[water]

Strange question, just curious-- how could I separate one molecule of water and store it in a vial?

[Honclbrif]

Do you want to take one individual molecule of water, separate it from the bulk liquid, and store it in a vial?

You might be able to do some sort of statistical dilution of water vapor, but I don't imagine it would be very easy or reliable. Furthermore, the difficulty would be compounded by the ubiquitousness of water in the enviroment, so you would need some specialized equipment to keep extraneous water out of your system. Finally, it wouldn't really look like anything more than an empty vial.

[water]

Thank you. I have no chemistry background though I'm somewhat versed. Could you explosn a statistical dilution of water vapor in laymens terms? It sounds like it's impractical without equipment but I'm still curious about what something like that would entail.

[water]

*explain

and yes I want to have a vial containing 1 molecule of water. It's
conceptual, no scientific application.

[fledarmus]

What else do you want in the vial? Total vacuum? Perfectly dry (well, except for the one water molecule) air? Some sort of solvent, like ether, methanol, DMF?

A statistical dilution simply means diluting a known number of molecules until statistically there is only one in your volume. For example, a sample of water weighing 18.015 g (1 mole), would have 6.023x10²³ molecules, and at standard temperature and pressure (assuming it behaves as an ideal gas) would occupy 22.4 liters. If you take 2.24 liters out of that, and expand it to 22.4 liters, you have diluted it ten-fold, and now have 6.023x10²² molecules. Rinse and repeat until you are down to 1 molecule.

[Borek]

A statistical dilution simply means diluting a known number of molecules until statistically there is only one in your volume. For example, a sample of water weighing 18.015 g (1 mole), would have 6.023x10²³ molecules, and at standard temperature and pressure (assuming it behaves as an ideal gas) would occupy 22.4 liters. If you take 2.24 liters out of that, and expand it to 22.4 liters, you have diluted it ten-fold, and now have 6.023x10²² molecules. Rinse and repeat until you are down to 1 molecule.

While in a way you are right, assuming water is gas at STP is rather unusual.

[Arkcon]

Sometimes, chemists do isolate and visualize a single atom or ion, and I assume molecule, although I haven't heard of that one.  Such things make great photos, and you'll hear about them on the news, or read about them in Popular Science, or Scientific American, or Discovery or other such magazine sources.  These sorts of things are cool, but I don't pay a lot of attention to them, because like you've said, there isn't a lot of practical use.  So I can only give you the above hints to where to look, not specifics.  Thing is, those visualizations of trapped single atoms are happening deep inside a large expensive machine, using high powered laser and magnetic fields and things like that.  What you're asking for, a single molecule, in a pressurized gas or a vacuum, in a vial, that you can hold -- I don't think that's been done.

[Fluoroantimonicacid]

I think this water molecule will be in gas form, it can't make H-bonds alone.