kinetics

• what must occur for a reaction to take place?


  particles must collide with energy greater than or equal to the activation energy and the right orientation for a successful collision
• what is the symbol and unit for activation energy?


  Ea, KJmol-1
• what is rate of reaction?


  change in concentration of reactants or products per unit of time
• what factors effect rate of reaction?


  • temperature
  • surface area
  • concentration of solutions/ pressure of gases
  • catalysts
• what factor has the greatest effect on rate of reaction?


  temperature
• how does increasing the temperature effect the rate of reaction?


  increase as all particles have more kinetic energy

  many more particles have E≥Ea
• how does surface area effect the rate of reaction?


  greater contact between the reactant particles

  more frequent successful collisions
• how does concentration effect the rate of reaction?


  if concentration increases, rate will increase because there are more particles per unit of volume, so there are more frequent successful collisions.
• how do catalysts effect the rate of reaction?


  the provide an alternative pathway with a lower Ea

  more particles have E≥ Ea
• why don't most collisions result in reactions taking place?


  particles have E<Ea
• what is Maxwell-Boltzmann's distribution?


  the distribution of molecules' energies in a gaseous substance
• what does the total area under the curve represent?


  the total number of molecules in the sample
• why must the area under the Maxwell-Boltzmann's distribution curve stay constant?


  the area represents the total number of molecules in the sample, which remains constant
• what does the peak on Maxwell Boltzmann's distribution curve represent?


  most probable energy
• describe the graph when concentration decreases


  graph profile stays the same but area decreases
• describe the graph when there is a decrease in temperature


  peak shifts to the left, becomes higher and narrower, area stay the same, lower fraction of molecules with E≥ Ea
• describe the graph when there is an increase in temperature


  peak shifts to the right, becomes shorter and wider, area stays the same, higher fraction of molecules with E≥ Ea