Is there a way to let water pour out of bottle without letting air inside? i understand that air needs to enter the bottle to ensure water flow, but i do not want to the water to be exposed to air. Can this be achieved without any sophisticated equipment?
closed as unclear what you're asking by Dilaton, Emilio Pisanty, Manishearth♦ Aug 12 at 13:24
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I am not sure what are you trying to achieve: obtain a vacuum in a bottle or remove water from the bottle without exposing the liquid to the air? Assuming it is the first.
You could heat the bottle to the temperatures slightly greater than 100°C (providing it is water inside the bottle) and letting boiling commence by opening it, keeping the opening small so that the air won't get in and pressure would remain slightly above atmospheric.
Then you could hermetically seal the bottle when most of the liquid boiled away (but some should still be there so that the bottle would still be filled with water vapor at pressure of about 1 atmosphere).
Once thus sealed bottle cooled to room temperature, the bottle will be filled with water vapor (and small amount of remaining+condenced water) which would have pressure of about 2.5kPa -- not exactly vacuum but close enough.
Alternatively, you could attach on top of the bottle long (more than 10 m) tube (glass or metal but not squeezable plastic) and fill whole thing (bottle and the tube) with water. Then slowly rotate the construct allowing water to spill out from the tube in some basin. Once the bottle rises over 10 m (1 atm/($\rho$ g)) it will empty and will be filled with vacuum (again Torricellian vacuum, actually water vapor) -- it is actually Torricelli's experiment only with water instead of mercury.
If 10 meter long tube or valve from my first suggestion constitute sophisticated equipment is up to you. You also could achieve smaller pressures if you are willing to use liquid with smaller vapor pressures. If it also has greater density than water the length of tube needed would be also smaller.