Question 1: Define electrolysis and explain its role in the extraction of aluminium from bauxite ore.

Answer: Electrolysis is a chemical process that uses an electric current to break down compounds into their elements. In aluminium extraction, electrolysis is used to convert aluminium oxide into pure aluminium metal.

Question 2: What is the main raw material used in the industrial extraction of aluminium, and what is its chemical formula?

Answer: The main raw material is bauxite, which contains aluminium oxide, with the chemical formula Al₂O₃.

Question 3: Describe the purpose of adding cryolite during the electrolysis of aluminium oxide.

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

Question 4: Calculate the amount of electric charge (in coulombs) needed to produce 10 grams of aluminium, given that 1 mole of aluminium (26.98 g) requires 3 Faradays of charge.

Answer: First, find moles of aluminium: 10 g / 26.98 g/mol ≈ 0.3707 mol. Each mole requires 3 Faradays, and 1 Faraday = 96,485 C. Total charge = 0.3707 mol × 3 × 96,485 C ≈ 107,439 C.

Question 5: Identify the two main products formed at the electrodes during aluminium electrolysis.

Answer: At the cathode: aluminium metal; at the anode: oxygen gas.

Question 6: Explain why carbon anodes are used in the electrolysis process of aluminium extraction and what happens to them over time.

Answer: Carbon anodes are used because they conduct electricity and react with oxygen to produce carbon dioxide. Over time, the anodes are consumed as they react with oxygen at the anode to form CO₂ gas, which means they need to be replaced regularly.

Question 7: Which safety precautions should be considered when performing electrolysis of aluminium in industry? List at least three.

Answer: Wearing protective gear (gloves, goggles), ensuring proper ventilation, and handling electrical equipment carefully to prevent shocks.

Question 8: Fill in the blank: The process of extracting aluminium using electrolysis is classified as a ________ chemical change because it involves breaking down compounds into elements using electricity.

Answer: chemical

Question 9: Describe a practical industrial step involved in the aluminium extraction process, focusing on the preparation of raw materials.

Answer: The raw bauxite ore is first crushed and then refined through the Bayer process to produce pure aluminium oxide, which is then mixed with cryolite before electrolysis.

Question 10: In the context of aluminium extraction, what is meant by the term 'electrolyte' and why is it important?

Answer: An electrolyte is a substance that conducts electricity when molten or dissolved in water. In aluminium electrolysis, the electrolyte (containing aluminium oxide and cryolite) allows current to pass through and facilitates the chemical reaction.

Question 11: Considering environmental impacts, discuss one challenge associated with the industrial extraction of aluminium and a potential solution.

Answer: One challenge is the emission of carbon dioxide from the carbon anodes, contributing to greenhouse gases. A potential solution is developing alternative anode materials that do not produce CO₂ or capturing and reusing emissions.