Kinetics

• collision theory = for a reaction to occur, 2 conditions must be fulfilled

  • particles collide with minimum activation energy
  • particles collide with the correct orientation
  • not enough energy/not correct orientation -> unsuccessful collision
  • activation energy = minimum amount of energy particles require for a collision to result in a reaction

  A) activation energy

  B) overall energy change

  C) activation energy

  D) overall energy change

  E) transition state/activated complex

  F) transition state/activated complex

  G) transition state= bonds in process of being made/broken

  
• rate of reaction = the change in concentration/volume of a substance per unit of time

  • factors affecting RofR: pressure, concentration, surface area, temperature, catalyst
  • increase conc/pressure -> increase no. of particles per given volume -> more collisions -> more successful collisions
  • increase SA -> increases surface of reactant exposed -> more collisions per given time -> more successful collisions
  • increase temp -> increase KE of particles -> more movement -> more collisions -> more successful collisions
  • adding a catalyst -> lowers Ea -> more particles have enough energy to react
• Maxwell-Botlzmann distribution curve

  • can see how much energy a particle has by how fast it moves
  • can plot no. of particles against energy
  • area under curve = measure of the total no. of particles present

  A) Emp = most probable energy

  B) average energy

  C) activation energy

  D) particles with enough energy to react

  
• Maxwell-Botlzmann distribution - temperature increase

  • increase temp -> increased proportion of reactant with minimum Ea -> increased frequency of collisions as particles move faster therefore more successful collisions

  A) lower temp

  B) higher temp

  
• Maxwell-Botlzmann distribution - catalysts

  • catalyst = substance that speeds up the rate of reaction without getting used up
  • provides alternative reaction pathway that lowers activation energy
  • lowers Ea -> increased proportion of particles with minimum Ea -> more successful collisions
  • in catalytic converter: metal catalyst weakly holds gases in right position to react (adsorption) & products break away from metal (desorption)