Electrode Reactions in Electrolysis

This page delves into the specific reactions that occur at the electrodes during electrolysis, which is essential knowledge for GCSE Chemistry electrolysis understanding.

At the cathode (negative electrode), reduction occurs:

• Positive metal ions gain electrons and are reduced to their elemental form.
• The general half-equation is: M²⁺ + 2e⁻ → M

Example: In the electrolysis of lead bromide, lead ions are reduced at the cathode: Pb²⁺ + 2e⁻ → Pb

At the anode (positive electrode), oxidation takes place:

• Negative non-metal ions lose electrons and are oxidized to their elemental form.
• The general half-equation for halide ions is: 2X⁻ → X₂ + 2e⁻

Example: In the same lead bromide electrolysis, bromide ions are oxidized at the anode: 2Br⁻ → Br₂ + 2e⁻

Definition: Reduction is the gain of electrons, while oxidation is the loss of electrons.

Understanding these electrode reactions is crucial for answering GCSE AQA Chemistry electrolysis questions and interpreting electrolysis diagrams in GCSE exams.

Understanding the Basics of Electrolysis

Electrolysis is a fundamental process in GCSE Chemistry that involves using electricity to break down compounds. This page introduces the key concepts of electrolysis and its components.

The term "electrolysis" literally means "splitting up with electricity." When an ionic substance is melted or dissolved, its ions become free to move within the liquid or solution. These liquids, called electrolytes, can conduct electricity. Passing an electric current through electrolytes causes the ions to move towards the electrodes.

During electrolysis, positively charged ions (cations) move to the negative electrode (cathode), while negatively charged particles (anions) move to the positive electrode (anode). At the electrodes, these ions are discharged, producing elements.

Vocabulary: Electrolyte - A substance that conducts electricity when dissolved or molten due to the presence of ions.

Example: In the electrolysis of molten lead bromide, lead ions (Pb²⁺) move to the cathode, while bromide ions (Br⁻) move to the anode.

The setup for electrolysis typically includes:

1. A power source
2. Two electrodes (anode and cathode)
3. An electrolyte (molten or aqueous ionic compound)

Highlight: Electrodes should be made from inert materials to prevent them from reacting with the electrolyte.

This process is crucial in various industrial applications and is a key topic in GCSE AQA Chemistry electrolysis questions.