Yield and Atom Economy

• What is the formula for percentage yield?

  Percentage yield = (Amount of product produced / Maximum amount of product possible) x 100
• Why might it not be possible to obtain the calculated amount of a product?

  Because the reaction may not go to completion, product may be lost, or reactants may react differently.
• What are the three reasons why the calculated amount of a product may not be obtained?

  • Reaction may not go to completion because it is reversible.
  • Some product may be lost when separated from the reaction mixture.
  • Some reactants may react in ways different from the expected reaction.
• What does 'yield' refer to in a chemical reaction?

  Yield refers to the amount of product obtained.
• How do you calculate the theoretical mass of a product from a given mass of reactant?

  1. Calculate moles of reactant: mol = mass / molar mass.
  2. Use balancing numbers to find moles of product.
  3. Calculate theoretical mass: mass = mol x molar mass.
• What is atom economy?

  Atom economy measures the amount of starting materials that end up as useful products.
• Why is atom economy important?

  It is important for sustainable development and economic reasons.
• What is the formula for calculating atom economy?

  Atom economy = (Mr of desired product from reaction / Sum of Mr of all reactants) x 100
• What factors might influence the choice of a particular reaction pathway?

  • Atom economy
  • Yield
  • Rate
  • Equilibrium position
  • Usefulness of by-products