Question 1: Aluminium is extracted from bauxite ore using the Hall-Héroult process, which involves the electrolysis of aluminium oxide dissolved in cryolite. This process requires high temperatures and electrical energy to separate aluminium metal from oxygen ions.

Answer: The Hall-Héroult process uses electrolysis of aluminium oxide in cryolite to produce aluminium metal, requiring high temperature and electrical energy.

Question 1: Define electrolysis and explain its role in aluminium extraction.

Answer: Electrolysis is a chemical process that uses electricity to break down compounds into their elements; in aluminium extraction, it separates aluminium metal from aluminium oxide.

Question 2: What is the purpose of cryolite in the electrolysis of aluminium oxide?

Answer: Cryolite lowers the melting point of aluminium oxide, enabling electrolysis to occur at manageable temperatures.

Question 1: Calculate the amount of electrical charge (in coulombs) required to produce 10 kg of aluminium, given that the electrolysis of aluminium oxide consumes 1.2 F (Faraday) per mole of aluminium. (Molar mass of Al = 27 g/mol, 1 Faraday = 96485 C)

Answer: Charge = (Mass of Al / Molar mass of Al) × 1.2 × 96485 C = (10000 g / 27 g/mol) × 1.2 × 96485 C ≈ 4.07 × 10^6 C

Question 1: Describe a basic experimental setup to demonstrate electrolysis in a school laboratory, including safety precautions students should follow.

Answer: An experimental setup involves electrodes immersed in an electrolyte solution of aluminium oxide in cryolite, connected to a power supply. Safety precautions include wearing eye protection, handling chemicals with care, ensuring proper ventilation, and avoiding contact with electrical components.

Question 1: During a trial, 250 A of current was passed through the electrolyte for 3 hours. How much aluminium (in kg) was produced? (Use F = 96485 C, molar mass of Al = 27 g/mol, 3 electrons per atom of aluminium).

Answer: Total charge Q = current × time = 250 A × (3 × 3600 s) = 2,700,000 C. Moles of Al = Q / (3 × 96485 C) ≈ 9.33 mol. Mass of Al = 9.33 mol × 27 g/mol ≈ 252 g ≈ 0.252 kg.

Question 1: Describe the main environmental and economic advantages of using electrolysis for aluminium extraction compared to traditional methods.

Answer: Electrolysis allows for large-scale, pure aluminium production with less pollution if properly managed. Economically, it enables aluminium to be produced from bauxite efficiently, supporting industries like aerospace and packaging, though it requires significant energy input, which can be costly and environmentally impactful.

Question 1: Explain how advances in electrolysis technology could reduce the carbon footprint of aluminium production in the future.

Answer: Developing renewable energy-powered electrolysis plants and improving energy efficiency can significantly reduce greenhouse gas emissions associated with aluminium production.