redox reactions

• if electrons are transferred, it's a ... reaction

  redox
• redox reaction


  a chemical reaction involving the transfer of one or more electrons from one reactant to another; also called oxidation-reduction reaction, where both oxidation and reduction are taking place
• oxidation


  loss of electrons
• reduction


  gain of electrons
• oil rig

  oxidation is loss, reduction is gain
• all reactions of metals with acids are...

  redox reactions - metal ions lose electrons (oxidation) whilst the acid ions gain electrons (reduction)
• metal and acid redox reaction example

  Fe → Fe2+ + 2e-

  2H+ + 2e- → H2
• halogen displacement reactions are...

  redox reactions - halogens gain electrons (reduction) whilst halide ions lose electrons (oxidation)
• halogen displacement redox reaction example

  Cl2 + 2e- → 2Cl-

  2Br- → Br2 + 2e-
• metal displacement reactions


  a redox reaction where a more reactive metal can displace a less reactive metal from a compound
• metal displacement reactions are...

  redox reactions
• what happens if you put a reactive metal into the solution of a dissolved metal compound?

  the reactive metal will replace the less reactive metal in the compound
• a more reactive metal will...

  displace a less reactive metal from its compound
• metal displacement redox reaction example

  Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s)

  
  

  Fe → Fe2+ + 2e-

  Cu2+ + 2e- → Cu
• in metal displacement reactions the metal ion always...

  gains electrons and is reduced
• in metal displacement reactions the metal atom always...

  loses electrons and is oxidised
• ionic equations show...


  the particles that react and the products they form
• ionic equation example


  Mg(s) + Zn2+(aq) + 2Cl-(aq) → Mg2+(aq)+ 2Cl-(aq) + Zn(s)

  
  

  (because the chlorine ions don't change in the reaction, they're spectator ions - you don't include these in the ionic equation, so to get from this to an ionic equation, you cross out the chloride ions)

  
  

  Mg(s) + Zn2+(aq) → Mg2+(aq) + Zn(s)
• the ionic equation concentrates on...

  the substances which are oxidised or reduced
• half equations


  Equations describing one of either the oxidation or reduction processes of a redox reaction