4.1.2 Concept of Electrolytes and Electrolysis

Introduction

When an ionic compound is dissolved in water, it splits up into its positive and negative ions. These ions are capable of conducting electricity. Such compounds are referred to as electrolytes.

This section explains what electrolytes are, how they differ from non-electrolytes, and how electrolytic cells work.

Definition

Electrolytes: Substances that can conduct electricity when they are in a molten state or aqueous solution and undergo chemical changes.

Non-Electrolytes: A substance that cannot conduct electricity when dissolved in water or in the molten state.

Examples of Electrolytes: NaCl, KCl, HCl, NaOH, etc.

Examples of Non-Electrolytes: Urea, glucose, sucrose, benzene, etc.

In simple words:

• Electrolytes = substances that conduct electricity in molten or aqueous state and undergo chemical change.
• Non-electrolytes = substances that do not conduct electricity in molten or aqueous state.

Main Idea

• Ionic compounds split into ions when dissolved in water.
• These free ions conduct electricity.
• Such compounds are called electrolytes.
• Substances that do not conduct electricity are called non-electrolytes.
• Electrolysis is the process of using electrical energy to drive a chemical reaction.

Core Concept

Key point: Electrolytes conduct electricity because they contain free-moving ions in molten or aqueous state.

Detailed Explanation

What Happens When an Ionic Compound Dissolves in Water?

When an ionic compound is dissolved in water:

• The compound splits up into its positive and negative ions.
• These ions are free to move in the solution.
• The free-moving ions can carry electrical charge.
• This allows the solution to conduct electricity.

Example: When NaCl dissolves in water:

NaCl_(s) → Na⁺_(aq) + Cl^-_(aq)

The Na⁺ and Cl^- ions are free to move and conduct electricity.

What Happens When an Ionic Compound is Molten?

When an ionic compound is heated to its melting point:

• The rigid lattice structure breaks down.
• The ions become free to move.
• The molten salt can conduct electricity.

Example: Molten NaCl contains free Na⁺ and Cl^- ions that can carry electrical charge.

Why Non-Electrolytes Do Not Conduct Electricity

Non-electrolytes do not contain free ions. They exist as molecules in solution, not as ions. Since there are no free-moving ions, they cannot conduct electricity.

Example: Glucose dissolves in water as molecules, not ions:

C₆H₁₂O₆(s) → C₆H₁₂O₆(aq)

No ions are formed, so no electricity is conducted.

Summary Table

Intermediate Level

Electrolytes:

• Ionic compounds that split into ions in molten or aqueous state.
• The free ions conduct electricity.
• They undergo chemical changes during conduction.

Non-electrolytes:

• Substances that do not form ions in solution.
• They exist as molecules.
• They do not conduct electricity.

Key distinction:

• Electrolyte → free ions → conducts electricity.
• Non-electrolyte → molecules → does not conduct electricity.

Examples:

• Electrolytes: NaCl, KCl, HCl, NaOH
• Non-electrolytes: urea, glucose, sucrose, benzene

Important Points

• - Electrolytes = substances that conduct electricity in molten or aqueous state and undergo chemical changes.
• - Non-electrolytes = substances that do not conduct electricity in molten or aqueous state.
• - Electrolytes conduct electricity because they contain free-moving ions.
• - Non-electrolytes do not conduct electricity because they contain molecules, not ions.
• - Examples of electrolytes: NaCl, KCl, HCl, NaOH.
• - Examples of non-electrolytes: urea, glucose, sucrose, benzene.

Remember

• - Electrolytes conduct electricity in molten or aqueous state.
• - Non-electrolytes do not conduct electricity.
• - Electrolytes contain free ions.
• - Non-electrolytes contain molecules.
• - Examples of electrolytes: NaCl, KCl, HCl, NaOH.
• - Examples of non-electrolytes: urea, glucose, sucrose, benzene.

Common Mistakes

Quick Revision

Electrolytes: When an ionic compound is dissolved in water, it splits up into its positive and negative ions. These ions are capable of conducting electricity. Such compounds are referred to as electrolytes.

Substances that can conduct electricity when they are in a molten state or aqueous solution and undergo chemical changes.

• Non-Electrolytes:
• A substance that cannot conduct electricity when dissolved in water or in the molten state is called a non-electrolyte.

• Examples of Electrolytes:
• NaCl, KCl, HCl, NaOH, etc.

• Examples of Non-Electrolytes:
• Urea, glucose, sucrose, benzene, etc.

• Why Electrolytes Conduct Electricity:
• They contain free-moving ions that can carry electrical charge.

60-Second Revision

• Electrolytes = conduct electricity in molten/aqueous state.
• Non-electrolytes = do not conduct electricity.
• Electrolytes contain free ions.
• Non-electrolytes contain molecules.
• Examples of electrolytes: NaCl, KCl, HCl, NaOH.
• Examples of non-electrolytes: urea, glucose, sucrose, benzene.
• Free ions → conduct electricity.
• No free ions → no conduction.
• ⚠️ Warning: solid ionic compounds do not conduct electricity because their ions are not free to move.