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(i) Name the method of refining of metal...

(i) Name the method of refining of metals such as Germanium.
(ii) In the extraction of Al, impure `Al_(2)O_(3)` is dissolved in conc. NaOH to form sodium aluminate and leaving impurities behind. What is the name of this process?
(iii) What is the role of coke in the extraction of iron from its oxides?

Text Solution

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(i) Zone refining method is used for the refining of Germanium. It is based upon the principle. That the impurities are more soluble in molten state than in the solid state of metal.
(ii) `underset("Alumina")(Al_(2)O_(3))+underset(("aq"))(2NaOH) + 3H_(2)O overset(Delta)rarr 2Na underset("Sod. metal al uminate ")([Al(OH)_(4)](aq))`
This process is known as leaching and leaching of bauxite ore is known as Baeyer's process which leaves the undissolved impurity behind.
(iii) Coke reduces iron oxide to iron.
`FeO(s) + C (s) rarr Fe + CO (g)`
The process is known as smelting.
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