Dissociation of the Water Molecule

[ramset]

Loner
Your contribution would be Immense here!!  [towards open source]
Chet

[Farrah Day]

Hi Alan

The H3O+ hydronium ion is often ignored in high school electrolysis, and indeed by many other sources of electrolysis info, which brings up my point about electrolysis not itself being quite as simple and easy to understand as we are often led to believe.

As far as I am aware, the hydrogen proton (H+) only exists for a tiny fraction of a second before it reacts with the electron cloud around a molecule, in our case a water molecule, hence H3O+.  Also unlike the hydroxyl ion, the hydrogen ion moves through the water, effectively hoping from one water molecule to the next (or rather displacing another hydrogen proton), in much the same way as electrons move in a conductor. This action is known as the Grotthuss Mechanism and does rely on the clumping, or binding nature or water molecules.

So, with a voltage applied across two electrodes in water, we don't necessarily get the original H+ ion reacting at the cathode, but simply 'a' displaced hydrogen proton.  Because of this, I would expect the hydrogen reaction to be far more efficient than the hydroxyl reaction, given that the hydroxyl ion is much bigger and has to itself physically travel all the way through the liquid environment.

If we compare the H+ movement through water to that of electrons through a conductor, here is a good analogy:

Think of electrons travelling through a conductor as a hollow tube full of touching ball bearings. If the tube is full and you push an additional ball bearing into one end, then a ball bearing will instantly pop out of the other end. It is as good as instantaneous, though it would be sometime, should you continue re-inserting the expelled ball bearing, before the first additional ball bearing you pushed into the tube finally reappeared. 

So, assuming that the hydrogen proton does move in a similar fashion to the electron - although not with the efficiency of the electron - you might certainly expect it to require many times less energy getting from A â€" B than the hydroxyl ion.

Incidentally, I read somewhere that an electron from a mains 240 volt supply travels at around 3 inches in an hour.  I mention this because many people think of electrons as tiny particles whizzing around at near the speed of light â€" this does somewhat give you a rather different perspective of electricity doesn’t it!

The one good thing about all this, is that it’s not just us that are struggling to make sense of the electrochemistry. Scientists are still yet to fully understand all the properties of water, as it seems it does not always behave as predicted under certain conditions.

[ramset]

Speaking of not fully understanding the properties of water

http://www.youtube.com/results?search_type=&search_query=Floating+Water+Bridge&aq=f

posted by a VERY bright young man zerotensor

Chet

PS if you know how this works, call the Physicists working on this [they could use your help]

[Room3327]

Incidentally, I read somewhere that an electron from a mains 240 volt supply travels at around 3 inches in an hour.  I mention this because many people think of electrons as tiny particles whizzing around at near the speed of light â€" this does somewhat give you a rather different perspective of electricity doesn’t it!

@ Farrah Day,
   Yes most people don't realize this, If I recall correctly I think it is 1 Coulomb of electric charge moving through a wire at a rate of 1 amp moves like 4 inches a second. Pretty slow really even though electrons can move close to the speed of light.

[dankie]

Why is this person still allowed to post here ?