Atom Economy (DP IB Chemistry)

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

• Efficient processes have high atom economies and are important to sustainable development

  • They use fewer resources

  • Create less waste

• As well as atom economy and percentage yield there are other factors that can be used to gauge the efficiency of a chemical process

  • Rate

  • Quantities of reagents such as catalysts and solvents

  • Energy uses

  • Economic efficiency