Jeff Rigby wrote:

Water dissociates creating the same amounts of H+ and OH- ions. First
are connected with solution acidity, the latter with solution basicity.
Thus water is acidic and basic - to the same extent - at the same time.
That's why pure water is neutral.

I understood that water does NOT disassociate, it's a very stable and strong
bond, EXTREMELY strong bond, it's equalibrium reaction has very few
disassocited ions.

H2O - H+ + OH-

You are right that equilibrium for this reaction is far to the left -
ie water is dissociated only slightly, but nonetheless it is
dissociated and it can't be neglected whenever we are talking about pH
of solutions, especially those close to the neutral. Note, that pH =
-log([H+]) - if pure water has pH = 7 there MUST be some free H+ ions
in the solution, and they come just from water autodissociation. If you
think that 10^-7 is so low concentration that it can be neglected,
think about pH indicators - some of them change color just because
concentration of H+ changes from 10^-7 to 10^-8 mol/L. So these pretty
small changes in concentrations can produce large effects. Which is -
BTW - one of the reasons why some people want to precisely monitor pH
of oceans

It's geometry, were oxygen and hydorgen atoms are placed
in the molecule allow the water moleule to have a strong charge at each end
where the oxygen has a - charge and the Hydrogen has + charge.

Yep, water molecule is a dipole.

It ionizes molecules because of this GEOMETRY not because water disassociates.

These are two completely different things. Autodissociation of water is
one thing, dissociation of salts - induced by water properties - is
second thing. Don't mix them.

Pure water can not carry a charge! Try for yourself, put two electrodes in
distilled water and try to run a current thru water, you won't get one
untill you introduce a compound that can be ionized to carry the current.
If pure water can not carry a charge then it is not disassociated. You can
crack the water molecule with enough voltage but it doesn't ionize it cracks
and releases hydrogen gas and oxygen gas.

Ultrapure water has very high resistivity, something like 18MOhm/cm,
that's right. But it doesn't mean it is not dissociating

Borek
--
http://www.chembuddy.com
http://www.ph-meter.info