Redox Reactions | Chemistry for Grade 11 (IGCSE) PDF Download

Oxidation & Reduction

Redox reactions

• Oxidation and reduction occur simultaneously within a single reaction, termed as redox reactions.
• Oxidation involves the addition of oxygen to an element or compound.
• Conversely, reduction entails the removal of oxygen from an element or compound.

Example: Identifying the loss and gain of oxygen in an equation

zinc oxide + carbon → zinc + carbon monoxide
ZnO + C → Zn + CO

• In this chemical reaction, zinc oxide undergoes reduction as it loses oxygen.
• Conversely, the carbon atom experiences oxidation as it gains oxygen.

Names using oxidation numbers

• Transition elements have the ability to form ions with varying charges, leading to different bonding patterns.
• In nomenclature, the charge on the ion is indicated using a Roman numeral following the element's name.
• For instance, iron can generate ions with a 2+ charge, labeled as iron(II) ions, or a 3+ charge, known as iron(III) ions, with the Roman numeral representing the oxidation number.
• When iron reacts with oxygen to create iron oxide, the resulting formula relies on the oxidation state of the iron ions.
• The compound featuring iron with a 2+ charge is represented by the formula FeO and termed iron(II) oxide.
• Conversely, the compound where iron has a 3+ charge adopts the formula Fe₂O₃ and is referred to as iron(III) oxide.