# Help Me Calculate The Temperature For A 5-Gallon/19-Liter Jug Of Water To Freeze Solid In 12 Hours **URL:** \ **Category:** Factual Questions\ **Created:** [October 18, 2019, 4:38pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962 "2019-10-18T16:38:11Z")\ **Posts on this page:** 17\ **Page:** 1
**Author:** ![HeyHomie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/heyhomie/32/207_2.png) [@HeyHomie](https://boards.straightdope.com/u/HeyHomie)\ **Post date:** [October 18, 2019, 4:38pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/1 "2019-10-18T16:38:11Z")
My tap water is disgusting, so I buy [my water](https://www.primowater.com/) via these 5-gallon (19-liter) refillable jugs. I don’t always bring them inside right away, because they’re heavy and I’m a pussy, and so they’ll oft sit in the back of my car until I need them. In the winter, this stresses Mrs. Homie out, who insists that they’ll freeze solid if the temperature drops below 32F/0C and stays there overnight. I know she’s wrong, but I don’t know _how_ wrong. By my estimation, 12 hours at or just below freezing means, at most, a thin layer of ice on the surface. But how long to freeze solid in, say, a 12-hour period? My WAG is that for a 5-gallon/19-liter jug of water to freeze solid in 12 hours, the temperature would have to be in the neighborhood of -20F (-28C) for that period of time. But I could be way off. Any thoughts? ---
**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\ **Post date:** [October 18, 2019, 4:45pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/2 "2019-10-18T16:45:14Z")
[\*\*Check this out. \*\*](https://www.quora.com/How-long-does-it-take-water-to-freeze) ---
**Author:** ![HeyHomie](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/heyhomie/32/207_2.png) [@HeyHomie](https://boards.straightdope.com/u/HeyHomie)\ **Post date:** [October 18, 2019, 4:48pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/3 "2019-10-18T16:48:46Z")
> [@Jasmine](#): > > [\*\*Check this out. \*\*](https://www.quora.com/How-long-does-it-take-water-to-freeze) That article might as well have been written in Japanese. All of that algebra for a man who can barely do simple arithmetic. Please. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [October 18, 2019, 5:13pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/4 "2019-10-18T17:13:31Z")
They used to drop water bottles off at my house and leave them on the front porch if no one was home. I didn’t keep track of the temperatures but between 18 and 24 hours, at maybe an average of 27F, they didn’t freeze. Those bottles are supposed to be able survive freezing without breaking anyway, if it did freeze you’d just have to wait a little while after you carry it inside. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [October 18, 2019, 6:21pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/5 "2019-10-18T18:21:06Z")
> [@Jasmine](#): > > [\*\*Check this out. \*\*](https://www.quora.com/How-long-does-it-take-water-to-freeze) With due respect, That equation is wrong. The author is confused between heat transfer coefficients and specific heat. ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [October 18, 2019, 6:50pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/6 "2019-10-18T18:50:41Z")
To even begin working this out, you’d need the starting temperature of the water and probably some insulation characteristic values for the jug. ---
**Author:** ![Tim\_R.Mortiss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tim_r.mortiss/32/142_2.png) [@Tim\_R.Mortiss](https://boards.straightdope.com/u/Tim_R.Mortiss)\ **Post date:** [October 18, 2019, 7:32pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/7 "2019-10-18T19:32:01Z")
This sounds like a good opportunity for the old adage: “One experiment is worth a thousand expert opinions.” ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [October 18, 2019, 7:39pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/8 "2019-10-18T19:39:38Z")
And insulation characteristics of the car, too. And I agree with **Tim R. Mortiss** : The easiest way to find all of the relevant values would be just to run the experiment anyway. ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [October 18, 2019, 9:08pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/9 "2019-10-18T21:08:16Z")
Do you have room in your freezer for one of the jugs? If so, put one in there for 12 hours, then show it to her. It should still be liquid enough to use as a cool pillow while you sleep on the couch. ---
**Author:** ![icbm](https://avatars.discourse-cdn.com/v4/letter/i/2acd7d/32.png) [@icbm](https://boards.straightdope.com/u/icbm)\ **Post date:** [October 19, 2019, 2:45pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/10 "2019-10-19T14:45:15Z")
Would the experiment scale up? If OP put 9.5 litres into a jug so that the freeze expansion has lots of room to not burst the jug or overflow into the trunk. Leave it until it freezes, then multiply the time elapsed by 2? ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [October 19, 2019, 2:47pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/11 "2019-10-19T14:47:44Z")
