Tags: Chlor  Chloride  Chlorine  Cl2  Eisen  Electrolysis  FeCl3  Hydrogen  Iron  Na  NaCl  Natrium  Sodium  
Channel: Science & Technology
Uploaded: May 17, 2008 at 6:09 pm
Author: bla287
Length: 01:37
Rating: 2.71
Views: 409
When electrolysing a solution of NaCl, you'd normally expect water to be oxidized to oxygen and oxonium because of the electrode potentials:Cl2 + 2 e− ⇌ 2 Cl− +1,36 VO2 + 4 H3O+ + 4 e− ⇌ 6 H2O +1,23 VNevertheless, you can "trick out" the potentials by using a graphite anode. The smaller chloride ion can attach to the graphite more easily than the bigger H2O molecule, so the chloride ion will be oxidized to chlorine.However, some of the chlorine produced that way will react with the OH- ions produced by the cathode to form ClO- and Cl- (in succession ClO3- and ClO4- as well), but not all of it, so you can collect some of the chlorine.To prove that chlorine has really been produced, I let it react with iron to form yellow iron(III) chloride (FeCl3).So you don't need to melt NaCl if you want to obtain Cl2 (but you have to if you want to get Na).