Chemistry Form 4: Chapter 6 - Electrolysis of Concentrated of Sodium Chloride Solution

Electrolysis of dilute sodium chloride solution		Electrolysis of concentrated sodium chloride solution
At anode :	Anions :  OH-   and   Cl- OH- ions are selectively discharge according to the position of ions in the Electrochemical Series, ES.  Gas bubbles are formed which lighted up a glowing wooden splinter. This gas is oxygen. 4OH- ---> 2 H2O  +  O2   +  4e	At anode :	Anions :  OH-   and   Cl- Cl- ions are discharged instead of OH- because of their higher concentration in the electrolyte. A greenish-yellow gas with a pungent and choking smell is released. The gas turns the blue litmus paper red and then white. 2Cl-  --->  Cl2    +     2e
At cathode:	Cations :  H+   dan   Na+ H+ ions are selectively discharge according to the position of ions in the ES. Gas bubbles are formed. When a lighted wooden splinter is placed near the mouth of   the test tube, a ‘pop’ sound is produced.  Hydrogen gas is produced         2H+   +   2e ---> H2	At cathode:	Cations :  H+   dan   K+ H+ ions are selectively discharge according to the position of ions in the ES. Gas bubbles are formed. When a lighted wooden splinter is placed near the mouth of the test tube, a ‘pop’ sound is produced.  Hydrogen gas is produced     2H+   +   2e ---> H2