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CBSE Class 10 Science 2019 Outside Delhi Set 3

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Question : 9 of 12
Marks: +1, -0
Given below are the steps for the extraction of copper from its ore. Write the chemical equation of the reactions involved in each case.
(i) Roasting of copper(I) sulphide.
(ii) Reduction of copper(I) oxide from copper(I) sulphide
(iii) Electrolytic refining.
Solution:  
(i) 2Cu2S(s)Copper(I) sulphideCopper glance ore+3O2(g)Oxygen(From air)→Roasting2Cu2O(s)Copper (I) oxide+2SO2(g)Sulphur dioxide\underset{\underset{\text{Copper glance ore}}{\text{Copper(I) sulphide}}}{2\mathrm{Cu}_2\mathrm{S}(\mathrm{s})} + \underset{\text{Oxygen(From air)}}{3\mathrm{O}_2(\mathrm{g})} \xrightarrow{\text{Roasting}} \underset{\text{Copper (I) oxide}}{2\mathrm{Cu}_2\mathrm{O}(\mathrm{s})} + \underset{\text{Sulphur dioxide}}{2\mathrm{SO}_2(\mathrm{g})}
(ii) 2Cu2O(s)Copper(I) oxide+Cu2S(s)Copper sulphide→Heat6Cu(s)Copper metal+SO2(g)Silphur dioxide\underset{\text{Copper(I) oxide}}{2\mathrm{Cu}_2\mathrm{O}(\mathrm{s})} + \underset{\text{Copper sulphide}}{\mathrm{Cu}_2\mathrm{S}(\mathrm{s})} \xrightarrow{\text{Heat}} \underset{\text{Copper metal}}{6\mathrm{Cu}(\mathrm{s})} + \underset{\text{Silphur dioxide}}{\mathrm{SO}_2(\mathrm{g})}
(iii) (a) At cathode :
Cu2+Copper ionFrom electrolyte+2e−ElectronsFrom cathode→CuCopper(Deposits on cathode)\underset{\underset{\text{From electrolyte}}{\text{Copper ion}}}{\mathrm{Cu}^{2+}} + \underset{\underset{\text{From cathode}}{\text{Electrons}}}{2e^{-}} \rightarrow \underset{\text{Copper}_{(\text{Deposits on cathode})}}{\mathrm{Cu}}
(b) At anode :
CuCopper atom(From impure anode)  −  2e−Electrons(Given to anode)→Cu2+Copper ion(Goes into electrolyte)\underset{\text{(From impure anode)}}{\underset{\text{Copper atom}}{\mathrm{Cu}}} \; - \; \underset{\underset{\text{(Given to anode)}}{\text{Electrons}}}{2e^{-}} \rightarrow \underset{\underset{\text{(Goes into electrolyte)}}{\text{Copper ion}}}{\mathrm{Cu}^{2+}}
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