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The S-Block Elements

Question
CBSEENCH11007099
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Discuss the extraction of lithium.

Solution

It involves the following steps:
(i) Preparation of lithium chloride: The silicate mineral is crushed to fine powder and then boiled with dilute H2SO4 and filtered to remove insoluble silica (SiO2). The mother liquor is then treated with calculated amount of Na2CO3 to precipitate aluminium and iron as carbonates which are filtered off. The filtrate is then treated with an excess of Na2CO3 to precipitate lithium as Li2CO3. The precipitate is dissolved in HCl to form LiCl.
(ii) Electrolysis of lithium chloride. A mixture of dry lithium chloride and potassium chloride is fused and electrolyzed in an electrolytic cell (Down’s cell). Potassium chloride is added to increase the electrical conductivity and also to lower the melting point from 883K to 723K. The cell is operated at a temperature of about 675-775K and voltage of 8-9 volts is applied.
As a result of electrolysis, the following reactions take place:
LiCl space rightwards harpoon over leftwards harpoon space space space Li to the power of plus space plus space Cl to the power of minus At space cathode colon space space space Li to the power of plus space plus space straight e to the power of minus space space space rightwards arrow space space Li At space anode colon space space space space space space Cl to the power of minus space space rightwards arrow space space space Cl space plus space straight e to the power of minus space space space space space space space space space space space space space space space space space space space space Cl space plus space Cl space rightwards arrow space space space Cl subscript 2
Chlorine gas is liberated at the anode while molten lithium rises to the surface of the fused electrolyte and collects in the cast iron enclosure surrounding the cathode. The metal thus obtained is 99% pure. 

Some More Questions From The s-Block Elements Chapter

Which is the most reactive alkali metal and why?

Why alkali metals do not form M2+ ions?

Name the radio active element in group 1. How does it resemble with the remaining elements of the group?

Why alkali metals are normally kept in kerosene oil?

Why lithium cannot be stored in kerosene?

Why does lithium form complexes?

Why are alkali metal ions diamagnetic and colourless?

Why are alkali metals the most electropositive in nature?

Explain why is sodium less reactive than potassium.

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