1.2.5 Atom Economy

• The atom economy of a reaction shows how many of the atoms used in the reaction become the desired product
  • The rest of the atoms or mass is wasted

• It is found directly from the balanced equation by calculating the M_r of the desired product

• In addition reactions, the atom economy will always be 100%, because all of the atoms are used to make the desired product
  • Whenever there is only one product, the atom economy will always be 100%

• For example, in the reaction between ethene and bromine:

CH₂=CH₂ + Br₂ → CH₂BrCH₂Br

• The atom economy could also be calculated using mass, instead or M_r
• In this case, you would divide the mass of the desired product formed by the total mass of all reactants, and then multiply by 100