1.5 Kinetics

• How does a reaction occur?

  When particles collide
• What is rate of reaction?

  The change of concentration/amount of a reactant or product per unit time
• What is collision theory?

  Fo a reaction occur particles must:

  -collide in the right direction

  -have a minimum amount of kinetic energy
• What is activation energy?

  Minimum amount of energy required for a reaction to occur
• What does a Maxwell-Boltzmann distribution show?

  Energy in gas particles
• Why does the graph start at 0?

  No particles have zero kinetic energy
• What is the area under the curve equal to?

  total number of molecules
• How does increasing temperature affect rate?

  Increase temperature = more particles with energy greater than activation energy
• How does an increase in temperature affect the graph?

  1. Curve shifts to right

  2. Peak is lower

  3. Area under curve is the same

  4. Area under curve beyond activation energy increases
• How does a decrease in temperature affect the graph?

  Decrease temperature = less particles with energy greater than activation energy
• How does a decrease in temperature affect the graph?

  1. Curve shifts to left

  2. Peak is higher

  3. Area under curve is the same

  4. Area under curve beyond activation energy decreases
• Why do we get a faster rate of reaction when temperature is increased?

  -Particles move around more at higher temperatures therefore they collide mor often

  -the combination of more collisions and more energetic collisions means that small increases in temperature leads to a larger increase in rate
• How does pressure affect rate?

  Increase in pressure = particles are closer together and collide more often therefore more frequency collisions and a higher chance of a reaction
• How does concentration affect rate?

  Increasing concentration = increase rate of reaction as particles are closer together and collide more often therefore there is a greater chance of a reaction
• What is a catalyst?


  A substance that increases the rate of a reaction by providing an alternative pathway that has a lower activation energy. The catalyst is chemically unchanged at the end of the reaction
• How does a catalyst affect the graph?

  Activation energy will shift to left therefore a greater area of particles with energy greater than activation energy
• How can you measure rate of reaction by timing how long it takes for a precipitate to form?

  1. Place a cross on a paper and time how long it takes for the cross to disappear
• How can you measure rate of reaction by the amount of mass lost?

  For reactions that produce a gas - place reaction on balance and measure the mass loss as gas is lost
• How can you measure rate of reaction by the volume of gas produced?

  Measure the amount of gas produced using a gas syringe