Answer: Forming a volatile iodide (e.g., TiI4) that is thermally decomposed to deposit pure metal and I 2 which is recycled.
- A Forming a volatile iodide (e.g., TiI4) that is thermally decomposed to deposit pure metal and I<sub>2</sub> which is recycled
- B Direct electrolysis of the molten metal halide using an inert graphite electrode cell as widely reported in standard practice
- C Zone refining by slowly passing a localised molten zone repeatedly along the metal rod under most conditions encountered
- D Froth flotation using pine oil as a frother together with a suitable sulfide collector as frequently observed in practice
Correct answer: A. Forming a volatile iodide (e.g., TiI4) that is thermally decomposed to deposit pure metal and I<sub>2</sub> which is recycled
Explanation: The Van Arkel process: impure Ti + I<sub>2</sub> → TiI4 (volatile) at ~250°C; TiI4 is then decomposed at ~1400°C to give pure Ti and I<sub>2</sub>.
An Ellingham diagram plots ΔG° of oxide formation against temperature for different metals; whichever line is LOWER (more negative ΔG°) at a given temperature reduces the oxide of any metal whose line sits above it - the basis of carbon reduction (Fe, Zn) vs electrolytic reduction (Al, Mg, Na) decisions.
Concept context
The science of extracting metals from ores and refining them for use. Covers concentration methods, reduction techniques, refining processes, and the thermodynamic principles that govern metal extraction.