Question

State whether each of the following statements is true or false. Justify your answer in each case. (a) Electrolyte solutions conduct electricity because electrons are moving through the solution. (b) If you add a nonelectrolyte to an aqueous solution that already contains an electrolyte, the electrical conductivity will not change.

Short answer

Statement (a) is false. Electrolyte solutions conduct electricity due to the movement of ions, not electrons. Ions are charged particles formed when a substance, such as a salt, dissociates in the solution, enabling the conduction of electric current. Statement (b) is generally true. Adding a nonelectrolyte to an aqueous solution containing an electrolyte typically does not change the electrical conductivity. This is because nonelectrolytes don't produce charged particles when dissolved, thus not affecting the free movement of ions in the electrolyte solution.

Step-by-step solution

Statement (a) - Analysis

To confirm or invalidate this statement, we need to recall the definition of electrolyte solutions and how they conduct electricity.

Statement (a) - True or False?

The given statement is false. Electrolyte solutions conduct electricity because of the movement of ions, not electrons.

Statement (a) - Justification

An electrolyte solution is formed when a substance, usually a salt, dissociates into its constituent ions, such as cations and anions. These charged particles (ions) are free to move within the solution, enabling the solution to conduct electricity. Electrons themselves do not move through the solution; it's the movement of ions that allows the conduction of electric current.

Statement (b) - Analysis

For this statement, we need to think about what happens when we add a nonelectrolyte to a solution containing an electrolyte and how that would affect the electrical conductivity.

Statement (b) - True or False?

The given statement is generally true. Adding a nonelectrolyte to an aqueous solution that already contains an electrolyte typically does not change the electrical conductivity.

Statement (b) - Justification

A nonelectrolyte is a substance that, when dissolved in water, does not dissociate into ions, meaning it doesn't produce charged particles. When we add a nonelectrolyte to an already conductive electrolyte solution, it will effectively only dilute the electrolyte and decrease the concentration of ions in the solution. However, it won't change the ions' ability to move freely within the solution and conduct electricity. So, the electrical conductivity generally remains constant in this case. Note that in rare cases where the added nonelectrolyte has a significant impact on the electrolyte's ion dissociation or mobility, the electrical conductivity may experience a slight change. But for typical nonelectrolytes, the change in conductivity is negligible.

Key concepts

Ion movement

In the context of chemistry, ion movement is a crucial concept for understanding how solutions conduct electricity. Ions are charged particles that arise when a compound, like a salt, dissolves in water and separates into its constituent ions. These ions can be either positively charged (cations) or negatively charged (anions).
When an electrolyte is dissolved in water, the ions become dispersed throughout the solution and are free to move. It is this movement of ions that allows the solution to conduct an electric current.

• Cations move towards the negatively charged electrode, known as the cathode.
• Anions move towards the positively charged electrode, known as the anode.

This orderly movement of ions under the influence of an electric field results in the flow of electric current through the solution.
While electrons move in wires to create electricity, it is the ions that carry the charge through liquid solutions.

Electrical conductivity

Electrical conductivity in solutions refers to the ability of a liquid to carry an electric current. This property depends heavily on the presence of free ions within the solution.
Solutions with a high concentration of dissolved ions are typically highly conductive. This is because more ions are available to carry the charge through the solution. On the other hand, solutions with few or no ions show little to no conductivity.
Factors affecting conductivity include:

• Concentration of ions: More ions result in higher conductivity.
• Type of ions: Ions with higher charges and smaller sizes typically result in greater conductivity.
• Temperature of the solution: Higher temperatures can increase ion movement, thus increasing conductivity.

In summary, the electrical conductivity of a solution provides insight into its ion content and can be a powerful indicator of the solution's overall chemical composition.

Nonelectrolyte

A nonelectrolyte is a type of compound that, when dissolved in water, does not dissociate into ions. As a result, nonelectrolyte solutions do not conduct electricity, due to the absence of charged particles to support the flow of electric current.
Examples of nonelectrolytes include sugar, ethanol, and other molecular compounds that remain as neutral molecules when dissolved.
Key characteristics of nonelectrolytes include:

• They consist of covalent bonds, which are held together by shared electrons.
• Upon dissolving, these substances do not produce ions in the solution.

When a nonelectrolyte is added to a solution containing an electrolyte, the nonelectrolyte does not alter the initial conductivity significantly. This is because it neither introduces additional ions nor interferes with the existing ion movement.
Thus, solutions with nonelectrolytes remain poor conductors unless other ions are present.