Problem 7 - Chemistry The Molecular Nature of Matter

Question

Why is an electrolyte able to conduct electricity while a nonelectrolyte cannot?

Step-by-Step Solution

Answer

An electrolyte can conduct electricity because it dissociates into free ions that carry charges in solution. A nonelectrolyte cannot conduct electricity as it remains as neutral molecules.

Step 1: Understanding Electrolyte and Nonelectrolyte

Understand that the key difference between an electrolyte and a nonelectrolyte is that an electrolyte can split into ions when dissolved in water. These ions carry electric charge, which allows them to conduct electricity. In contrast, a nonelectrolyte dissolves as molecules that do not separate into ions and therefore does not conduct electricity.

Step 2: Dissociation of Electrolytes

Acknowledge that electrolytes are substances that, when dissolved in water, dissociate into positively and negatively charged ions. These ions move freely in solution, which allows them to carry electrical charges and thus conduct electricity.

Step 3: Molecular Solution of Nonelectrolytes

Recognize that nonelectrolytes do not split into ions when dissolved; they form a solution of neutral molecules. Without free ions to carry an electrical charge, such a solution cannot conduct electricity.

Key Concepts

Electrolyte and Nonelectrolyte

Understanding the distinction between electrolytes and nonelectrolytes is crucial when studying their conductivity. Electrolytes are substances that produce ions in solution, which are carriers of electrical current. A common example of an electrolyte is table salt (sodium chloride), which, when dissolved in water, separates into sodium (Na⁺) and chloride (Cl^-) ions.

A nonelectrolyte, on the other hand, dissolves in water to form a solution of intact, neutral molecules. These molecules do not provide ions and, as a result, do not support the movement of electrical charge. Glucose, for instance, dissolves as whole molecules and is a typical example of a nonelectrolyte.

Understanding this fundamental difference helps clarify why solutions of electrolytes are able to conduct electricity, while solutions of nonelectrolytes cannot. It is the presence or absence of ions that creates this distinction.

Ion Dissociation

The process of ion dissociation is essential for the conductivity of an electrolyte. When an electrolyte dissolves in water, it undergoes a chemical process where the compound separates into its constitutive ions. This dissociation occurs because the polar nature of water molecules creates an environment that can stabilize ions, allowing them to separate from the solid structure of the compound.

For instance, when the ionic compound sodium chloride is dissolved in water, it dissociates into sodium (Na⁺) and chloride (Cl^-) ions. These ions are then free to move about in the solution, turning it into a conductor of electricity. The extent to which a substance dissociates determines its strength as an electrolyte: strong electrolytes fully dissociate into ions, while weak electrolytes only partially dissociate.

Electrical Charge in Solutions

The concept of electrical charge in solutions underpins the ability of a substance to conduct electricity. When electrolytes dissolve and dissociate into ions, they release positive and negative charged particles into the solution.

The movement of these charges is what constitutes an electric current. In an electrolytic solution, positively charged ions, known as cations, and negatively charged ions, known as anions, migrate towards electrodes with opposite charges when an electrical potential is applied. This flow of ions is disrupted in a solution of nonelectrolytes, as there are no charged particles to move toward the electrodes. Conductivity in solutions is, therefore, a direct result of the presence of mobile, charged ions, which are absent in solutions of nonelectrolytes.