What are those tiny bubbles that form on the sides of a glass of water that's left beside your bed overnight?

August 17, 2004 12:38 PM

What are those tiny bubbles that form on the sides of a glass of water that's left beside your bed overnight?
posted by Keith Talent to Science & Nature (19 answers total)

The accumulated gases produced by bacterium during their various metabolic processes.
posted by ChasFile at 12:45 PM on August 17, 2004

or dissolved air that is no longer dissolved in the water.
posted by sauril at 12:54 PM on August 17, 2004

What sauril said--no bacteria necessary. Especially if it was a glass of cold water which warms up to room temperature overnight--most gases are more soluble in colder water than warmer.
posted by DevilsAdvocate at 1:15 PM on August 17, 2004

Response by poster: "or dissolved air that is no longer dissolved in the water."

This makes sense. When the water comes out of the tap, it is cold. Cold water holds more dissolved oxygen than warm water, the water warms over the course of the night, and releases oxygen it can no longer keep in solution.

I'm kinda skeptical of the whole bacteria/metabolic process thing. Mostly because it seems unlikely that the byproduct of bacteria has literally a billion times the volume of the bacteria themselves.
posted by Keith Talent at 1:15 PM on August 17, 2004

I would agree the bubbles are likely due to temp changes during the night.
posted by mathowie at 1:23 PM on August 17, 2004

Not just oxygen, but pretty most atmospheric gases. Nitrogen is going to be very important too.

The water is probably mostly air-saturated by the aerator in your tap, so there's lots of gas to release.
posted by bonehead at 1:37 PM on August 17, 2004

ChasFile, what was that? A guess? If so, it was pretty authoritatively stated. Pulling stuff out of your ass is fine (yes, tagline) but please label it accordingly.
posted by stupidsexyFlanders at 1:54 PM on August 17, 2004

A guess: chlorine gas coming out of your city's treated water? It's my understanding that it will do this naturally if you give it time, so you don't need to purchase a filter if that's all you want.

Obviously this guess is wrong if you're using bottled water.
posted by pmurray63 at 2:16 PM on August 17, 2004

I believe a lot of it is carbon dioxide that was absorbed into the water over time becoming unabsorbed. I kind of remember reading that this is what can make old water unpleasant to drink (carbon dioxide + water = weak carbolic acid?)
posted by RustyBrooks at 3:02 PM on August 17, 2004

Response by poster: CO2+H2O=Soda, no?
posted by Keith Talent at 3:22 PM on August 17, 2004

Not carbon dioxide or any other exotica.

It's just ordinary atmospheric gas, for the cold/warm water reasons listed above.
posted by five fresh fish at 3:33 PM on August 17, 2004

Er, not strictly CO2 or other exotica. It'll be all sorts of ordinary elements of our atmosphere.
posted by five fresh fish at 3:33 PM on August 17, 2004

CO₂H₂O definately doesn't give soda, soda consists of oxidised sodium (Na).

CO₂H₂O <-> H₂CO₃ (carbonic acid).
posted by fvw at 4:21 PM on August 17, 2004

ehm, CO₂ + H₂O...
posted by fvw at 4:22 PM on August 17, 2004

Boiled water doesn't get the bubbles if you leave it overnight.
posted by i_cola at 4:49 PM on August 17, 2004

That is because the gas is already gone.
posted by kenko at 5:27 PM on August 17, 2004

Related question: Is that why hot water is often cloudy/filled with tiny bubbles when it comes out of the tap?
posted by armchairsocialist at 6:01 PM on August 17, 2004

Also, one of the reasons the gas sticks to the cup because there are tiny little bumps inside the glass, and the gas bubbles grab onto the bumps so they stick there.
posted by jmd82 at 7:52 PM on August 17, 2004

Makes sense, acsocialist. Hot water tank is under pressure (water supply pressure, ~30lbs?) and the incoming water is cold. Heated up, the pressure prevents the gas from coming out, ergo it comes out when it hits atmospheric pressure.
posted by five fresh fish at 8:46 PM on August 17, 2004