Electrolysis | Chemistry for Grade 11 (IGCSE) PDF Download

Electrolysis: General Principles

• When an electric current flows through a molten ionic compound, or through its aqueous solution, the compound undergoes decomposition.
• This decomposition process also applies to aqueous solutions of ionic compounds.
• Unlike covalent compounds, which cannot conduct electricity, ionic compounds do not undergo electrolysis.
• Ionic compounds in their solid state also cannot conduct electricity because they lack free ions capable of movement to carry the electrical charge.

Key Terms in a Simple Electrolytic Cell

• Electrode: A metal or graphite rod enabling electric current flow in or out of an electrolyte.
• Electrolyte: An ionic compound in molten or dissolved form that conducts electricity.
• Anode: The positive electrode in an electrolysis cell.
• Anion: A negatively charged ion attracted to the anode.
• Cathode: The negative electrode in an electrolysis cell.
• Cation: A positively charged ion drawn towards the cathode.
• The Basic Setup of an Electrolytic Cell
• Metals and hydrogen ions become positively charged ions, leading to the formation of either a metal or hydrogen gas at the cathode.
• Non-metals, except hydrogen, produce negatively charged ions, resulting in the formation of non-metallic substances at the anode.

Electrolysis: Charge Transfer

• When conducting electrolysis, an electric current must circulate around the circuit.
• For this process to take place, charge transfer occurs throughout the circuit by charge carriers.
• The power source supplies the cathode with electrons, leading it to acquire a negative charge.
• Positive ions, known as cations, within the electrolyte migrate towards the cathode where they acquire electrons.
• Negative ions, or anions, within the electrolyte move towards the anode where they release electrons.
• Electrons travel from the anode back to the power source.
• Within a complete circuit, electrons function as the charge carriers in the external circuit, while ions serve as the charge carriers in the electrolyte.