🔬 What is Electrolysis? (Exam Definition)

Electrolysis is the chemical decomposition of an electrolyte (ionic compound molten or in aqueous solution) using direct electric current (DC).

Key terms you must memorize:

• Electrolyte: Substance that conducts electricity by mobile ions.
• Anode: Positive electrode where oxidation occurs.
• Cathode: Negative electrode where reduction occurs.
• Oxidation: Loss of electrons.
• Reduction: Gain of electrons.

👉 These definitions are repeatedly tested in O Level & IGCSE Chemistry definitions.

⚡ Ionic Theory & Electrolysis (Core Concept)

Electrolysis is based on the ionic theory. When an ionic compound melts or dissolves in water, it breaks into positive ions (cations) and negative ions (anions).

• Cations move to the cathode and are reduced.
• Anions move to the anode and are oxidized.

To master this topic, revise: Structure of Atom Notes and Reactivity Series.

🧪 Electrolysis of Molten Compounds (O Level & IGCSE)

Example: Electrolysis of molten lead(II) bromide

• Cathode reaction: Pb²⁺ + 2e⁻ → Pb
• Anode reaction: 2Br⁻ → Br₂ + 2e⁻

This concept links directly with Mole Concept & Stoichiometry and Prediction of Products.

💧 Electrolysis of Aqueous Solutions (Very Important)

In aqueous electrolysis, water competes with ions. You must remember:

• At cathode: hydrogen is usually produced (unless Cu²⁺, Ag⁺).
• At anode: oxygen is usually produced (unless halide ions present).

This topic is heavily tested in: IGCSE 0620 Past Papers and O Level 5070 Notes.

🧂 Electrolysis of Brine (NaCl Solution)

• Cathode: 2H₂O + 2e⁻ → H₂ + 2OH⁻
• Anode: 2Cl⁻ → Cl₂ + 2e⁻

Products: Chlorine gas, Hydrogen gas, Sodium hydroxide.

Applications include:

• Manufacture of bleach
• Soap and detergent industry
• PVC plastic production

📘 Download Free Chemistry Notes PDFs

• Electrolysis Notes PDF – Download
• Moles Notes PDF
• Redox Notes PDF
• Metals Notes PDF
• Acids, Bases & Salts PDF

🎥 Must-Watch Exam Videos

Mood Booster (Study Motivation)

O Level & IGCSE Chemistry Crash Course

IGCSE 0620 Solved Paper

O Level 5070 Solved Paper

Cations & Anions Identification Cheat Sheet

Periodic Table Hack Song

👨‍🏫 Teacher Profile

Professor Faisal Janjowa – 25+ years of experience teaching O Level, IGCSE, A Level Chemistry. Known for turning electrolysis into one of the easiest scoring chapters.

⭐ Student Reviews

“These electrolysis notes are far better than Save My Exams. I finally understood aqueous electrolysis.”
— Ayesha, IGCSE 0620

“Perfect for O Level 5070 Paper 2 & Paper 4. Diagrams + definitions = A*.”
— Hamza, O Level Chemistry

❓ FAQs – Electrolysis Notes

• Are these notes syllabus-aligned?
  Yes, fully aligned with 0620, 5070, 9701, Edexcel & Oxford AQA.
• Is electrolysis important?
  Yes, it appears every year in theory, MCQs & ATP.
• Are PDFs free?
  Yes, free downloads provided.
• Is Faraday’s Law included?
  Yes, for A Level & advanced learners.

🚀 Final Tip for A/A*

Combine these Electrolysis Notes with:

• Chemistry Formula Sheet
• Paper 4 ATP Guide
• Last-Minute Revision Notes