Atom economy % of reactants forming useful products

• A lot of reactions make more than one product

• The atom economy of a reaction tells you how much of the mass of the reactants is wasted when manufacturing a chemical and how much ends up as useful product

• Atom economy = relative formula mass of desired products / relative formula mass of all reactants x 100

• 100% atom economy means that all the atoms in the reactants have been turned into useful products, the higher the atom economy, the greener the process

• Calculating the atom economy

• Identify the desired product

• Work out the Mr of all reactants

• Work out the total M of the desired product

• Use the formula to calculate the atom economy

High atom economy is better for profits and the environment

• Reactions with low atom economy use up resources very quickly

• At the same time, they make lots of waste materials that have to be disposed of

• This makes them unsustainable

• They usually aren’t very profitable

  • Raw materials are expensive to remove and dispose of responsibly

• Reactions with highest atom economy are the ones that only have no product

• The reactions have an atom economy of 100%

  • The more products, the lower the atom economy is likely to be