Question

how NaOH is prepared
Explain briefly pls
I will mark as brainliest​

Answer 1

Various methods of preparation of sodium hydroxide are -

Castner — Kellener Process

Principle — In castner-kellner method NaOH is prepared by the electrolysis of aqueous solution of NaCl (Brine).

Castner-kellner cell — It is a rectangular tank of steel. Inside of tank is lined with ‘ebonite.’ Anode is made of titanium. Flowing layer of mercury (Hg) at the bottom of tank serves as cathode.

Ionization of NaCl — 2NaCl e- 2Na+ + 2Cl-

When electric current is passed through brine, +ve and -ve ions migrate towards their respective electrodes. Na+ ions are discharged at mercury cathode. The sodium deposited at mercury forms Sodium Amalgam. Chlorine produced at the anode is removed from the top of the cell.

Reaction at cathode

2Na+ +2 e- à 2Na

(Na forms amalgam)

Na + Hg à Na/Hg

Na+ ions are discharged in preference to H+ ions due to high over voltage.

Reaction at anode

2Cl- à Cl2 + 2e-

Formation of NaOH

Amalgam moves to another chamber called ‘denuder,’ where it is treated with water to produce NaOH which is in liquid state. Solid NaOH is obtained by the evaporation of this solution.

2Na/Hg + 2H2O à 2NaOH + H2 + 2Hg

NaOH obtained is highly pure and the process is very effeicient.

Answer 2

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