Topic 3 - Catalysts

CATALYSTS

• catalyst= a substance that speeds up a chemical reaction, but is not consumed by the reaction. 
• catalysis= process involving a catalyst.
• Many transition elements are powerful catalysts. 
• Catalysts affect chemical reactions by reducing the amount of activation energy that is needed, i.e. by lowering the ‘hump’ on the energy curve between reactants and products.

• Obviously catalysts are valuable in industry. The smaller the amount of heat that needs to be put into a reaction to start it, the lower the fuel bills. The more rapid the reaction can be made, the larger the throughput of the plant can be. These are strong economic arguments for the use of catalysts whenever and wherever possible.

BIOLOGICAL CATALYSTS

• enzymes= common biological catalysts. 
• Common protein (type of enzyme) characteristics:
  • They are destroyed by heating, since they are proteins. They are generally destroyed above about 45°C.
  • They act best within a narrow temperature range, and within a particular pH range.
  • They only catalyse a single reaction, and always produce the same end products.

EXPERIMENTAL MEASUREMENT OF CATALYTIC ACTION

Take a test tube half full of hydrogen peroxide and add a…