Catalyst

• A catalyst is a substance (usually a transition metal) which speeds up a chemical reaction, but remains unchanged at the end
• Adding a catalyst increases the rate of reaction
• A catalyst allows the reaction to go by an alternative pathway with lower activation energy
• More particles will have an energy greater than or equal to the activation energy, therefore successful collision rate increases resulting in increased rate of reaction
• For gaseous reactants, if catalyst is solid metal, the catalyst provides a surface for reaction to take place on
• The larger the surface area of the metal catalyst, the larger the area for reaction to take place therefore the higher rate of reaction

  
• Enzymes are biological catalysts which speed up reactions but remain chemically unchanged at the end
• Enzymes function best at optimum temperature and pH level otherwise they may denature and completely stop functioning