6.1 - Rate of reaction

• To increase rate of reaction:

  • Lower volume
  • Increase number of particles (concentration)
  • Increase temperature
  • Increase surface area
  • Use a catalyst to lower activation energy
• Rate of reaction is the speed at which a reaction can occur, this depends on:

  • The frequency of collisions
  • The energy of collisions
• Increasing the concentration or pressure of a solution increases the frequency of collisions, therefore increasing the rate of reaction.

  This is because:

  • The more particles there are in a substance, the more likely they are to collide with each other
  • The higher the pressure, the less space for the particles to move around and more likely they are to collide with each other.
• The rate of a chemical reaction can be found by measuring the quantity of a reactant used or the quantity of product formed over time.
• There are two formulae to calculate the mean rate of reaction:

  • Mean rate of reaction = quantity of reactant used / time taken
  • Mean rate of reaction = quantity of product formed / time taken
• 4 Possible signs a chemical reaction has taken place include:

  • Change in mass
  • Change in temperature
  • Colour change
  • Fizzing
• The equipment required to measure:

  • Volume of gas produced = Gas syringe
  • Temperature change = Thermometer
  • Change in mass = Top pan balance
  • Time = Stopwatch
• Catalysts lower the activation energy of a reaction
• Activation energy is the energy required for a reaction to occur
• Collision theory is the theory describing that chemical reactions can occur only when reacting particles collide with each other and with sufficient energy
• Catalytic activity is the rise in chemical reaction rate caused by the presence of a catalyst.