Chemistry - Metallurgy Question with Solution | TestHub
In both calcination and roasting, an ore is converted into its oxide, albeit through different chemical pathways. Calcination is the process in which the ore is heated below its melting point, either in the absence or in a limited supply of air, with the aim of driving off volatile impurities, moisture, water of hydration, and organic matter from the ore. Carbonate, bicarbonate, and hydroxide ores are generally subjected to calcination, which produces the metal oxide after expelling CO₂ or H₂O in the process.
In the process of roasting, concentrated ore is heated strongly, below its melting point, in the presence of air with or without some other additives, in order to bring about desired changes. Generally, sulfide ores are subjected to roasting, where oxides are formed and SO₂ is expelled.
Iron ore metal oxide + gas - 1
Iron ore metal oxide + gas - 2
Gas-1 does not decolorize acidic solution, but Gas-2 can. Select the CORRECT option:
Options:
Answer:
Solution:
In calcination, carbonate ores are heated in absence of air and produce CO₂ gas, which does NOT decolorize acidic KMnO₄.
In roasting, sulphide ores are heated in air and produce SO₂ gas, which decolorizes acidic KMnO₄.
Since Gas-1 does not decolorize KMnO₄, it is CO₂ → calcination process (Process I).
Gas-2 decolorizes KMnO₄, so it is SO₂ → roasting process (Process II).