Question

The electric conduction of a salt solution in water depends on the : (a) Size of its molecules (b) Shape of its molecules (c) Size of solvent molecules (d) Extent of its ionization

Short answer

The electric conduction of a salt solution in water primarily depends on the extent of its ionization.

Step-by-step solution

Understanding the Concept

The electric conduction of a salt solution in water is the ability of the solution to conduct electricity. This property is largely influenced by the presence of ions in the solution. The more ions available, the better the conduction. Ions are charged particles that result from the dissociation of salt molecules in the solvent.

Analyzing the Options

The size and shape of the solute (salt) and solvent (water) molecules do not significantly affect the solution's conductivity. Instead, the ability of the salt to dissociate into ions in solution, which is termed ionization, is the determining factor for conducting electricity.

Identifying the Correct Option

The extent of ionization determines how many charge carriers (ions) are available in the solution to conduct electricity. Therefore, the correct answer is (d) Extent of its ionization.

Key concepts

Ionization in Electrolytes

The phenomenon of ionization in electrolytes is essential to understanding electric conduction in salt solutions. Ionization refers to the process where neutral molecules are converted into charged particles called ions. In the context of an electrolyte, which is a substance that produces an electrically conducting solution when dissolved in a polar solvent like water, this process is crucial.

When salts, acids, or bases dissolve in water, the molecules are often separated into their constituent ions, a process known as dissociation. For instance, table salt (sodium chloride, NaCl) dissociates into Na+ and Cl- ions. These ions are then free to move through the solution and carry electrical current. This movement of ions is what allows a solution to conduct electricity.

The degree of ionization will vary depending on the nature of the electrolyte and the solvent. Strong electrolytes, like common table salt, completely dissociate in water, producing a high concentration of ions, which results in good electrical conductivity. Weak electrolytes only partially dissociate, yielding fewer ions and consequently lower conductivity.

Electrical Conductivity in Solutions

Electrical conductivity in solutions is a measure of a solution's ability to conduct electricity. It is dependent on the presence of ions - charged particles that can move and carry an electric charge through the solution. When an electric voltage is applied to such a solution, the ions will migrate towards the oppositely charged electrode, resulting in an electric current.In a salt solution, conductivity is primarily governed by the concentration and mobility of the ions present. The higher the ion concentration, the greater the solution’s ability to conduct electricity. The mobility of these ions is affected by factors such as the temperature of the solution and the viscosity of the solvent. Increased temperature usually leads to higher ion mobility and hence better conductivity, while higher viscosity tends to impede the movement of ions, reducing conductivity.For teaching purposes, it's helpful to illustrate this concept with practical examples. A simple experiment involves measuring the conductivity of different salt solutions with a conductivity meter, allowing students to see real-time changes in conductivity with varying concentrations or types of salts.

Dissociation of Salts

The dissociation of salts is a critical concept when it comes to the electric conduction of salt solutions. Dissociation refers to the process whereby salt molecules separate into ions when dissolved in a solvent such as water. This occurs because the polar water molecules are able to stabilize the charged particles, allowing them to separate from the solid salt structure and move freely in solution.

For example, when NaCl dissolves in water, the Na+ cations and Cl- anions get detached from the ionic lattice of the salt crystal. These ions are now free to move in the water. The ease with which a salt dissociates is influenced by factors like the ionic bond strength in the salt and the dielectric constant of the water. Strong ionic bonds make dissociation more difficult, leading to fewer ions in solution and reduced conductivity. Conversely, salts with weaker ionic bonds dissociate more readily, increasing the number of charge carriers available.

To improve students' understanding of this concept, it is helpful to discuss the differences between strong, weak, and non-electrolytes, in relation to their dissociation properties and subsequent impact on the electrical conductivity of their solutions.