Calculating Percentage Yield (T)

• What is the maximum theoretical yield of magnesium sulfate from 48 grams of magnesium?

  240 grams
• Why might the percentage yield of a reaction be less than 100%?

  Because of product loss, unexpected reactions, and incomplete reversible reactions
• What is the formula for calculating percentage yield in a chemical reaction?

  • Percentage yield = (mass of product actually made / maximum theoretical mass of product) × 100
• If a scientist produced 150 grams of magnesium sulfate from 48 grams of magnesium, what is the percentage yield?

  62.5%
• What happens if the calculation for percentage yield results in a value greater than 100%?

  It indicates a calculation error, as yields cannot exceed 100%
• What are some reasons for not achieving 100% yield in a chemical reaction?

  • Product loss during separation
  • Reactants reacting in unexpected ways
  • Reversible reactions not going to completion
• What is the relative atomic mass of magnesium used in the calculations?

  24
• How do you calculate the number of moles of magnesium from its mass?

  By dividing the mass by the relative atomic mass
• If you have 48 grams of magnesium, how many moles do you have?

  2 moles
• What is the relationship between moles of magnesium and moles of magnesium sulfate produced?

  • 1 mole of magnesium produces 1 mole of magnesium sulfate
• What is the formula to calculate percentage yield?

  Percentage yield = (mass of product actually made / maximum theoretical mass of product) × 100
• Why can the percentage yield never exceed 100%?

  Because it would mean that atoms were created, which is impossible.
• How do you calculate the number of moles from mass and relative atomic mass?

  • Number of moles = mass / relative atomic mass
• If a scientist reacted 130 g of zinc, how many moles of zinc are produced?

  2 moles of zinc.
• What is the maximum theoretical mass of copper that can be produced from 2 moles of zinc?

  127 g of copper.
• What is the percentage yield if 25.4 g of copper is produced from a maximum theoretical mass of 127 g?

  20%.
• What is the relative atomic mass of barium?

  9
• How many moles of barium are produced from 27 g of barium?

  3 moles of barium.
• What is the maximum theoretical mass of barium chloride that can be produced from 3 moles of barium?

  240 g of barium chloride.
• If 144 g of barium chloride is produced, what is the percentage yield from a maximum theoretical mass of 240 g?

  60%.
• What factors can cause the percentage yield to be less than 100%?

  • Incomplete reactions
  • Side reactions
  • Loss of product during transfer
  • Measurement errors