Spring water doesn't freeze
Quote: IbeatyouracesWater freezes because of the impurities in it.
Did you know that when making drinks say CC and water you should always use FRESH ICE made within the past 24 hrs or so because older ice absorbs the smells tastes of other items in the freezer which change the taste of your drink
The stuff you learn working in a distillery for 15 years
You would think the clean Detroit River would never melt after winter
GO get a gallon of distilled water and a gallon of tap, and let me know if you're right.Quote: IbeatyouracesWater freezes because of the impurities in it.
Quote: IbeatyouracesWater freezes because of the impurities in it.
Lol, what?
Water freezes if it gets to 0 degrees C or colder.
Also, spring water is full of impurities, also known as "minerals."
The more "impure" the water, in general, the slower it freezes, because minerals tend to have salt in them.
You may be thinking of the concept that pure water will not conduct electricity. Only water with impurities will conduct electricity.
Quote: onenickelmiracleSearching into this, I stumbled onto the Mpemba affect where hot water can freeze faster than cold. I never knew that. There was a book written recently about examples of how common sense can fail, but I forgot the title and author. This would probably be in there.
just an FYI, you should never put hot water into a freezer. When you do that it will raise the temperature of the freezer and damage other foods.
Quote: GWAEjust an FYI, you should never put hot water into a freezer. When you do that it will raise the temperature of the freezer and damage other foods.
whether the water is hot or not, you shouldn't put a large quantity of cold water in the freezer either if you don't want all else to undergo thawing, at least to some degree. Water is full of heat* even if the temperature is near freezing to begin with. We had a thread about that.
Spring water is not pure water, it is full of minerals. If it isn't freezing something is wrong with your freezer.
*the bottom line is, heat and temperature are not the same thing, although we tend to think of them as essentially the same thing. They are not.
Quote: onenickelmiracleI put a gallon of spring water in the freezer and after 8 hours it was just barely with a bit of slush.
Eight hours and you expect a gallon to be frozen?
Quote: DJTeddyBearEight hours and you expect a gallon to be frozen?
you might expect more than slush, but it is possible you havent waited long enough, I agree.
It's certainly not the water. A typical functional freezer holds at about 0*F. As salty as the ocean is, it freezes in the high 20's. If your water was so full of salts as to not freeze at 0*F, it would be noticeable. I'd even say it'd be toxic.
Check the temp. Maybe your unit isn't holding temps like it should. Weak compressor, seal leak, could be anything. Just because your food is frozen doesn't mean it's working properly.
Quote: sodawaterWater freezes if it gets to 0 degrees C or colder.
It is my understanding that the cause for the Air France flight off the coast of Brazil was super-cold water that caused the pitot tubes to malfunction. The plane was in a bad storm in cold weather. Since the water was still in the atmosphere it was pure and could attain temperatures below 0C. Somehow, and I forget the details, this super-chilled water caused the pitot tubes to report to the pilots that the plane was going too fast. To correct for this, the pilots eased back on the fuel, causing the plane to go too slow, lose control, and crash.
This is all going off a documentary I saw years ago so I could be getting the details wrong but I'm quite sure water that went below 0C had something to do with it.
Maybe Barb, our aviation expert, can comment.
Quote: FaceA typical functional freezer holds at about 0*F.
How much is that in normal units?
The typical household freezer goes down to -4 C with some being capable of -10 C or so. An industrial meat freezer goes to -15 C. Liquid nitrogen can cool things down to -40 C, which is used for keeping embryos and tissues cold (they don't need to be that cold, but if the power fails then the liquid nitrogen will keep them at a safe temperature for many hours).
-4 C is just a bit under 0 C which is the freezing point of water at sea level. It also keeps ice cream soft and creamy. If your ice cream comes out hard as rock, you need to increase the temps in your freezer.
I believe you are correct in remembering the cause. Water can become super cooled in cumulus clouds and crystallize as ice on aircraft wings, probes etc.Quote: Wizardsuper-cold water
Airspeeds as determined by unobstructed pitot tubes and a pitot tube in an out of the airstream area are never accepted as valid on an airliner but are always compared to each other and to recent values.
