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A topic from the subject of Contributions of Famous Chemists in Chemistry.

  • 11 months ago
  • 6 min read
Svante Arrhenius's Theory of Electrolytic Dissociation
Introduction:

Svante Arrhenius proposed the theory of electrolytic dissociation in 1887. This theory explains the behavior of electrolytes, substances that conduct electricity when dissolved in a solution.

Basic Concepts:

Electrolytes are substances that ionize in solution. Ions are charged atoms or molecules.

Electrolytes can be strong or weak. Strong electrolytes ionize completely in solution.

Weak electrolytes ionize partially in solution.

Equipment and Techniques:

Conductivity meter: Measures the electrical conductivity of a solution.

Electrometer: Measures the electrical potential difference between two electrodes.

Voltaic pile: A simple voltaic cell used to demonstrate the theory of electrolytic dissociation.

Types of Experiments:

Conductivity measurements: The conductivity of a solution is proportional to the number of ions it contains.

Electromotive force (EMF) measurements: The EMF of a voltaic cell is proportional to the free energy change of the electrochemical reaction.

Data Analysis:

Conductivity measurements can be used to determine the molar mass of an unknown substance.

EMF measurements can be used to determine the equilibrium constant for an electrochemical reaction.

Applications:

The theory of electrolytic dissociation is used to explain many phenomena, including:

  • The behavior of batteries
  • The corrosion of metals
  • The mechanism of neutralization reactions
Conclusion:

Svante Arrhenius's theory of electrolytic dissociation is a valuable tool for understanding the behavior of electrolytes and their many applications. From understanding the behavior of batteries to explaining the mechanism of neutralization reactions, it provides a foundation for further research and development in the field of physical chemistry.

Svante Arrhenius's Theory of Electrolytic Dissociation

Svante Arrhenius proposed his theory of electrolytic dissociation in 1887, which revolutionized the understanding of electrolytes and solutions in chemistry. Here are the key points and main concepts:

Key Points:
  • Electrolytes: Arrhenius defined electrolytes as substances that, when dissolved in water, dissociate into ions, which are electrically charged particles.
  • Ionic Dissociation: According to Arrhenius's theory, electrolytes dissociate into positive ions (cations) and negative ions (anions) when dissolved in water. This process is known as ionic dissociation.
  • Degree of Dissociation: The degree of dissociation refers to the extent to which an electrolyte dissociates into ions. Strong electrolytes dissociate completely, while weak electrolytes dissociate partially.
  • Electrical Conductivity: The presence of ions in solution allows for the conduction of electricity. The higher the degree of dissociation, the higher the electrical conductivity of the solution.
  • Neutralization Reactions: Arrhenius's theory explained the process of neutralization reactions between acids and bases. When an acid and a base are mixed, their ions react to form water and a salt. For example, the reaction between HCl (hydrochloric acid) and NaOH (sodium hydroxide) produces NaCl (sodium chloride) and H₂O (water).
Main Concepts:
  • Ions: Ions are electrically charged particles formed when an atom or molecule gains or loses electrons. Cations have a positive charge, while anions have a negative charge.
  • Solution: A solution is a homogeneous mixture of two or more substances. In an electrolytic solution, the solute (electrolyte) dissociates into ions, while the solvent (usually water) remains intact.
  • Electrolysis: Electrolysis is the process by which an electric current is passed through an electrolyte solution, causing the ions to migrate towards the oppositely charged electrodes, resulting in chemical reactions at the electrodes.
  • pH and Acidity: Arrhenius's theory provided a framework for understanding the concept of pH and acidity. Acids are substances that produce hydrogen ions (H+) when dissolved in water, while bases produce hydroxide ions (OH-).

Arrhenius's theory of electrolytic dissociation was a groundbreaking concept that laid the foundation for modern electrochemistry and our understanding of solutions. It revolutionized the field of chemistry and continues to be a fundamental theory in the study of electrolytes and their properties.

Svante Arrhenius's Theory of Electrolytic Dissociation
Experiment:
Objective: To demonstrate the electrolytic dissociation of salts in water and to measure the conductivity of the resulting solutions. Materials:
  • Distilled water
  • Sodium chloride (NaCl)
  • Potassium chloride (KCl)
  • Calcium chloride (CaCl2)
  • Conductivity meter
  • Beaker
  • Magnetic stirrer
  • Thermometer
Procedure:
  1. Prepare 0.1 M solutions of NaCl, KCl, and CaCl2 by dissolving 0.5844 g of NaCl, 0.7455 g of KCl, and 1.1098 g of CaCl2 in 100 mL of distilled water, respectively.
  2. Rinse the conductivity meter probe with distilled water and dry it thoroughly.
  3. Connect the conductivity meter to a power source and turn it on.
  4. Place a beaker of distilled water on the magnetic stirrer and adjust the speed to a moderate setting.
  5. Immerse the conductivity meter probe into the beaker of distilled water and record the conductivity reading.
  6. Add about 1 mL of the NaCl solution to the beaker of distilled water and stir for a few minutes.
  7. Record the conductivity reading again.
  8. Repeat steps 6 and 7 for the KCl and CaCl2 solutions.
  9. Record the temperature of each solution using a thermometer.
Observations:
  • The conductivity of the distilled water is very low.
  • The conductivity of the salt solutions increases as the concentration of the salt increases.
  • The conductivity of the salt solutions also increases as the temperature increases.
  • The conductivity of the CaCl2 solution is higher than that of the NaCl and KCl solutions at the same concentration.
Conclusion: The results of this experiment support Svante Arrhenius's theory of electrolytic dissociation. When a salt is dissolved in water, it dissociates into its constituent ions. These ions are free to move around in the solution, which allows them to conduct electricity. The conductivity of a salt solution is a measure of the concentration of ions in the solution. The higher the concentration of ions, the higher the conductivity. The conductivity of a salt solution also increases as the temperature increases. This is because the higher the temperature, the more ions are able to escape from the crystal lattice of the salt and dissolve into the water. The conductivity of the CaCl2 solution is higher than that of the NaCl and KCl solutions at the same concentration because CaCl2 dissociates into more ions (3 ions) compared to NaCl and KCl (2 ions each). NaCl and KCl are strong electrolytes, meaning they dissociate completely in water. The difference in conductivity is due to the difference in the number of ions produced upon dissociation. This experiment demonstrates the importance of electrolytic dissociation in chemistry. Electrolytic dissociation is responsible for the conductivity of salt solutions and for many other important properties of these solutions.

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