Catalysis (OCR A Level Chemistry)

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The Role of a Catalyst

  • A catalyst is a substance that increases the rate of reaction by providing the particles with an alternative mechanism with a lower activation energy
    • Catalysts do not have to be directly involved in the chemical reaction
    • They can provide a surface for the reaction to occur on, e.g. iron in the Haber process
    • Alternatively, they can provide a particle (often an ion) to start the reaction but this particle is regenerated at the end so the catalyst appears unaltered, e.g. chlorine radicals in ozone depletion

Reaction Kinetics Catalyst Reaction Pathway, downloadable AS & A Level Chemistry revision notes

A catalyst increases the rate of a reaction by providing an alternative pathway which has a lower activation energy

Importance of Catalysts

  • Catalysts can be divided into two types:
    • Homogeneous catalysts
    • Heterogeneous catalysts

  • Homogeneous means that the catalyst is in the same phase as the reactants
    • For example, the reactants and the catalysts are all in solution

  • Heterogeneous means that the catalyst is in a different phase to the reactants
    • For example, the reactants are gases, but the catalyst used is a solid

Benefits of catalysts

  • Catalysts speed up the rate of reaction, meaning the use of a catalyst may mean lower temperatures and pressures can be used
    • This can save energy costs as there is reduced energy demand for providing high temperatures and less electrical pumping costs for producing the high pressures usually required
    • This can mean fewer CO2 emissions from burning fossil fuels
  • Catalysts can also enable different reactions to be used, with better atom economy and with reduced waste, or fewer undesired products or less use of hazardous solvents and reactants
  • Catalysts are often enzymes, generating very specific products, and operating effectively close to room temperature and pressure

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Sonny

Author: Sonny

Expertise: Chemistry

Sonny graduated from Imperial College London with a first-class degree in Biomedical Engineering. Turning from engineering to education, he has now been a science tutor working in the UK for several years. Sonny enjoys sharing his passion for science and producing engaging educational materials that help students reach their goals.