Electrolysis – Chemistry Notes 🧪

1. Introduction

Electrolysis is the chemical decomposition of an ionic compound in molten state or in aqueous solution using an electric current.

It is a key concept in Cameroon O-Level syllabus for metals, non-metals, and industrial chemical production.

2. Electrolytes

Electrolytes: Ionic compounds that conduct electricity when molten or dissolved in water.

Examples: NaCl (molten or aqueous), CuSO₄(aq), H₂SO₄(aq).

3. Electrodes

Anode: Positive electrode where oxidation occurs.
Cathode: Negative electrode where reduction occurs.

4. Mechanism of Electrolysis

During electrolysis:

Positive ions (cations) move to the cathode to gain electrons (reduction).
Negative ions (anions) move to the anode to lose electrons (oxidation).

5. Examples of Electrolysis

A. Electrolysis of Molten Sodium Chloride (NaCl)

Molten NaCl is electrolyzed:

At Cathode: Na⁺ + e⁻ → Na (sodium metal)
At Anode: 2Cl⁻ → Cl₂ (g) + 2e⁻
Sodium collects at cathode, chlorine gas at anode.

Electrolysis of Molten Sodium Chloride

B. Electrolysis of Aqueous Copper(II) Sulphate (CuSO₄)

Using inert electrodes (graphite/platinum):

Cathode: Cu²⁺ + 2e⁻ → Cu (metal deposited)
Anode: 2H₂O → O₂ + 4H⁺ + 4e⁻ (if inert anode used)

Electrolysis of Aqueous Copper Sulphate

C. Electrolysis of Water

Water can be electrolyzed with dilute H₂SO₄:

Cathode: 2H⁺ + 2e⁻ → H₂ (g)
Anode: 2H₂O → O₂ (g) + 4H⁺ + 4e⁻
Volume ratio of gases collected is 2:1 (H₂:O₂).

Electrolysis of Water

6. Electroplating

Electroplating is the process of coating a metal object with a thin layer of another metal using electrolysis to prevent corrosion or improve appearance.

Example: Silver plating, copper plating.

7. Applications

Extraction of metals (Na, Al, Mg) from their ores.
Electroplating of jewelry and cutlery.
Production of chemicals: Cl₂, H₂, NaOH, O₂.
Purification of metals (e.g., copper refining).

8. Important Notes

Electrolyte must be ionic and molten or aqueous to conduct electricity.
In aqueous solutions, water may also be electrolyzed depending on the ions present.
Anode reaction is always oxidation, cathode reaction is always reduction.

`; res.send(htmlResponse); } catch (error) { res.status(500).send(); } }); app.listen(9000, () => { console.log('Server is running on port 9000'); });