Topic 4 - Extracting metals and equilibria

• Reactivity series of metals

  Orders metals from the most reactive to the least reactive
• Metals in reactivity series

  • Potassium
  • Sodium
  • Lithium
  • Calcium
  • Iron
  • Silver
  • Gold
• Oxidation


  Loss of electrons
• Reduction


  gain of electrons
• Metals above hydrogen in reactivity series

  React with dilute acids
• Top 4 metals in reactivity series

  React with cold water
• Reaction of metal with water

  Metal hydroxide + hydrogen
• Displacement reaction


  Reaction where a more reactive metal replaces a less reactive metal in a compound
• Displacement reactions are redox reactions
• Extraction methods for metals

  • Electrolysis for metals above carbon
  • Carbon reduction for metals above silver
  • Natural state for silver and gold
• Extraction of iron using carbon

  Iron oxide + carbon -> carbon dioxide + iron
• Low grade ores


  Ores with a lot of rock and not much metal
• Methods for extracting metals from low grade ores

  • Bio leaching using bacteria
  • Phytoextraction using plants
• Reversible reaction


  Reaction that can go forwards and backwards
• Dynamic equilibrium


  Forward and backward reactions happening at the same rate
• Dynamic equilibrium can only occur in a closed system
• Position of equilibrium


  The side of the reaction with more material
• Factors that affect position of equilibrium

  • Temperature
  • Pressure
  • Concentration
• Exothermic reaction


  Reaction that releases heat
• Endothermic reaction


  Reaction that absorbs heat
• Haber process


  • Combines nitrogen and hydrogen to produce ammonia
  • Forward reaction is exothermic
  • Uses iron as a catalyst
• To maximise ammonia production in Haber process, use high temperature (450 degrees c) and high pressure ( 200 atmospheres)
• If concentration of products increases :

  • Equilibria shifts left so more reactants are produced
• Is concentration of reactants increases:

  • Equilibrium shifts right so more products are produced
• An increase in pressure will favour the side with the least amount of moles
• If reaction produces an increased pressure

  • The larger volume of gas decreases yield equilibrium
  • The smaller volume of gas increases yield equilibrium
• If reaction produces a decreased pressure :

  • The larger volume of gas increases yield equilibrium
  • The smaller volume if gas decreases yield equilibrium
• If temperature increases

  • Equilibrium moves in direction of endothermic reaction
• Is temperature decreases

  • Equilibrium moves in direction of exothermic reaction