Factors that affect the Rate of Reaction

Factors that affect the Rate of Reaction

1. Temperature

   • Increasing the temperature increases the rate of reaction
     • Particles have more energy, so move faster and are more likely to collide
       • Higher collision frequency means a higher rate of reaction

2. Concentration

   • Increasing concentration increases the rate of reaction
     • More reactants in reaction vessel means successful collisions are more likely

3. Pressure

   • Changes in pressure have no effect on reactions that involve solids and liquids
   • Increasing pressure increases the rate of reaction for reactions involving gases
     • Reactant particles are squeezed closer together so collision frequency increases

4. Catalysts

   • Substances that change the rate of reaction but remain chemically unchanged at the end of the reaction
   • Catalysts provide a surface on which the reacting molecules can collide
     • Reduces the amount of energy required for a successful collision
       • Many particles will have more energy than this lower threshold, and so the collision frequency and rate of reaction will increase

5. Surface area

   • Increasing the surface area to volume ratio of the reactants increases the rate of reaction
     • When one of the reactants is in a large lump, the other reactant cannot react with the particles in the middle
       • Smaller particle size leads to higher surface are and an increase in the collision frequency