Question

a. Define metallurgy.

b. Give the method of extraction of metals (eg Hg and Cu) present low in the activity series from their oxide and sulphide ores. Write the balanced chemical equation for the reactions involved in each step
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Answer 1

Answer:

(a) The extraction of metals from their ores and refining them so that, they can be put into use is known as metallurgy.

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(b) (i) When cinnabar (sulphide ore of mercury) is heated in air, it is first converted into HgO. It is then reduced to mercury on further heating.

✒ Reactions involved:-

$\bold{2HgS_{(s)}+3O_{2(g)}\xrightarrow{\text{heat}}2HgO_{(s)}+2SO_{2(g)}}$

$\bold{2HgO_{(s)}\xrightarrow{\text{heat}}2Hg_{(l)}+O_{2(g)}}$

(ii) Similarly, copper can be obtained from $\bold{Cu_2S}$ by just heating in air.

✒ Reactions involved:-

$\bold{2Cu_2S_{(s)}+3O_{2(g)}\xrightarrow{\text{heat}}2Cu_2O_{(s)}+2SO_{2(g)}}$

$\bold{2Cu_2O_{(s)}+Cu_2S_{(s)}\xrightarrow{\text{heat}}6Cu_{(s)}+SO_{2(g)}}$