A concentrated ore (X) of a transition metal is roasted in air to produce a gas (G) that turns acidi — Metallurgy and Isolation of Elements Chemistry Question
Question
A concentrated ore (X) of a transition metal is roasted in air to produce a gas (G) that turns acidified $K_2Cr_2O_7$ green. The roasted product undergoes self-reduction at high temperatures to yield a metal that develops a blistered appearance upon cooling. What is the primary chemical identity of ore (X)?
💡 Solution & Explanation
The gas (G) that turns acidified dichromate green is $SO_2$, indicating a sulphide ore. The metal undergoes self-reduction and forms "blisters" due to escaping $SO_2$ gas upon cooling. This is the defining characteristic of Blister Copper, extracted from copper sulphide ores like Copper glance ($Cu_2S$) or Chalcopyrite.