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Question
Give the steps involved in the extraction of metals of low and medium reactivity from their respective sulphide ores.
Solution
In the extraction of metal from their sulphide ores, the ore is first kept for the process of roasting in which it is heated in the presence of air below its melting point to convert the sulphide ore to its oxide form.
For example, Cinnabar is heated in the air which mercuric sulphide gets oxidised to produce mercuric oxide.
`2"HgS" + 3"O"_2 -> 2"HgO" + 2"SO"_2`
Mercuric oxide is further reduced by heating to get pure mercury.
`2"HgO" -> 2"Hg" + "O"_2`
In the case of zinc which is a metal of medium reactivity and its ore is zinc blende.
Zinc blend is roasted to get zinc oxide.
`2"Zns" + 3"O"_2 -> 2"ZnO" + 2"SO"_2`
When zinc oxide is reduced in the presence of coke, pure zinc metal is produced.
`"ZnO" + "C" -> "Zn" + "CO"`
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