The real problem was that the tiny little joystick had no tactile feedback and one pilot was unknowingly pulling the nose up which caused the airspeed to decay, the airflow to become turbulent rather than laminar and the wing to effectively stall so that lift generation went from eighty percent to about thirty percent. This caused stall warnings yet such warnings were misinterpreted. A student pilot should know: you hear the stall warning, you shove the nose down immediately and you add power instantly. Airliner pilots are so removed from such flying techniques that they sometimes forget the basics. Its even easier to forget the basics when you have a little joystick with no "home" position and no tactile feedback of what position it is in. High speed vertical impact is fatal. High speed forward impact is pretty bad, but the airframe is designed to take stress and absorb some damage. The airframe is not designed to withstand a high speed vertical drop. Zero survivability from that.
Any pilot standing on the ground witnessing a plane stall will be 'pushing an imaginary yoke forward to lower the nose" and also will be pushing an imaginary throttle forward to increase the speed. Obviously this poor pilot on the ground will have no effect whatsoever on the distant airplane he is trying to save. When the crew is in the exact same position, that nothing they do will have an effect, that is a Deep Stall wherein the plane's control surfaces (airelons, rudder, stabilizer) are irrevocably stalled so that the pilot aboard the craft can do nothing. This is why wings are designed to stall from the root outward. The root stalls, the pitot tube stalls, the horn goes off, the stick starts shaking .. the stall continues outward and when it finally reaches the airelon, the pilot better have done something and done it pretty darn quick.
Quote: NareedHow much is that in normal units?
;)
It's around -18*C. Your freezer is warm.
Quote: Face;)
Freedom is indivisible.
Quote:It's around -18*C. Your freezer is warm.
I haven't actually measured my freezer. Indirectly I can tell you ice cream comes out rock-hard and needs to be thawed for a few minutes before the scoop can even bite into it.
Quote: NareedQuote: FaceA typical functional freezer holds at about 0*F.
How much is that in normal units?
0° Freedom Units.
Quote: NareedFreedom is indivisible.
I doff my proverbial cap to you. Well played =)
Bottom line, his freezer is borked. There a few things that can affect freezing, but how likely would they be?
Laboratory pure water freezes oddly. I remember seeing it be supercooled once and it was liquid as ever. Then someone hit the container and it flash froze. The chances that both the spring and his container were scientifically pure is zero.
The addition of salts and minerals changes the phase change temps, making the freezing lower and the boiling hotter. But again, to have water so impure as to not freeze at 0*Freedom would be toxic. Noxious. He drank it and didn't immediately gag, so it can't be that.
The only other thing that affects phase change is pressure. But water's properties don't change much despite changes in pressure. The freezing point might lower a little bit, but eventually you'll reach a point where it will skip liquid entirely and just sublimate.
Your freezer is borked. The end =)
Quote: FaceI doff my proverbial cap to you. Well played =)
Thank you. I was inspired.
Quote:Laboratory pure water freezes oddly. I remember seeing it be supercooled once and it was liquid as ever. Then someone hit the container and it flash froze. The chances that both the spring and his container were scientifically pure is zero.
Ah, but the Mythbusters did this already! They got beer, carbonated drinks, non-carbonated drinks and even sports drinks to stay fluid while cooled below freezing. Then they banged each bottle and it flash-froze in a nice cascade of physical reaction.
You can be sure neither the beer not the various drinks were anywhere close to the state of "pure water." You can't be sure how many samples were reuqired for every "successful" test. but the point is it can be done. So it may happen with some random container with some random fluid in some random freezer.
Quote: WizardIt is my understanding that the cause for the Air France flight off the coast of Brazil was super-cold water that caused the pitot tubes to malfunction. The plane was in a bad storm in cold weather. Since the water was still in the atmosphere it was pure and could attain temperatures below 0C. Somehow, and I forget the details, this super-chilled water caused the pitot tubes to report to the pilots that the plane was going too fast. To correct for this, the pilots eased back on the fuel, causing the plane to go too slow, lose control, and crash.
