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प्रश्न
Write the chemical reactions involved in the extraction of gold by cyanide process. Also give the role of zinc in the extraction.
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उत्तर
\[\ce{4Au(s) + 8CN^{-} (aq) + 2H2O (aq) + O2(g) -> 4[Au(CN)2]^{-} (aq) + 4OH^{-} (aq)}\]
\[\ce{2[Au(CN)2]^{-} (aq) + Zn(s) -> 2Au(s) + [Zn(CN)4]^{2-} (aq)}\]
Zinc places the role of a reducing agent. It reduces \[\ce{Au+}\] to pure \[\ce{Au}\].
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संबंधित प्रश्न
Write the names and chemical formulae of any one ore of zinc.
What is the chemical composition of malachite?
- CuO . CuC03
- Cu(OH)2 CuC03
- CuO.Cu(OH)2
- Cu2O . Cu(OH)2
Fe2O3 is reduced to spongy iron near the top of blast furance by
(A) H2
(B) CaO
(C) SiO2
(D) CO
Draw neat and labelled diagram of Bessermer converter used in the extraction of copper.
What is the role of cryolite in the extraction of aluminium?
What is the role of coke in the extraction of iron from its oxides?
What is the role of silica in the extraction of copper?
Describe the roles of the following: SiO2 in the extraction of copper from copper matte
Which of the ores mentioned can be concentrated by magnetic separation method?
Define leaching.
Describe the role of the cryolite in the extraction of aluminium from pure alumina.
Which among the following statement is correct?
When copper ore is mixed with silica, in a reverberatory furnace copper matte is produced. The copper matte contains ______.
Which of the following options are correct?
(i) Cast iron is obtained by remelting pig iron with scrap iron and coke using hot air blast.
(ii) In extraction of silver, silver is extracted as cationic complex.
(iii) Nickel is purified by zone refining.
(iv) Zr and Ti are purified by van Arkel method.
In the extraction of aluminium by Hall-Heroult process, purified \[\ce{Al2O3}\] is mixed with \[\ce{CaF2}\] to:
(i) lower the melting point of \[\ce{Al2O3}\].
(ii) increase the conductivity of molten mixture.
(iii) reduce \[\ce{Al^{3+}}\] into \[\ce{Al(s)}\].
(iv) acts as catalyst.
Although carbon and hydrogen are better reducing agents but they are not used to reduce metallic oxides at high temperatures. Why?
In the thermite process, the reducing agent is:
Native silver metal forms a water solution complex with dilute solution of Na CN in the presence of
Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true?
