H2O question?

Question

Single water molecules can dissociate into hydrogen and hydroxide ions by themselves TRUE OR FALSE

WHY??

I think that the answer is FALSE. It is the "by themselves" that is throwing me off!

Answer 1

Water is never all H2O ... the molecules do disassociate into hydroxide (HO) and hydrogen. The uncombine and combine at all times faster than is visually detectable

Answer 2

TRUE!!!!!

Reason, water of itself undergoes an equilibrium reaction.
Water dissociates into H+ and OH- ions, but under the rules of equilibrium reactions these ions re - associate to form a water molecule again. It is a dynamic process. As one molecule is dissociating another is re-associating.
On putting one's hand into water we do not feel it to be an acid because this equilibrium process is only form a small number of H+ & OH- ions, and secondly the charges between acid(+) and alkali(OH-) balance - there are an equal number of each type of ion present.
H2O <=> H+ + OH-
So overall the charge remains neutral.

De-ionised water, is water were this equilibrium process is briefly stopped.

Answer 3

single water molocules CANNOT dissociate into hydroxide and hydrogen ions BY THEMSELVES.
This is because in order to dissociate, the water molocule needs another molocule to 'pull' it apart. It woud never split itself up like that in normal conditions.
The water molocule needs other water molocules (or another polar solvent) to help it dissocate. (water molocules attract other water moloucles as they have an uneven distribution of electrical charge along the whole molocule. The postitve end of the water molocule (the two hydrogen ends sticking out) would attract the negative end of the molocule (the oxygen end) and vice versa)
In pure liquid water, water molocules do dissociate with the help of other water molocules. However, this does not occur often (about 1 in every 1000 molocules) as the bond is quite strong compared to the pulling force of the other water molocules)
PS: the term hydrogen ions is in actual fact wrong. The actual term is hydroxonium ion, H3O+. However, this term can be still used in everyday conversations with ordinary people.

Answer 4

Water (H2O) is in constant equilibrium with OH- and H+ where the conc of OH- and H+ leading to a pH value of 7 and therefore their conc's are the same. So yes is does it on it's own but it is a dynamic equilibrium so once the system has reached equilibrium each time a H20 molecule dissociates one OH- and one H+ combine to form H2O.