite Dilution Equivalent Conductance Ionic Conductance Cholera's Law Strong Electrolytes Concentration Formula Dissociation Degree