Grade 12 Chemistry: Percentage Yield

Grade 12 Chemistry: Percentage Yield

Read each question carefully and provide detailed answers. Show all your work for calculation problems.

1. The theoretical yield is the maximum amount of product that can be formed from a given amount of  .

2. The   yield is the amount of product actually obtained from a reaction.

3. Percentage yield is calculated by dividing the actual yield by the theoretical yield and multiplying by  .

1. Explain why the actual yield in a chemical reaction is almost always less than the theoretical yield. Provide at least two reasons.

1. In the reaction 2H₂ + O₂ → 2H₂O, if 10.0 g of H₂ reacts completely, and 80.0 g of H₂O is produced, what is the theoretical yield of H₂O?

1. In an experiment, 25.0 g of calcium carbonate (CaCO₃) is heated to produce calcium oxide (CaO) and carbon dioxide (CO₂). If 12.0 g of CaO is actually produced, what is the percentage yield of CaO? (Molar mass of CaCO₃ = 100.09 g/mol, CaO = 56.08 g/mol)

2. Consider the reaction: 2Al + 3Cl₂ → 2AlCl₃. If 54.0 g of aluminum (Al) reacts with excess chlorine (Cl₂), and 150.0 g of aluminum chloride (AlCl₃) is collected, calculate the percentage yield. (Molar mass of Al = 26.98 g/mol, AlCl₃ = 133.34 g/mol)

1. A percentage yield greater than 100% is impossible under normal laboratory conditions.

2. Impurities in reactants can lead to an artificially high actual yield.