Question 1: Define the term 'theoretical yield' in a chemical reaction.

Answer: The maximum amount of product that can be formed from a given amount of reactant, assuming complete reaction with no losses.

Question 2: Explain why the actual yield is often less than the theoretical yield.

Answer: Because of practical losses, side reactions, incomplete reactions, or measurement errors during the experiment.

Question 3: What is meant by 'percentage yield' and how is it calculated?

Answer: Percentage yield is the ratio of actual yield to theoretical yield, expressed as a percentage. It is calculated as (actual yield / theoretical yield) × 100%.

Question 1: A reaction between 10 g of magnesium reacts with excess hydrochloric acid to produce magnesium chloride. The molar mass of magnesium is 24.3 g/mol. Calculate the theoretical yield of magnesium chloride (MgCl₂, molar mass 95.2 g/mol).

Answer: 37.2 g

Question 2: In an experiment, the actual mass of magnesium chloride obtained was 33 g. Calculate the percentage yield.

Answer: 88.7%

Question 3: If 5.0 g of sodium reacts with excess water to produce 8.0 g of sodium hydroxide, what is the percentage yield of sodium hydroxide? (Molar mass Na = 23 g/mol, NaOH = 40 g/mol).

Answer: 62.5%

Question 1: Describe a simple experimental setup to determine the yield of a reaction between zinc and hydrochloric acid. Include safety precautions.

Answer: Set up a conical flask with a known mass of zinc. Add excess hydrochloric acid carefully, wearing safety goggles and gloves. Collect the precipitate or solution, filter if necessary, and weigh the product. Ensure good ventilation and handle acids with care to prevent spills and burns.

Question 1: A chemist reacts 50 g of sodium carbonate with excess acid and obtains 42 g of carbon dioxide. If the theoretical amount of CO₂ that could be produced is 45 g, what is the percentage yield? What might account for the difference?

Answer: The percentage yield is (42/45) × 100% = 93.3%. The difference may be due to incomplete reaction, loss of gas during transfer, or measurement errors.

Question 1: Explain why achieving a high percentage yield is important in industrial chemical manufacturing. (6 marks)

Answer: A high percentage yield indicates efficient use of reactants, reducing waste and production costs. It also ensures maximum product output, which is vital for economic viability and environmental sustainability in industry.

Question 2: A reaction has a theoretical yield of 100 g but an actual yield of 80 g. Calculate the percentage yield and discuss possible reasons for not achieving 100% yield.

Answer: Percentage yield = (80/100) × 100% = 80%. Reasons include incomplete reactions, side reactions, product loss during transfer, or measurement errors.

Question 1: Describe how yield calculations are used in the pharmaceutical industry to ensure cost-effectiveness and efficiency of drug production.

Answer: Yield calculations help determine the amount of raw materials needed and the expected amount of product, reducing waste and costs. High yields ensure efficient manufacturing, quality control, and optimal use of resources.