Collision Theory

• Reactants must collide with one another before any reaction can occur
• The frequency of collisions would affect how quickly the reactants form the product
• Increasing temperature


  would increase how quickly molecules A and B are moving in the container

  would increase the chances of the two reactants colliding
• If collision is more frequent, product forms more frequently, and the reaction rate is increased
• Increasing size


  increases the likelihood of collision

  the frequency of collision and reaction rate would increase
• Increasing concentration


  would increase the number of particles that could collide and form product

  with more reactants colliding, the reaction rate increases
• Activation energy


  a certain minimum amount of energy

  rebound unchanged

  minimum combined kinetic energy that reactant particles must possess for their collision to result in a reaction
• Collision theory


  for a reaction to occur, particles must collide with a certain minimum energy

  kinetic energies of the colliding particles must add to a minimum value
• Increasing temperature of reactant


  increases the rate of movement (kinetic energy)

  reactants more likely to collide

  collision to be more effective
• Catalyst


  increases reaction rate without being consumed in the reaction

  provides alternate reaction pathways that have lower activation energies than the original

  enzymes are catalysts

  decreases the activation energy

  lower activation energy = sufficient energy to lead to product formation
• If the collision energy exceeds the activation energy barrier, the molecules can undergo chemical transformation and form new products
• Reactant particles must collide with the correct orientation to facilitate bond formation and product formation
• Slight rearrangement of atoms is usually rapid at room temperature
• Ionic reactions occur very fast
• covalent bonds take place more slowly at room temperature.
• Homogeneous reactions occur more rapidly than heterogeneous reactions
• Concentration


  If there is more of a substance in a system, there is a greater chance that molecules will collide and speed up the rate of the reaction
• Catalyst


  lower the energy required to break bonds
• Lower activation energy


  greater proportion of successful collisions between reactant particles.
• Photosynthesis


  green plants that create their own foods

  takes place in the sun

  in the presence of carbon dioxide and water

  chlorophyll stores energy

  turns into glucose
• Climate change


  plants take carbon dioxide from the atmosphere and make it into oxygen

  burning of fossil fuels

  emission of carbon dioxide helps depleting of the ozone

  directs energy back which causes global warming
• Air pollution


  gives off smog (combination of smoke and fog)

  caused by coal and the burning of fossil fuels

  driven by the sunlight

  ozone or O3