OCR - A-Level - Chemistry - Collision Theory and Rates of Reaction

OCR - A-Level - Chemistry - Collision Theory and Rates of Reaction

1. Rate = Change in concentration/time

   • mol/dm^3/s

2. Initial rate - concentration of reactants are highest at the start of a reaction when the rate is at its fastest

   • Rate slows as reactant concentration decreases (as it gets used up)
     • When any reactant has a concentration of zero, the reaction stops

3. Factors affecting the rate of a chemical reaction

   • Temperature
     • Temp increases, rate increases
   • Pressure (gas)
     • Pressure increases, rate increases
   • Concentration
     • Conc increases, rate increases
   • Surface area
     • SA increases, rate increases
   • Catalysts
     • Rate increases in presence
   • Must be sufficient energy to overcome activation energy
   • Correct orientation of reactants for collisions

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