|If you let your air out in space will there be a
pocket of air in space?|
|Question Date: 2014-04-25|
The air will actually keep spreading out until
it's like it's barely there at all. It will be
the same number of gas molecules as before, but
instead of being spread evenly over, say, a few
thousand gallon volume of a spaceship they will be
spread over trillions of gallons (actually much
more than trillions, but you get the point).
A gas that isn't frozen solid or cooled to
liquid temperatures will try to fill the entire
volume of the container it's in, and out space has
a huge volume. This happens because in gas form
the various air molecules are all constantly
moving and bumping into each other, so as they
move they will spread out, because even if
initially even if they were all moving in the same
direction, eventually they would jostle each other
and their motion would become random and they
would travel in all sorts of directions.
At normal air pressure on Earth's surface we
have 2.7*1022 gas molecules per liter
of air (In chemistry in high school you'll learn
that this is 1 mole of gas per 22.4 liters). We
can have that density of air because gravity holds
the atmosphere close to Earth and prevents the air
from spreading out. This is why small planets
don't have atmospheres, they don't have enough
gravity to hold their atmosphere and eventually it
all just flies away.
If you were in outer space and you exhaled, it
would locally create an area with more air.
However, because there are so few molecules
everywhere else, this pocket of air will rapidly
expand. You can think of it like the universe
diluting your air. Because the pressure is so low
in outer space (there are so few molecules close
together), the expansion of this air is pretty
violent, so you wouldn't have a pocket of air like
you might see if you were to breathe into a jar
underwater or something similar.
Space is a vacuum, which means a volume devoid of
matter (without any molecules/atoms). However, it
is not a perfect vacuum, there are a few (less
than 100) molecules or atoms / cubic meter. This
is roughly about
10,000,000,000,000,000,000,000,000 times less
dense than air.
If you were to release air into this vacuum, it
would very quickly diffuse outwards- forever. Soon
the air molecules, mostly nitrogen and oxygen,
would have spread out so much (because outer space
is so big), that you wouldn't notice them, and the
pressure would not change.
No, there will not be a pocket of air in space.
Gases (like air) expand to fill their containers,
and in space there is no container, so it would
simply expand until it is the same density as
1. Interesting question! When you release some
air into the vacuum of space, there will initially
be a pocket of air. However, because of the
natural tendency of molecules to diffuse, or go
from a place of high pressure to low pressure
(think about it like a bunch of balls on top of a
hill; they want to roll downhill), the pocket of
air will quickly expand. After a short amount of
time the air will have expanded so much that the
pressure can basically be considered to have
returned to the original amount in the space
(since there is so much emptiness).
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