Edexcel A Level Chemistry:复习笔记6.2.9 Catalysis

Properties of Catalysts

 

  • Transition metals are often used as catalysts in the elemental form or as compounds
  • The ability of transition metals to form more than one stable oxidation state means that they can accept and lose electrons easily
  • This enables them to catalyse certain redox reactions. They can be readily oxidised and reduced again, or reduced and then oxidised again, as a consequence of having a number of different oxidation states of similar stability
  • There are two types of catalyst:
    • A heterogeneous catalyst is in a different physical state (phase) from the reactants
      • The reaction occurs at active sites on the surface of the catalyst
      • An example is the use of iron, Fe, in the Haber process for making ammonia

       

N2 (g) + 3H2 (g) ⇌ 2NH3 (g)

  • A homogeneous catalyst is in the same physical state (phase) as the reactants

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