This question came to me in a discussion (with a flat Earther, don’t ask). If you put a beaker of water into a sealed chamber and suck out the air, then the water will boil once the air pressure drops below the vapour pressure of the water (about 0.35psi at 20 degrees C).
Would the water boil more easily if you ran the same experiment but in zero gravity? It seems like the Earth’s gravity should be supplying an additional downward force on molecules trying to escape the beaker (which they can only do in an upward direction), but I suspect the effect would not be measurable.
Gravity doesn’t enter into the equation/mechanisms of boiling at all. It would change the situation in that, instead of staying put in the bottom of the pot, the liquid would form a sphere and thus you’d have to heat it in a different way - but an old fashioned heating resistance in a steel sleeve works the same to heat up water in a cup or in a floating sphere.
I think we could measure the effect with the most sophisticated and precise measuring equipment … barely … the electro-magnetic forces dispersing the vapor molecules is much much much higher than the gravity on such a small mass …
Said Flat Earther then says, well if gravity can’t affect the water vapour molecules from boiling off, how can it stop the atmosphere from boiling off into space. I treied to make the point that the atmosphere has already “boiled”, which is why it is not liquid. That doesn’t mean it escapes into space.
Gravity puts a minimum velocity that would allow the molecule to escape to infinity. Removing that minimum would simply allow the dispersion of the material to extend to forever.
Since your hypothetical involves a closed system, escape velocity isn’t really all that important.
Well … that’s a big challenge for sure … explaining to a Flat-Earther the simplest concepts of Physics …
Of course gravity has a profound effect on water molecules boiling off … remember, here we’re measuring the force of gravity in terms of pressure … now we’ve reduced our pressure, which means we’ve reduced the force of gravity … we won’t have the weight of the 200 mile thick air column holding these molecule in their liquid state … I’m assuming your pressure chamber is something that fits on your kitchen counter …
Actually the atmosphere is boiling off into space, just at the exact same rate as material in space is being captured by the atmosphere … it’s in an equilibrium state … mass out = mass in … ignoring several other processes going on …
If we treat the atmosphere as individual particles, we can assign a force vector to each one … if we treat the atmosphere as a fluid continuum, then we can combine all the individual force vectors into a single value called pressure …