oxidation reactions

• What are redox reactions important for?

  Many areas of life, e.g. breathalysers
• What do redox reactions involve?

  Loss and gain of electrons
• What does OIL RIG stand for?

  Oxidation Is Loss, Reduction Is Gain
• What does an oxidising agent do?

  It oxidises another compound
• What happens to an oxidising agent during a reaction?

  It gains electrons and is reduced
• What does a reducing agent do?

  It reduces another compound
• What happens to a reducing agent during a reaction?

  It loses electrons and is oxidised
• In the reaction A + B → A+ + B−, what is B?

  B is an oxidising agent
• In the reaction A + B → A+ + B−, what happens to A?

  A is oxidised by losing electrons
• What does an ionic half-equation show?

  Either reduction or oxidation
• What is an example of an ionic half-equation for reduction?

  O2 + 4e- → 2O2-
• How do you generate a full balanced equation from ionic half-equations?

  Add both half-equations and balance electrons
• What is the ionic half-equation for the oxidation of Ti?

  Ti → Ti4+ + 4e-
• What is the ionic half-equation for the reduction of Cl2?

  Cl2 + 2e- → 2Cl-
• What is the full balanced equation from the half-equations for Ti and Cl2?

  Ti + 2Cl2 → Ti4+ + 4Cl-
• What is disproportionation in redox reactions?

  When an element is both oxidised and reduced
• What happens to copper (I) ions in disproportionation?

  Forms solid copper and copper (II) ions
• What is the reaction for the disproportionation of copper (I)?


  2Cu+(aq) → Cu(s) + Cu2+(aq)
• What is the disproportionation reaction of copper (I) oxide with dilute sulphuric acid?

  Cu2O(s) + H2SO4 → Cu(s) + CuSO4 + H2O
• What oxidation states does copper change to in the disproportionation reaction?

  From +1 to 0 and +2
• What are the key concepts of redox reactions?

  • Involves loss and gain of electrons
  • Oxidising agents gain electrons and are reduced
  • Reducing agents lose electrons and are oxidised
  • Disproportionation involves an element being both oxidised and reduced
• What are the steps to write ionic half-equations?

  1. Identify oxidation or reduction
  2. Write the half-equation for the process
  3. Balance the number of electrons
  4. Combine half-equations for full reaction
• What is the equation for a halogen reaction with a cold alkali?


  X₂ + 2NaOH → NaX + NaOX + H₂O
• What is the ionic equation for a halogen reaction with a cold alkali?


  X₂ + 2OH⁻ → X⁻ + OX⁻ + H₂O
• What is the equation for a halogen reaction with a hot alkali?


  X₂ + 6NaOH → 5NaX + NaXO₃ + 3H₂O
• What is the ionic equation for a halogen reaction with a hot alkali?


  3X₂ + 6OH⁻ → 5X⁻ + XO₃⁻ + 3H₂O