Topic 9 - Kinetics I

• Rate of reaction is found by drawing a tangent and calculating the gradient
• Collision theory is the idea that reactions happen by molecules colliding
• Collisions can be affected by:

  • Orientation
  • Activation energy
  • Steric hindrance
• An increase in concentration increase rate of reaction as there are more molecules to be able to collide, leading to more frequent successful collisions
• An increase in pressure increases rate of reaction because there are more particles per volume making them physically closer together and more likely to collide
• A larger surface area increases rate of reaction as there is more room for particles to collide
• Temperature increases rate of reaction because:

  • Particles are moving faster so are more likely to collide
  • More particles have activation energy
• Catalysts increase rate of reaction by finding a pathway with a lower activation energy
• When temperature is increased the maxwell-boltzmann curve flattens and lengthens
• The maxwell-boltzmann curve has fraction of molecules with the energy on the y axis and energy on the x axis
• Heterogenous catalysts are catalysts that are in a different state than the reaction
• Industry mostly uses heterogenous catalysts
• Catalysts are useful in industry as they increase yield per time and lower energy costs
• The minimum amount of energy needed for collisions to be successful is called activation energy
• When temperature is increased, the maxwell-boltzman curve lowers and shifts to the right while the area under the curve remains constant
• When concentration is increased there are more particles per unit of volume so more frequent successful collisions
• Increasing the concentration will not change the shape of the maxwell-boltzman curve, but the area under the curve will increase
• When temperature is increased, more particles have the activation energy and particles will be moving more, so there will be more frequent, successful collisions
• Increasing surface area increases rate of reactions because collisions will be more frequent
• A catalyst increases the rate of reaction by finding an alternate reaction pathway with a lower activation energy without being used up
• If activation energy is lower, more particles will have the activation energy