(46) GCSE Chemistry - Electrolysis Part 1 - Basics and Molten Compounds #40

Electrolysis Overview

• Definition: Electrolysis is the process of using electricity to split up substances, particularly to separate elements in ionic compounds.

• Main focus: Using electrolysis to separate elements from insoluble ionic compounds, specifically lead bromide.

Equipment Required

Beaker

• Holds the electrolyte (the liquid or solution containing the ionic compound).

• Importance of free-moving ions in the electrolyte for effective electrolysis.

Electrolyte

• For soluble compounds (e.g., copper sulfate), dissolve them in water to create an aqueous electrolyte.

• For insoluble compounds (e.g., lead bromide), melt them to obtain a molten liquid where ions can move freely.

• Example: Molten lead bromide contains free-moving lead ions (Pb²⁺) and bromide ions (Br⁻).

Electrodes

• Made of solid conductive materials, typically metal or carbon.

• Types of Electrodes:

  • Anode (Positive Electrode): Attracts negative ions (anions).

  • Cathode (Negative Electrode): Attracts positive ions (cations).

Connecting Equipment

• Connect electrodes with wire to enable electron flow.

• Use a power supply, like a battery, to drive the flow of electrons through the circuit.

Process of Electrolysis

• Function: Pass an electric current through the electrolyte (molten lead bromide) to separate lead and bromine.

• Ion Movement:

  • Negative bromide ions (Br⁻) move towards the anode and get discharged to form bromine gas (Br₂).

  • Positive lead ions (Pb²⁺) move towards the cathode and get discharged to form pure lead (Pb).

Chemical Reactions in Electrolysis

Anode Reaction

• Oxidation: Bromide ions (Br⁻) lose electrons and convert to bromine (Br₂).

  • Half-equation: Br⁻ → Br₂ + e⁻

Cathode Reaction

• Reduction: Lead ions (Pb²⁺) gain electrons and convert to pure lead (Pb).

  • Half-equation: Pb²⁺ + 2e⁻ → Pb

Overall Process Description

• Electrons are transferred from bromide ions at the anode to lead ions at the cathode.

• The process effectively uses electricity to convert ionic species in compounds back into their pure elemental forms.

Future Learning Topics

• Upcoming videos will cover:

  • Electrolysis of metal oxides for pure metal extraction.

  • Electrolysis of aqueous solutions.