Introduction
Electrolysis is a chemical process that uses electrical energy to cause a non-spontaneous redox reaction. It is widely used in industries such as metal purification, electroplating, and extraction of metals. Electrolysis plays a central role in electrochemistry and is highly examined in NECTA practical and theory papers.

Key Concepts

🔹 1. Definition of Electrolysis

Electrolysis is the process of using electricity to break down an electrolyte into its constituent elements or ions by forcing a redox reaction.

🔹 2. Electrolyte

A substance that conducts electricity when molten or dissolved in water and undergoes decomposition during electrolysis.

Types of electrolytes:

• Strong electrolytes – completely ionize (e.g. HCl, NaOH)

• Weak electrolytes – partially ionize (e.g. CH₃COOH)

• Molten salts – e.g. molten NaCl

• Aqueous ionic compounds – e.g. CuSO₄(aq)

🔹 3. Electrochemical Cell Setup

An electrolysis system includes:

• Electrolyte solution

• Electrodes connected to a DC power source

🔁 Mnemonic: “PANIC” = Positive Anode, Negative Is Cathode

🔹 4. Nature of Electrodes

• Inert electrodes (e.g. platinum, graphite): do not take part in reaction

• Active electrodes (e.g. copper in CuSO₄): participate in reaction

🔹 5. General Reactions at Electrodes

🔹 6. Distinction Between Electrolysis and Galvanic Cell

🔹 7. Common Electrolysis Setups in NECTA

1. Electrolysis of Copper(II) Sulfate solution

   • Inert electrodes: Cu deposited at cathode

   • Active Cu electrodes: copper dissolves from anode

2. Electrolysis of Molten NaCl

   • Produces sodium metal and chlorine gas

3. Electrolysis of Dilute Sulfuric Acid (H₂SO₄)

   • Produces hydrogen gas at cathode and oxygen gas at anode

🧠 NECTA-Style Question:

Question:
Describe the electrode reactions during electrolysis of copper(II) sulfate using:

• (a) Inert electrodes

• (b) Copper electrodes

Answer:

(a) Inert Electrodes (graphite):

• Cathode: Cu²⁺ + 2e⁻ → Cu (reduction)

• Anode: 2H₂O → O₂ + 4H⁺ + 4e⁻ (oxidation)

(b) Copper Electrodes:

• Cathode: Cu²⁺ + 2e⁻ → Cu (deposition)

• Anode: Cu → Cu²⁺ + 2e⁻ (dissolves)

🧪 Real-Life Applications:

• Electroplating (jewelry, utensils)

• Metal refining (e.g. copper purification)

• Electrolysis of brine to produce chlorine

• Hydrogen fuel production

✅ Summary

• Electrolysis uses electricity to drive redox reactions

• Reduction occurs at cathode, oxidation at anode

• The choice of electrode (inert or active) affects the reactions

• Key in industrial, laboratory, and NECTA contexts