This is all going off a documentary I saw years ago so I could be getting the details wrong but I'm quite sure water that went below 0C had something to do with it.
Maybe Barb, our aviation expert, can comment.
I can make a few comments. The pitot tube works on the Bernoulli principle, where the smaller the tube, the faster the air particles have to rush past the sensor, which measures the density of the particles and translates that into airspeed. It's calibrated for altitude and hooked into that system, since the higher you go, the less air particles there are. Water/ice causing a partial blockage would have given a too-high airspeed reading; a complete blockage would knock the sensors offline the other way. There's always at least 1 in the slipstream, and one passive (protected); for redundancy, the A330 had 2 active and 1 passive on each side. However, only 1 side's sensors are fed into the FDR; they showed an inconsistency that led to their being shut down and the autopilot knocked offline, which is what gave rise to the theory of supercooled water/ice affecting them.
The idea that the pitot tubes were affected by supercooled water partially or fully clogging them is only a theory, but based off of a problem previously identified in that model pitot tube, and unfortunately scheduled for replacement at the company's discretion rather than an immediate need. There had been problems in 8 or so cases with the tube on various Airbus models, and it was seen as acute on other models, but not so much on the A330 used for AF447 here. The important point of this is, there was a known issue with the pitot tubes in storms, the pilots had been trained on it, and they knew they were transitioning an area of storms and turbulence. When the problem arose, however, instead of following their training, they did bizarre and counter-intuitive things, over-reacted to the turbulence in banking, reached the service ceiling of the aircraft in a steep climb, and it simply fell out of the sky tail-first with engines blazing. Full (and overspeed) engine power did nothing for them when the flight surfaces had stopped creating lift, and they were unable (or unwilling) to put the nose down to allow the aircraft to start flying again. The stall warning went off numerous times, yet they appear to have ignored it and its significance.
So, while the pitot tubes led to the problem, it was almost certainly pilot error in not reacting properly to the issue, rather than the pitot tube malfunction bringing the aircraft down. A bootlegged copy of the cockpit voice recorder was released and published but denounced and suppressed by French authorities. A sanitized version was released with the official report, and I don't know whether any of what was censored was pertinent to determining pilot error or distributing it among the 3 pilots; apparently their roles are somewhat aggregated in the report. (US accident reporting does not allow this kind of abbreviated transcript, and CVR's can be quite harrowing to listen to. Apparently France has its own standards.) The pilots' bank, turn, and attitude indicators continued to operate throughout the flight, and yet they somehow allowed the aircraft to climb at a 40 degree rate (normal is 5-15 degrees), which caused the aircraft to slow to only 52 knots with full power (about 60 mph, or about 1/2 the slowest speed it could possibly stay in the air, which would be around 110 knots) when it reached the service ceiling of 38000 feet and began falling backwards. Without the unexpurgated CVR, hard to say what really happened, but those that have heard it think that the pilots were unaware that, with the autopilot off and the aircraft on alternate mode, the normal fail-safes that would not allow the pilots to fly it as badly as they did, were not there to stop them from their errors.
The engines indicated proper operation all the way down, and were briefly commanded back to 50% power twice, but for the most part were at 100% or more. The aircraft hit the water intact, so the wings were not torn off in the turbulence (which is what I thought had happened when I first heard about it), which would at least partially have absolved the pilots. I would guess the inquest and lawsuits are still ongoing.
Quote: FaceI'd say something is afoot. I'd expect it to be frozen as well.
It's certainly not the water. A typical functional freezer holds at about 0*F. As salty as the ocean is, it freezes in the high 20's. If your water was so full of salts as to not freeze at 0*F, it would be noticeable. I'd even say it'd be toxic.
Check the temp. Maybe your unit isn't holding temps like it should. Weak compressor, seal leak, could be anything. Just because your food is frozen doesn't mean it's working properly.
Pure water is the metric standard of temperature... Freezing is 0 boiling is 100. All under controlled conditions. English measure is 32 to 212. Sea water as I recall freezes at 28F or -2C. Again standardized under controlled conditions.