> [@icbm](#): > > Would the experiment scale up? If OP put 9.5 litres into a jug so that the freeze expansion has lots of room to not burst the jug or overflow into the trunk. Leave it until it freezes, then multiply the time elapsed by 2? Doesn’t work. The surface area of the container doesn’t scale linearly. ---
**Author:** ![Frankenstein\_Monster](https://avatars.discourse-cdn.com/v4/letter/f/ccd318/32.png) [@Frankenstein\_Monster](https://boards.straightdope.com/u/Frankenstein_Monster)\ **Post date:** [October 19, 2019, 10:27pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/12 "2019-10-19T22:27:20Z")
It takes 6,7 Megajoules of energy to freeze 20 liters of water. That means it would take 24 hours to freeze if the cooling power were 75 Watts. What kind of cooling power do we get with a 20 liter PET bottle sitting out in a few K of freezing temperature? Is it more or less than 75 Watts? Here is a study on the heat transfer characteristics of PET bottles: [Study on heat transfer coefficients during cooling of PET bottles for food beverages (PDF)](https://www.researchgate.net/publication/282841499_Study_on_heat_transfer_coefficients_during_cooling_of_PET_bottles_for_food_beverages) Fluid dynamics is a huge factor in the cooing time. Can anybody tell from that PDF if the power is easily more than 75 Watts or definitely less? With a quick glance I think it’s more. So I think the bottle will EASILY freeze in much less than 24 hours. but maybe someone can read that article more thoroughly and/or has other sources. ---
**Author:** ![Frankenstein\_Monster](https://avatars.discourse-cdn.com/v4/letter/f/ccd318/32.png) [@Frankenstein\_Monster](https://boards.straightdope.com/u/Frankenstein_Monster)\ **Post date:** [October 19, 2019, 10:43pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/13 "2019-10-19T22:43:06Z")
> [@](#): > > As expected, air cooling was extremely slow (Ug ~ 10 W/m2 K) but increased 1.5 times in dynamic conditions. And I realized the surface area of a 20 liter bottle is less than half a square meter. With five degrees Celsius below zero, 15 W/m2\*K and 0.5m2 the power would be half of 75 watts or the freezing time would be 48 hours. With twenty Celsius below zero the freezing time would be 12 hours. I think. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [October 20, 2019, 3:39am UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/14 "2019-10-20T03:39:13Z")
With no wind blowing 2 to 4 W/m2-K is the typical overall heat transfer coefficient. However, there is heat conduction from the bottom of the bottle which is probably resting on a cold surface. ---
**Author:** ![EdelweissPirate](https://avatars.discourse-cdn.com/v4/letter/e/8491ac/32.png) [@EdelweissPirate](https://boards.straightdope.com/u/EdelweissPirate)\ **Post date:** [October 20, 2019, 4:56am UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/15 "2019-10-20T04:56:50Z")
> [@am77494](#): > > With due respect, That equation is wrong. The author is confused between heat transfer coefficients and specific heat. You’re absolutely right. Also, the author uses “such” in an egregiously affected manner. Oof. ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [October 20, 2019, 1:16pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/16 "2019-10-20T13:16:12Z")
> [@TriPolar](#): > > Those bottles are supposed to be able survive freezing without breaking anyway, if it did freeze you’d just have to wait a little while after you carry it inside. If the container is sealed, the expansion of the water as it freezes can be enough to split it open. The worst-case scenario is that the bottle freezes, splits, and then thaws and leaks out all over the car floor through the new hole in the bottle. Since liquid water takes up about 90% of the volume of the same amount of frozen water, the solution is to fill your bottles less than 90% full just to be on the safe side. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [October 20, 2019, 1:24pm UTC](https://boards.straightdope.com/t/help-me-calculate-the-temperature-for-a-5-gallon-19-liter-jug-of-water-to-freeze-solid-in-12-hours/841962/17 "2019-10-20T13:24:20Z")
> [@MikeS](#): > > If the container is sealed, the expansion of the water as it freezes can be enough to split it open. The worst-case scenario is that the bottle freezes, splits, and then thaws and leaks out all over the car floor through the new hole in the bottle. > > Since liquid water takes up about 90% of the volume of the same amount of frozen water, the solution is to fill your bottles less than 90% full just to be on the safe side. I don’t know if the OP is filling his own bottles, that can be done at some places. The ones filled at the factory look like they have enough space for expansion if they freeze. Most bottled liquids are that way to prevent freezing in storage and shipment.