kinetics

• Activation Energy (Ea)

  The minimum amount of energy needed for the particles to react

  
• Collision Theory

  • Particles must Collide
  • The energy of the collision must be greater than the Activation Energy (E ≥ Ea)
  • Particles must collide with the correct orientation
• Energy Profile Diagram for an Exothermic reaction

  Show the activation energy

  
• How activation energy is measured

  Activation energy is measured from Reactants to the top of the hump
• How ∆H is measured

  • ∆H is the difference between the enthalpy of the reactants and products
  • ∆H is negative (exo)
• Energy Profile Diagram for an Endothermic reaction


  Show the activation energy

  
• How ∆H is measured

  • ∆H is the difference between the enthalpy of the reactants and products
  • ∆H is positive (endo)
• For a reaction to happen there must be s= SUCCESSFUL COLLISIONS have E≥ Ea
• Factors that increase the number of successful collisions and hence the rate of reaction

  • Increase in concentration of reactants
  • Increase in pressure of gaseous reactants
  • Increase in surface area of solid reactants
  • Increase in temperature
  • Adding a catalyst
• What happens to the Rate of reaction when the concentration of a reactant is increased

  1. The particles are closer together

  2. the particles collide more frequently

  3. more frequent successful collisions

  4. faster rate of reaction
• What happens to the Rate of reaction when the pressure of a reactant is increased

  1. The particles are closer together

  2. the particles collide more frequently

  3. more frequent successful collisions

  4. faster rate of reaction
• What happens to the Rate of reaction when the surface area of a reactant is increased

  1. greater surface is exposed for collisions

  2. The particles collide more frequently

  3. There are more successful collisions

  4. And therefore, a faster rate of reaction
• Marking guidance when drawing a Maxwell Boltzmann distribution

  • The line must start at the origin -THERE ARE NO PARTICLES WITH ZERO ENERGY
  • The distribution is NOT SYMMETRICAL
  • The area UNDER the curves represents the TOTAL NUMBER OF PARTICLES
  • The line at higher energy MUST NOT TOUCH the x-axis (it becomes parallel)