rate of reactions - chemistry

• how does increasing concentration increase reaction rate?

  • increasing concentration of a substance increases no. reactant particles in given volume

  • this increases frequency of collisions and therefore no. successful collisions in a given time
• how does increasing pressure increase reaction rate?

  • increasing pressure of a substance increases no. reactant particles in given volume

  • this increases frequency of collisions and therefore no. successful collisions in a given time
• how does increasing surface area increase reaction rate?

  • only particles on the surface of a solid can participate in the reaction

  • increasing surface area of a substance increases no. particles on the surface

  • this increases frequency of collisions and therefore no. successful collisions in a given time
• how does increasing temperature increase reaction rate?

  • increasing temperature increases the average kinetic energy of the reactant particles and thus their average speed

  • this increases frequency of collisions and therefore no. successful collisions in a given time

  • however, more importantly, it also increases the proportion of particles w sufficient energy to overcome the Ea, increasing no. successful collisions
• how does adding catalysts increase reaction rate?

  • catalysts provide an alt reaction pathways by lowering Ea of the reaction

  • this increases proportion of particles w sufficient energy to overcome Ea, increasing no. successful collisions
• what are the factors affecting rate?


  SCaT

  • increase surface area → solid, frequency

  • increase concentration → aqueous, frequency

  • increase temperature → all, frequency + proportion

  • add a catalyst → all, proportion

  additional factor: gas pressure → gas, frequency