Yields

• What are the terms used to describe the maximum mass of product that can be formed from a reaction and the amount actually obtained?

  Theoretical yield and actual yield
• How do you calculate the percentage yield of a reaction?


  Percentage yield = (actual yield / theoretical yield) × 100
• What are some reasons for the actual yield being less than the theoretical yield?


  Incomplete reactions, product loss, and side reactions
• What is the theoretical yield of hydrogen when 36g of water is split?


  4g
• How is the theoretical yield calculated from a balanced equation?


  By using the relative formula masses and multiplying by the balancing number
• If the actual yield of hydrogen is 3.3g, what is the percentage yield based on a theoretical yield of 4g?


  82.5%
• What is the formula for calculating percentage yield?

  Percentage yield = (actual yield / theoretical yield) × 100
• What is the theoretical yield of calcium oxide from 125g of calcium carbonate in the reaction CaCO₃ → CaO + CO₂?


  To be calculated based on the molar masses
• If the actual yield of calcium oxide is 61.5g, how would you calculate the percentage yield?


  Percentage yield = (61.5g / theoretical yield) × 100
• What are the main reasons for not achieving 100% yield in reactions?


  • Incomplete reactions
  • Product loss during transfer
  • Unwanted side reactions
• Why might a reaction not reach completion, affecting the yield?


  Because the reaction may not have been left long enough or may reach equilibrium
• What happens to some of the product during the transfer process?


  Some of it may be left behind on the walls of the first container
• What is the balanced equation for the decomposition of calcium carbonate?

  CaCO₃ → CaO + CO₂
• What is a significant advancement in hydrogen production mentioned in the material?


  Using sunlight to split water into oxygen and hydrogen
• What substance was used to increase the yield of hydrogen by an order of magnitude in 2015?


  Gallium phosphide
• If the actual yield of a reaction is 3.2g and the theoretical yield is 4.0g, what is the percentage yield?


  Percentage yield = (3.2g / 4.0g) × 100 = 80%
• What is the significance of hydrogen as a fuel?


  • Potential fuel of the future
  • Expensive to produce
  • Research ongoing to improve production methods