Rates of Reaction

• Rate of a chemical reaction


  How fast the reactants are changed into products
• Reactions


  • Rusting (slow)
  • Burning (fast)
• Graphs showing rate of reaction


  • Steeper line = faster rate
  • Line becomes less steep as reactants are used up
  • Flat line = reaction has finished
• Reactions are fastest at the start


  The line is steepest here
• Over time the line becomes less steep


  As the reactants are used up
• Faster reactions


  • Steeper lines to begin with
  • Become flat more quickly
• Reaction conditions


  • Line 1: Original reaction
  • Line 2: Faster reaction
  • Line 3: Slower reaction
  • Line 4: More product formed
• Lines 1, 2 and 3 all meet at the same level

  They all produce the same amount of product, just take different times
• Collision theory


  Particles must collide with enough energy in order to react
• Activation energy


  Minimum (smallest) amount of energy particles need to collide with
• More often the particles collide

  Faster the reaction will happen
• More energy the particles have

  Faster the reaction will be
• This is because there's more chance that they'll have at least the activation energy