Answer: Roasting.
- A Roasting
- B Calcination
- C Smelting
- D Refining
Correct answer: A. Roasting
Explanation: Roasting heats sulfide ores in excess air; sulfides are converted to oxides with SO<sub>2</sub> as a byproduct.
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.