Atom Economy

• Atom economy - is a measure of the amount os reactant that ends up in a useful product
• Scientists try to choose reaction pathways with high atom economy - so that they can get the largest possible amount of reactant in the desired product
• • In the top reaction , every single atom in the reactants ends up in the product ethanol - so no atoms at all end up as waste products 
  • This means that the top reactions is very efficient 
  • In the second reaction , a waste product is formed : NaBr - this means that some of the atoms that we have put into the reaction are wasted 
  • This means that the bottom reaction is not efficient

  
• Why is atom economy important for economic reasons?

  • Atom economy allows for sustainable development , and allows us to meet the needs of our generation and future ones, as more products are made and less waste is produced 
  • By minimising the production of unwanted products , we save money 
  • We also increase sustainability by not wasting resources (environmental advantage)
• The equation for atom economy is?

  Atom economy = ( relative formula mass of desired products / sum of relative formula masses of all reactants ) x 100
• We cannot have an atom economy greater than 100% , as that would mean you are creating atoms which is not possible
• Calculate the atom economy for the reaction below - the desired product is ethanol to 1dp?

  Atom economy = 51.1%

  
• Calculate the atom economy for the reaction below to 1dp - the desired product is iron chloride

  Atom economy = 66.7%

  
• • Reactions often produce unwanted side-products 
  • These represent a waste of money 
  • So chemists try to find a use for these side-products (e.g. in other reactions) 
  • This ensures that money is not wasted