Question

Give an example of a sulphide ore which reduced to metal by heating alone i.e by roasting

Answer 1

Hint: We have to know metals are gotten from oxide minerals after passing through the reduce or electrolysis process. While oxide ores are not difficult to diminish it isn't something similar with sulfides and carbonates. These ores can be gone to metals solely after changing carbonates and sulfides over to an oxide metal.

Complete answer:
At the point when we talk about roasting, it is essentially an interaction of metallurgy where metal is changed over into its oxide by warming it beneath its melting point within the sight of more amount of air. While calcination is generally utilized in the oxidation of carbonates, roasting is a technique that is utilized for changing over sulfide minerals. During roasting, dampness and non-metallic contaminations as volatile gases are liberated. Method of roasting comprises solid gas heat reaction which incorporates oxidation, pyro hydrolysis, reduction, chlorination and sulfation.
Nonetheless, roasting which includes sulfides is a significant source of air contamination and the primary disadvantage of this interaction is that it delivers a lot of metallic and poisonous and acidic substances which distress the climate.
We can say that cinnabar is a sulfide ore which is reduced to metal by the process of heating. We have to know that cinnabar is first converted to mercuric oxide. The mercuric oxide is reduced to mercury by heating. We can write the chemical reactions are,
$2HgS\left( s \right) + 3{O_2}\left( g \right) + Heat \to 2HgO\left( s \right) + 2S{O_2}\left( g \right)$
$2HgO\left( s \right) + Heat \to 2Hg\left( l \right) + {O_2}\left( g \right)$
An example of a sulphide ore that is reduced to metal by heating is Cinnabar.

Note:
We have to remember that roasting is mainly done for minerals composed of sulfide. In roasting, dehydration of ore does not take place. At the time of roasting, huge quantities of metallic and acidic compounds which are extremely toxic are eliminated/liberated.