Oxidation and reduction

• From what type of ores are many metals extracted?

  Metal oxide ores
• What must be removed from metal oxide ores to obtain the metal?

  The oxygen must be removed
• What is the term used when oxygen is removed from a compound?

  The compound is said to be reduced
• What is the definition of oxidation?

  Oxidation is the gain of oxygen by a substance
• What is the definition of reduction?

  Reduction is the loss of oxygen from a substance
• What occurs when one substance is oxidised?

  Another substance will be reduced
• What are reactions in which oxidation and reduction occur called?

  Redox reactions
• How is iron obtained from iron oxide?

  By removing the oxygen from iron oxide by heating with carbon
• What happens to carbon during the reduction of iron oxide?

  Carbon is oxidised to carbon dioxide
• Write the chemical equation for the reduction of iron oxide by carbon.

  Iron oxide + carbon → iron + carbon dioxide
• How is aluminium obtained from aluminium oxide?

  By removing oxygen from aluminium oxide by electrolysis
• What is the process of obtaining metals from their ores called?

  Reduction of their ores
• What happens during corrosion of a metal?

  A metal reacts with oxygen, making it weaker over time
• What is rusting?

  The corrosion of iron that requires water as well as oxygen
• How does the reactivity of a metal affect its corrosion rate?

  The more reactive a metal is, the more rapidly it corrodes
• Why does gold not corrode?

  Because it does not react with oxygen
• What is the significance of the Grouville Hoard found in Jersey?

  It contains about 70,000 coins and pieces of gold jewellery that are 2000 years old and have not corroded
• Why do some reactive metals like aluminium not corrode quickly?

  Because their surfaces form a protective oxide layer
• What has happened to the iron in the Angel of the North?

  It has reacted with oxygen and water
• What does the rusting of iron indicate about its reaction with oxygen?

  Iron gains oxygen and is oxidised
• What does the red color of Mars indicate about its iron content?

  It indicates that the iron has rusted over billions of years
• What do the dark areas on the Moon's surface tell us about its iron-rich rocks?

  The iron in these rocks has not rusted
• What can the different colors in the iron-rich rocks on Mars and the Moon tell us about their atmospheres?

  They indicate the presence or absence of oxygen in their atmospheres
• What is oxidised in the process of reducing iron oxide with carbon?

  Carbon is oxidised to carbon dioxide
• What is the reaction of copper oxide with hydrogen?

  CuO + H₂ → Cu + H₂O
• Which substance is oxidised in the reaction of copper oxide with hydrogen?

  Copper oxide is oxidised
• Which substance is reduced in the reaction of copper oxide with hydrogen?

  Hydrogen is reduced
• How would you rank metals A, B, and C based on their corrosion rates?

  Metal A is the least reactive, followed by metal C, then metal B as the most reactive
• What does the half-equation Mg²⁺ + 2e⁻ → Mg represent?

  The reduction of magnesium ions to magnesium metal
• At which electrode does the reaction Mg²⁺ + 2e⁻ → Mg occur?

  At the cathode
• Is the reaction Mg²⁺ + 2e⁻ → Mg oxidation, reduction, or neither?

  It is a reduction reaction
• What are the key concepts of oxidation and reduction?

  • Oxidation: gain of oxygen, loss of electrons
  • Reduction: loss of oxygen, gain of electrons
  • They always occur together in redox reactions
• What are the processes involved in the extraction of metals from their ores?

  1. Removal of oxygen from metal oxide ores
  2. Reduction of the metal oxide to obtain the metal
  3. Oxidation of the reducing agent (e.g., carbon)
• What factors influence the corrosion of metals?

  • Reactivity of the metal
  • Presence of oxygen and water
  • Formation of protective oxide layers
• What are the implications of the findings from the Grouville Hoard?

  • Gold does not corrode, preserving ancient artifacts
  • Provides insight into historical metalworking and trade