catalytic activity

• heterogeneous catalyst

  different phase as the reactants
• strength of adsorption:

  • reactants adsorb on the active site of the catalyst
  • weakens the bonding of reactats
• surface area of the catalyst:

  • increasing surface area to improve efficiency - by using a support medium (minimises cost)
• contact process: heterogenous catalyst

  • V2O5 + SO2 --> V2O4 + SO3
  • V2O4 + 1/2O2 --> V2O5
• haber process: heterogenous catalyst

  • Fe is used as a catalyst
  • N2 + 3H2 --> 2NH3
• catalyst poisoning:

  • impurities bind to the active site of the catalyst
  • reduces surface area and slows the reaction - less product formed
  • replacing the catalyst - increases the cost
• homogeneous catalyst:

  same phase as the reactants
• reaction between iodide and persulfate: homogenous cataylst

  
• autocatalysis:

  product of the reaction can catalyse the reaction
• autocatalytic reaction: homogenous catalyst

  
• why is the uncatalysed reaction of the ethanedioate + manganate ions slow?

  • 2 negative ions repel each other - high activation energy