Rates of chemical change

• Measuring volume

  • Gas syringe
  • Upside down measuring cylinder in water
• Rate of reaction

  Measure of how quickly a reactant is used up
• Steeper gradient/line

  Faster rate of reaction
• When line plateaus first


  Reaction is faster
• Pressure


  Reactant particles are more crowded, frequency of successful collisions increases
• Concentration

  Reactant particles are more crowded, frequency of successful collisions increases
• Mean rate of reaction 


  Quantity of reactant used or product formed/Time taken
• Area exposed

  Greater area exposed increases the frequency of successful collisions (e.g powders have a faster rate or reaction than lumps)
• Temperature


  Particles move faster, frequency of successful collisions increases
• Activation energy

  Minimum amount of energy needed for successful collision
• Collision theory

  Reactant particles must collide and have the required activation energy
• Catalyst


  Provides an alternative reaction pathway that has a lower activation energy
• Enzymes

  Biological catalysts
• Temperature 


  Kinetic energy increases

  Particles move faster

  Frequency of successful collisions increases - so does the rate of reaction