Metal & Acid Reactions as Redox Reactions (AQA GCSE Chemistry: Combined Science)

Higher Tier Only

• Metal-acid reactions are redox reactions
• Redox means reduction and oxidation at the same time
• If we analyse the ionic equation for the reaction between zinc and hydrochloric acid:

Zn + 2HCl ⟶ ZnCl₂ + H₂

• The ionic equation is:

Zn + 2H⁺⟶ Zn²⁺ + H₂

• This equation can be further split into two half equations illustrating oxidation and reduction individually:

Zn → Zn²⁺ + 2e^–

2H⁺ + 2e^–→ H₂

• The zinc atoms are thus oxidised as they lose electrons.
• The hydrogen ions are thus reduced as they gain electrons.
• Both reactions are occurring at the same time and in the same reaction chamber hence it is a redox reaction