when we do the electrolysis of NaCl then chlroine will formed into gaseous state and hence get removed from the solution the remain metal is Na(sodium) so my question is that sodium is a metal that burns in water so after this reaction why sodium is not burning even though it is in water?

Asked by krishdabhoya2003 | 19th Aug, 2018, 11:34: AM

Expert Answer:

There are two way we performed electrolysis of NaCl
1) Molten NaCl or Concentrated NaCl solution:
In the electrolysis the electrolyte is obtained by heating the solid form of NaCl, on the heating state of NaCl is changes from solid to liquid which is our electrolyte.
Hence there are only two ions are present in the solution i.e., Na+ and Cl-.
Hence at cathode:
 Na+ + e- → Na
At anode: 
 Cl- - e- → Cl 
Cl + Cl → Cl2
2) Aqueous NaCl solution or brine solution:
The electrolyte is obtained by mixing water and NaCl salt. Hence there are four ions present i.e. Na+, Cl-, H+, OH-.
At cathode: 
H+ + e- → H
H + H → H2
At anode:
Cl- - e- → Cl
Cl + Cl → Cl2
Other remaining ions Na+ and OH- are combined to formed NaOH.
Hence if an aqueous solution of NaCl is electrolyzed it will never be discharged sodium metal at cathode instead that hydrogen gas is discharged there.
Because Hydrogen is lower in the electrochemical series than sodium, hence it will discharge more easily at the cathode.

Answered by Ramandeep | 20th Aug, 2018, 12:55: PM