Electrolysis of water

  • 1 Replies

0 Members and 1 Guest are viewing this topic.


Offline cuso4

  • Angel Delight
  • Sr. Member
  • ****
  • 422
    • View Profile
Electrolysis of water
« on: 25/04/2003 09:36:44 »
In electrolysis, the electrode attracts the ions in the aqueous solution. ie this only works with ionic compound. So is it true to say that water cannot be electrolysed?

AG, puzzled AS chem student[?]


Offline NakedScientist

  • Moderator
  • Sr. Member
  • *****
  • 355
    • View Profile
    • http://www.thenakedscientists.com
Re: Electrolysis of water
« Reply #1 on: 25/04/2003 10:24:02 »
When chemistry teachers want to electrolyse water in the classroom to make hydrogen and oxygen in a Hoffman Voltameter (the H shaped piece of apparatus with 2 platinum electrodes at the base of 2 tall burettes), they add a bit a sulphuric acid to the water to provide some 'ions' to convey the current. Otherwise the electrolysis would go so slowly that you'd hardly collect any gas.

In reality you CAN electrolyse water because it DOES ionise to a small degree producing H3O+ and OH- ions which carry the charge when you apply a potential difference. Because the equilibrium lies far to the left (mostly unionised) electrolysis is 'difficult' and hence teachers facilitate the process with the sulphuric acid.

hope this helps