freezing water

last night i mistakenly left a bottle of water in my car. when i got in my car this morning after a well below freezing night the bottle was not frozen at all the water was still liquid (though the air in the bottle shrank like a balloon in the freezer). i didnt think much of it until i started driving and i turned on the heat. about five minutes later i went to take a drink from the bottle and noticed the water was almost completely frozen. why di this happen?

Originally posted by yelrambob
last night i mistakenly left a bottle of water in my car. when i got in my car this morning after a well below freezing night the bottle was not frozen at all the water was still liquid (though the air in the bottle shrank like a balloon in the freezer). i didnt think much of it until i started driving amd i turned on the heat. about five minutes later i w ...[text shortened]... a drink from the bottle and noticed the water was almost completely frozen. why di this happen?

Your heater didn't work and was blowing freezing cold air. Case Closed!

F. Granny.

Originally posted by smw6869
Your heater didn't work and was blowing freezing cold air. Case Closed!

F. Granny.

true i was blowing super freezing air but besides the fact that im mr freeze as famous from such marvel comics as batman this has also happened (or something similar to) two different people i know

Assuming it wasn't like -30 degrees in the car, and that that the bottle was full, this is because there was not enough energy to get the water to go through a phase change, solid to liquid. It was probably 0 degrees and maybe partially frozen. If it was very very frigid, it's possible that the water would have frozen.

The air condensed because it cooled. The molecules lost KE, so moved slower. They contracted.

Originally posted by yelrambob
last night i mistakenly left a bottle of water in my car. when i got in my car this morning after a well below freezing night the bottle was not frozen at all the water was still liquid (though the air in the bottle shrank like a balloon in the freezer). i didnt think much of it until i started driving and i turned on the heat. about five minutes later i w ...[text shortened]... a drink from the bottle and noticed the water was almost completely frozen. why di this happen?

It's possible, though unlikely, that the sudden expansion of the moist air in the bottle caused enough of a temperature drop to freeze the water. Of course, this is only plausible with a rapid expansion and a small amount of water.

Another unlikely answer could be that if the water were very pure, it could theoretically become supercooled (i.e. the water could be colder than the freezing temperature, but remain in a liquid state because of a lack of nucleation sites for crystallization). Any jostling, like an expansion of the bottle, would jostle the liquid creating bubbles and nucleation sites, turning the whole aliquot to ice. Of course, supercooling is difficult to achieve and it would be an extraordinary coincidence if this happened to more than one person you know.

The most likely answer was that the water was well on its way to freezing, and because you were driving you didn't notice the freezing process, only the final change.

Other than those, I'm stumped. 😕

Originally posted by Ramned
Assuming it wasn't like -30 degrees in the car, and that that the bottle was full, this is because there was not enough energy to get the water to go through a phase change, solid to liquid. It was probably 0 degrees and maybe partially frozen. If it was very very frigid, it's possible that the water would have frozen.

The air condensed because it cooled. The molecules lost KE, so moved slower. They contracted.

yes i understand the contracting air i just forgot the word for it kinetic energy and all. but the water i assure you was wholly liquid and its 18 degrees farenheight now and it was colder last night. (also the bottle had been opened and was not entirely full)

i just thought there may have been some scientific reason that when the air around the bottle warmed it spontaneously froze(thats what happened in the other cases i mentioned)

EITHER decreased temperatures OR increased pressure will freeze water. The hot air might heat the air inside the bottle, making it expand and adding to the pressure on the water, which could crush it into the solid state.

Originally posted by AThousandYoung
EITHER decreased temperatures OR increased pressure will freeze water. The hot air might heat the air inside the bottle, making it expand and adding to the pressure on the water, which could crush it into the solid state.

But the air was compressed to begin with. Why would it expand to more pressure then before the cooling?

I'm assuming the airco wasn't set to 40 C but a normal temperature, comparable to the temperature before the night out.

Originally posted by yelrambob
true i was blowing super freezing air but besides the fact that im mr freeze as famous from such marvel comics as batman this has also happened (or something similar to) two different people i know

Batman is a DC comic

Ok, so it froze when you opened it / driving.

You turned the heat on, so the air outside is at a much greater heat. Therefore, when you opened the bottle, the hot outside air exerted much more pressure on the water than the water exerted on the air. Thus, the air did considerable work on the water, which caused the water's volume to decrease rather fast, contracting the molecules to a solid state.

Originally posted by TheMaster37
But the air was compressed to begin with. Why would it expand to more pressure then before the cooling?

I'm assuming the airco wasn't set to 40 C but a normal temperature, comparable to the temperature before the night out.

But the air was compressed to begin with. Why would it expand to more pressure then before the cooling?

Because the bottle might not want to reshape itself to the original high volume state. It might get stuck in a crushed shape, limiting volume.

Did the freezing happen after the cap was removed or while it was still screwed on?

I found a bunch of videos on Youtube having to do with supercooled water in plastic bottles quickly turning to ice ("instant ice" ), so apparently it's not as uncommon as I thought. This is almost definitely what happened.

Here are some quick calculations to show why the expansion of the moist air wouldn't freeze the ice. The work done by a gas expanding at constant temperature is given by:

Q = n * R * T * ln(V2/V1)

I'm assuming the bottle was of drinkable size, about 500 mL, and that it was half full of water. I'll also assume that the top half of the bottle was crushed to about 1/3 of its normal size. I'll use the ideal gas law to find the number of moles of air in the bottle at standard pressure and 265 K (18 F):

n = PV/RT = (101325 Pa) * (0.5 L * 1/3 * 1 m3/1000 L) / (8.314 J/mol*K) * (265 K)
= 0.0077 mol

So the heat absorbed in the expansion is therefore:

Q = (0.0077 mol) * (8.314 J/mol*K) * (265 K) * ln (0.5 L/ 0.5 L * 1/3)
= 18.6
= 20 J

I've assumed the bottle is half full, so it contains 0.250 kg of water. Considering the specific latent heat of fusion for water is about 334 kJ/kg at 0 C, or 334 kJ/kg * 0.250 kg = 83.5 kJ = 83,500 J for the aliquot, the expansion of the moist air in the bottle wouldn't be enough to freeze even a small portion of the water.

If the bottle was half empty and the top portion crushed then when you were driving around the water would have sloshed around inside the bottle and uncrushed the bottle back to its original shape.

This would have lowered the pressure inside the bottle which in turn would lower the temperature of the gas inside the bottle, thus cooling the water to a point where it froze.

Originally posted by andomasahashi
Batman is a DC comic

ugh i knew somthing was wrong with that

Originally posted by AThousandYoung
[b]But the air was compressed to begin with. Why would it expand to more pressure then before the cooling?

Because the bottle might not want to reshape itself to the original high volume state. It might get stuck in a crushed shape, limiting volume.

Did the freezing happen after the cap was removed or while it was still screwed on?[/b]

yeah the cap was still on