You scare me a little, because of how knowledgeable you seem to a layman and yet how wrong you are.
At the molecular scale, water molecules don't just decide to break up and go their own way willy-nilly...
Yes, they do, and it's called equilibrium. This probably the most fundamental concept of high school chemistry. Water molecules continually break into H+ and OH- ions and reform themselves from those ions. You'll find that when perfect equilibrium is reached, the product of their molarities (that's the moles solute per liter solvent) is 10^-7. That's where we get the neutral pH 7 from. Look it up here
. Fascinating stuff. ...not the least because both elements involved (hydrogen and oxygen) really don't like being alone (the two hydrogen atoms can go off on their own merry way as a diatomic molecule, but the oxygen will be lonely).
Please stop pretending to know what you're talking about; you clearly have no concept of even ionic bonding. Water would never split that way unless you run a hydrolysis reaction (running an electric current through the water). Water ALWAYS splits into H+ and OH- ions. Read that sentence again; it's important. They are IONIC BONDS. You seem to think they are covalent. When water dissociates (that means splits, see equilibrium above), those ions HAVE to stay in solution. H+ DOES NOT bond with another H+ to form H2. Neither does the oxygen.
Breaking molecular bonds in water takes energy
Really? Then why does salt dissolve in water? EQUILIBRIUM.
Cracking water is endothermic, but so is making it
AARGH. Then water would not exist! The heat of formation is ALWAYS the opposite of the heat of decomposition. Please, I'm begging you, take a chemistry course. Your sophomore one does not count, but you obviously slept through it anyway.
and a net change in the number of water molecules, of zero.
YES! Good job! That's perfect equilibrium. The grandparent had the right idea about equilibrium, although he failed to realize that since there is a net change of zero, the mass also does not change. Ions do not leave solution, nor does their mass magically disappear.
Mr. McGuire: I want to say one word to you. Just one word.
Benjamin: Yes, sir.
Mr. McGuire: Are you listening?
Benjamin: Yes, I am.
Mr. McGuire: Plastics.
This is a fundamental property of water - it is INCOMPRESSIBLE. See here
. You know nothing about chemistry. Stop, stop, stop.
Last, but not least: evaporation
Last, but not least: sealed container.
Very easy, actually; the problem is maintaining its purity after it cools down from superheated steam.
Solutes dissolve MORE in superheated water.
I don't know who you are. I don't know much about you. But I do know that you know nothing about chemistry. I know this is
/., but STOP. STOP. STOP. People might actually believe you.