Kinetics

• Rate of reaction

  The change in concentration or the amount of a reactant or product per unit time
• For a reaction to occur, particles must collide in the right direction and have a certain minimum kinetic energy
• Activation energy


  The minimum amount of energy required for a reaction to occur
• Activation energy


  • It is the difference between the reactants and the top of the reaction profile line
  • Reactions with low activation energy need less energy to break them
• Maxwell-Boltzmann distribution


  Shows the energy in gas particles, with some moving slowly and some quickly
• The area under the Maxwell-Boltzmann curve is equal to the total number of molecules
• Mode


  The most likely energy of a particle in a sample
• Mean


  The average energy of the particles
• Particles with energy greater than the activation energy are the ones that can react and produce products
• Increasing temperature


  Increases the proportion of particles with energy greater than the activation energy
• Decreasing temperature


  Decreases the proportion of particles with energy greater than the activation energy
• Effect of temperature on rate

  • Higher temperatures lead to more frequent and more energetic collisions, resulting in a large increase in reaction rate
• Effect of concentration/pressure on rate

  • Higher concentration/pressure leads to more frequent collisions, increasing the reaction rate
• Catalyst


  A substance that increases the rate of a reaction by providing an alternative pathway with lower activation energy
• Adding a catalyst


  Lowers the activation energy of the reaction
• Catalysts remain chemically unchanged at the end of the reaction
• Measuring reaction rate


  1. Timing the formation of a precipitate

  2. Measuring mass loss due to gas production

  3. Measuring volume of gas produced over time