Cathode Reaction

 Cathode Reaction

Definition

A cathode reaction is the chemical process that occurs at the negative electrode (cathode) during electrolysis, where reduction takes place, meaning positive ions gain electrons.

Explanation

The cathode is connected to the negative terminal of a battery. It attracts cations (positive ions) from the electrolyte. These cations move toward the cathode and gain electrons, becoming neutral atoms or molecules. This gain of electrons is called reduction.

The type of product formed at the cathode depends on the electrolyte, it could be a metal deposited (e.g., copper or silver) or hydrogen gas released (from acids or water).



Key Points

• Happens at the negative electrode (cathode)

• Involves reduction (gain of electrons)

• Cations (positive ions) are attracted to it

• Common products: metals or hydrogen gas

• Electrons flow into the cathode from external circuit

General Reduction Formula

X⁺ + e⁻ → X

Example:

Cu²⁺ + 2e⁻ → Cu (Copper deposited)

2H⁺ + 2e⁻ → H₂ (Hydrogen gas formed)

Examples

• Electroplating silver: Ag⁺ + e⁻ → Ag

• Refining copper: Cu²⁺ + 2e⁻ → Cu

• Water electrolysis: 2H⁺ + 2e⁻ → H₂

Applications / Relevance

• 💍 Electroplating metals (silver, gold, etc.)

• ⚙️ Metal extraction and refining

• 🧪 Hydrogen gas production in labs

• 🔋 Battery discharge (cathode gains electrons)

Question

What always happens at the cathode during electrolysis?

Answer:

Reduction — positive ions gain electrons and become neutral substances.