Freezing water (hydrogen bonded materials in general) as a process is a bit tricky. There has to be a "seed" of frozen material that sets off a chain reaction similar to polymerization (formation of plastic from a simpler compound). Super-cooling is cooling below freezing without a seed to initiate the freezing action. This can cause the liquid in question to remain liquid even when "it should freeze". Striking the container is well known to provide such seed-formation. In polymer chemistry such reactions need an "initiator", generally "a pinch" of iron sulfate and a little UV light does the trick.
One's refrig/freezer combo is usually set to 15F: commercial freeze-only (ya know for deer-meat and Costco meat bargains) generally at 0F. At 0F Ice Cream is as hard as a rock, and 15F tolerable. Ice Cream test in order after 8 hours.
Quote: http://en.wikipedia.org/wiki/Properties_of_waterThe melting point of ice is 0 °C (32 °F, 273.15 K) at standard pressure, however, pure liquid water can be supercooled well below that temperature without freezing if the liquid is not mechanically disturbed. It can remain in a fluid state down to its homogeneous nucleation point of approximately 231 K (−42 °C).[27] The melting point of ordinary hexagonal ice falls slightly under moderately high pressures, but as ice transforms into its allotropes (see crystalline states of ice) above 209.9 MPa (2,072 atm), the melting point increases markedly with pressure, i.e., reaching 355 K (82 °C) at 2.216 GPa (21,870 atm) (triple point of Ice VII[28]).
Also, perhaps surprisingly, although air pressure (which is very low at that altitude) has a large effect on the boiling point of water, it has a negligible effect on the freezing point (ie, within 0.01 degree C) http://physics.stackexchange.com/questions/60170/freezing-point-of-water-with-respect-to-pressure
I can suggest a little experiment for those at home.
1. Don't follow the following instructions.
2. Place a gallon of Spring water in the freezer.
3. Before it freezes completely, drink about 30 ounces as fast as you can 30-60 minutes after a fatty meal.
4. Report your results.
Mind you this could be a Canadian experience when you have forgotten your beer in the car during the winter.
Quote: FleaStiffI would think the pilots know what Alternate Law means... the computer is no longer flying the plane, they are. This is so revolutionary and contrary to Autobus normal modes that it would have great impact on them. The crew was fixated on a narrow problem and lost sight of the very basics of flight.
Kind of hard to argue it either way when they're suppressing the full CVR.
However;
The captain had gone for his relief period 5 minutes before the airspeed malfunction.
When he was attempting to return to the cockpit, 5 minutes into the event, the aircraft was at 40 degree pitch and overcorrecting for roll with his 2 co-pilots trying to fix the problem. Like climbing a steep mountain while it's trying to buck you off. I'm guessing by the time he got the (panicking, inexperienced, didn't know the autopilot correction was off) out of the left seat, the aircraft was fatally positioned and there was no saving it. Assuming he ever even got back into the left seat.
Quote: DJTeddyBearEight hours and you expect a gallon to be frozen?Quote: onenickelmiracleI put a gallon of spring water in the freezer and after 8 hours it was just barely with a bit of slush.
This. Very much so.
Disregarding all of the discussion about pitot tubes and aircraft and instead going back to the original question, I have three primary comments.
(1) Do check your freezer with a thermometer. It could be well off the intended set temperature. But I doubt it.
(2) This is a heat transfer problem. The fact that your freezer might provide an ambient temperature of something close to 0°F doesn't mean that the water inside a plastic (I assume) one-gallon jug will drop from room (or outdoor) temperature to lower than 32°F very quickly at all, particularly if the water is not agitated to provide a favorable convective heat transfer coefficient. Now, if you put one of those half-liter water bottles, with the very-thin plastic walls, in your freezer, I expect you would find that it would freeze much more quickly. The heat transfer rate through the thicker plastic walls of the gallon jug, combined with the low convective heat transfer coefficient and the substantial thermal mass of a gallon of water, leads to a very long time required for the water to freeze solid.
