Question

Write information of compounds of sodium-1.NaCl,2.Na2Co3
Also right information about casting process and electrolyte process and also write what is anode cathode and what will be the electrolyte

Answer 1

Answer:

hope this will help u

Explanation:

Castner's Process

In this process, electrolysis of fused sodium hydroxide is carried out at 330°C using iron as cathode and nickel as anode: 2NaOH \rightleftharpoons 2Na+ + 2OH

At cathode : 2Na+ + 2e   →   2Na

At anode: 4OH- →  2H2O + O2 + 4e

During electrolysis, oxygen and water are produced.

Water formed at the anode gets partly evaporated and is partly broken down and hydrogen is discharged at cathode : H2O \rightleftharpoons H+ OH-

At cathode: H+ + 2e →  2H  H2

Castner's process:  

Castner's process

At cathode

At anode

Overall  

2Na+ + 2e  →  2Na &  

H+ + 2e →  2H  H2

4OH- →  2H2O + O2 + 4e

2NaOH\Leftrightarrow 2Na+ + 2OH

Down's Process

Now-a-days sodium metal is manu­factured by this process.

It involves the electrolysis of fused sodium chloride containing calcium chloride and potassium fluoride using iron as cathode and graphite as anode at about600oC.

Down's process:

NaCl \rightleftharpoons Na+ + Cl-

At cathode: Na+ + e  → Na

At anode: 2Cl-  →  Cl2 + 2e

The electrolysis of pure NaCl presents the following difficul­ties:

(i) The fusion temperature of NaCl is high, i.e., 803°C. At this temperature both sodium and chlorine are corrosive.

(ii) Sodium forms a metallic fog at this temperature.

To remove above difficulties, the fusion temperature is reduced to 600°C by adding CaCl2 and KF.  

This is a cheaper method and chlorine is obtained as a by-product. The sodium obtained is of high purity (about 99.5%).

Down's process

At cathode

At anode

Na+ + e  → Na

2Cl-→  Cl2 + 2e

Sodium Hydroxide (Caustic soda), NaOH

Caustic soda is manufactured by the electrolysis of aqueous solution of sodium chloride in an electrolytic cell.

Principle

A sodium chloride solution contains Na+, H+, Cl- and OH- ions.

NaCl  \rightleftharpoons Na+ + Cl-

H2O \rightleftharpoons H+ + OH-

On passing electricity, Na+ and IF ions move towards cathode and CI- and OH" ions move towards anode.

The discharge potential of H+ ions is less than Na+ions, thus hydrogen ions get discharged easily and hydrogen is liberated. Similarly, at anode CI- ions are easily discharges as their discharge potential is less than that of OH- ions. Cl2 gas is, therefore, liberated at anode.

The solution on electrolysis becomes richer in Na+ and OH- ions.

Since chlorine reacts with sodium hydroxide solution even in the cold forming sodium chloride and sodium hypochlorite, it is necessary that chlorine should not come in contact with sodium hydroxide during electrolysis. 2NaOH + Cl2 →  NaCl + NaCIO + H2O

To overcome this problem, the anode is separated from the cathode in the electrolytic cell either by using a porous diaphragm or by using a mercury cathode.

Porous Diaphragm Process (Nelson Cell Process)

Nelson cell consists of a perforated steel tube lined inside with asbestos. The tube acts as a cathode (Fig. 12.19).

Porous Diaphragm Process (Nelson Cell Process)

It is suspended in a steel tank.

A graphic rod dipped in sodium chloride solution serves as anode.

On passing electric current, chlorine is liberated at the anode and let out through the outlet.

Sodium ions penetrate through the asbestos and reach the cathode where hydrogen and OH- ions are formed by reduction of water.

Sodium ions combine with OH- ions to form NaOH which is collected in the outer tank while hydrogen is drawn off through the outlet.

The steam blown during the process keeps the electrolyte warm and helps to keep perforation clear.

At Cathode   2H2O+2e  \rightleftharpoons H2 + 2OH-  & Na+ OH- \rightleftharpoons NaOH

At anode     2Cl- →  Cl2 + 2e

The solution containing NaOH and Nacl as impurity is taken out and evaporated to dryness.

Nelson cell process

At cathode

At anode

2H2O+2e  \rightleftharpoonsH2 + 2OH-  & Na+ OH- \rightleftharpoons NaOH

2Cl-→  Cl2 + 2e