Question 1: Define the term 'reduction' in the context of metal extraction.

Answer: Reduction is a chemical process where a metal oxide or compound gains electrons to form the pure metal.

Question 2: Explain why aluminium is extracted using electrolysis instead of reduction with carbon.

Answer: Aluminium oxide cannot be reduced with carbon because aluminium has a more negative reduction potential, so electrolysis is required to extract aluminium from its ore.

Question 3: Describe the main difference between pyrometallurgy and hydrometallurgy.

Answer: Pyrometallurgy involves high-temperature processes like smelting, while hydrometallurgy uses aqueous solutions to extract metals.

Question 1: A sample of ore contains 5% weight of copper. If 200 grams of ore is processed, how much pure copper (in grams) can theoretically be recovered?

Answer: 10 grams

Question 2: If the energy consumed in electrolysis to extract 1 kg of aluminium is 15,000 kJ, how much energy is needed to extract 250 grams of aluminium?

Answer: 3750 kJ

Question 1: Describe a basic experimental setup to extract zinc from zinc oxide using carbon reduction. Include key variables and safety precautions.

Answer: A crucible containing zinc oxide is heated with carbon (charcoal) at high temperature. Key variables include temperature and amount of carbon; safety precautions involve wearing eye protection, working in a well-ventilated area, and handling hot equipment carefully.

Question 2: Identify three factors that affect the efficiency of the electrolytic extraction of aluminium.

Answer: Purity of the alumina, electrical energy supplied, and temperature of the electrolyte.

Question 1: A sample of ore yields 3 grams of gold after processing. The initial ore weighed 50 grams with a gold content of 0.2%. Calculate the percentage yield of gold in the extraction process.

Answer: 30%

Question 2: In a study, two methods of extracting copper are compared. Method A has a 75% efficiency, while Method B has a 90% efficiency. Which method is more effective, and why?

Answer: Method B is more effective because it has a higher efficiency, meaning more copper is recovered from the same amount of ore.

Question 1: Explain why the choice of extraction method for a metal depends on its reactivity series position.

Answer: Metals higher in the reactivity series (like potassium or magnesium) require more reactive extraction methods such as electrolysis, while less reactive metals (like gold or silver) can be extracted using reduction with carbon or simple methods.

Question 2: Identify a modern industry application where electrolysis is used to extract a metal, and discuss its importance.

Answer: Electrolysis is used in the aluminium industry to produce aluminium metal, which is vital for manufacturing aircraft, packaging, and construction due to its lightweight and corrosion resistance.