Question 1: Define electrolysis and explain its role in extracting aluminium from bauxite.

Answer: Electrolysis is a chemical process that uses electric current to break down compounds. In aluminium extraction, it is used to decompose aluminium oxide into aluminium metal and oxygen.

Question 2: Describe the main raw material used in aluminium extraction and its chemical formula.

Answer: Bauxite, which contains aluminium oxide (Al₂O₃).

Question 3: Explain why cryolite (Na₃AlF₆) is added during the electrolysis process.

Answer: Cryolite lowers the melting point of aluminium oxide, making electrolysis more energy-efficient and easier to conduct.

Question 1: Calculate the amount of electric charge (in coulombs) required to produce 10 kg of aluminium, given that 1 mole of aluminium (27 g) requires 3 Faradays of charge. (Faraday constant = 96485 C/mol).

Answer: Charge = (Mass of Al / Molar mass of Al) × 3 × Faraday constant = (10,000 g / 27 g/mol) × 3 × 96485 C/mol ≈ 107,460,000 C

Question 1: Identify three variables that can affect the efficiency of the electrolysis process in aluminium extraction.

Answer: Temperature, electrolyte composition, electric current density.

Question 2: List two safety precautions that should be observed during the electrolysis of aluminium oxide.

Answer: Wearing protective goggles and ensuring proper ventilation due to the release of gases.

Question 1: During an electrolysis experiment, it was observed that the amount of aluminium produced was less than expected despite using the correct amount of electricity. Suggest two possible reasons for this discrepancy.

Answer: Incomplete electrolysis due to impurities in the electrolyte, or energy losses as heat reducing efficiency.

Question 1: Explain the industrial importance of aluminium extraction and discuss two environmental concerns associated with the process. (6 marks)

Answer: Aluminium extraction is vital for producing lightweight, durable metals used in transportation, packaging, and construction. Environmental concerns include high energy consumption leading to greenhouse gas emissions, and the disposal of waste materials like red mud, which can pollute water sources if not managed properly.

Question 1: Describe how advances in aluminium extraction technology could influence the construction industry.

Answer: Improved efficiency and reduced energy costs could make aluminium more affordable, encouraging its wider use in sustainable and lightweight building materials.

Question 2: Suggest one way that industry could reduce the environmental impact of aluminium extraction.

Answer: Implementing renewable energy sources, such as solar or wind power, to supply the electricity needed for electrolysis.