In case you are not aware of it, water has one of the highest specific heats of any material you will regularly encounter, meaning it takes a lot of heat removal to cool it to a liquid at 32°F. That is what I expect onenickelmiracle observed. Then, the substantial heat of fusion for water/ice means that a lot more heat must be removed to convert the 32°F liquid to a 32°F solid. If you want the water to freeze quickly, put it in smaller containers with a lot of surface area per unit mass of water and with very thin walls, perhaps sandwich-size, zip-lock bags; i.e., don't insulate the water that you are trying to freeze.
(3) Someone made a comment about hot water taking less time to freeze than cold water. I suspect that is mostly just fiction, but I do know one related topic. Back when we used manually-filled, metal ice trays to make ice cubes (Does anyone here still do that?) and when we had freezers that were not "frost free" (Does anyone have one of those any more?), then there was a common "trick" when people were having parties and the ice was running low. Putting hot water in the ice tray would result in the frost under the tray being melted and a much better heat transfer path being created between the cooling coil in the base of the freezer compartment and the water in the tray. In that situation, it really was possible to wind up freezing what started as hot water faster than if you had filled the trays with cold water and suffered the slow heat transfer rates. An even better solution was to remove the frost from the surface and then insert trays with the cold water.
Quote: DocBack when we used manually-filled, metal ice trays to make ice cubes (Does anyone here still do that?)
Not quite. But at the office we make ice with manually-filled plastic trays.
Quote:and when we had freezers that were not "frost free" (Does anyone have one of those any more?)
Of course not, though I recall them well. Back then I'd say they were even necessary, as the frost could keep things very cold in the face of power failures. Back then we had several power failures per year, in particular during the rainy season. I even kept a candlestick, with a candle, in my room.
The problem with frosty freezers was that the frost just grew without limit. It wasn't unusual to find the usable space reduced to a fraction after a few months. Defrosting the freezer was a common ritual. I recall, too, using an ice-pick to dig out trapped bags of frozen meat.
Quote:An even better solution was to remove the frost from the surface and then insert trays with the cold water.
Did you never just chip off some frost and use it in a drink?
Quote: NareedThe problem with frosty freezers was that the frost just grew without limit. It wasn't unusual to find the usable space reduced to a fraction after a few months. Defrosting the freezer was a common ritual. I recall, too, using an ice-pick to dig out trapped bags of frozen meat.
Did you never just chip off some frost and use it in a drink?
While I've never seen a full-size freezer, in proper working condition, exhibit that, I did take advantage of the frost buildup to store valuables. I don't think anybody would bother searching a TV dinner box in a solid inch of ice...
Never willingly-- that ice tasted horrid.
Even worse, I'm betting the gallon jug was 75% full. It's probably true the fridge isn't working right. The brand was Eureka Springs, spring source Saegertown, PA.
Quote: VenthusNever willingly-- that ice tasted horrid.
I never did, either, but it was well-known as the quick way to get ice in a hurry.
Quote: Doc
(3) Someone made a comment about hot water taking less time to freeze than cold water. I suspect that is mostly just fiction, but I do know one related topic. Back when we used manually-filled, metal ice trays to make ice cubes (Does anyone here still do that?) and when we had freezers that were not "frost free" (Does anyone have one of those any more?), then there was a common "trick" when people were having parties and the ice was running low. Putting hot water in the ice tray would result in the frost under the tray being melted and a much better heat transfer path being created between the cooling coil in the base of the freezer compartment and the water in the tray. In that situation, it really was possible to wind up freezing what started as hot water faster than if you had filled the trays with cold water and suffered the slow heat transfer rates. An even better solution was to remove the frost from the surface and then insert trays with the cold water.
I think the source of the hot water comment is that boiled water freezes faster than water out of the tap because most of the air comes out during the boiling. This is of course true only if it is allowed to first cool to same temperature as the unboiled water. This fact has morphed over time to 'hot water freezes faster than cold water'.
Quote: NareedHow much is that in normal units?
The typical household freezer goes down to -4 C with some being capable of -10 C or so. An industrial meat freezer goes to -15 C. Liquid nitrogen can cool things down to -40 C, which is used for keeping embryos and tissues cold (they don't need to be that cold, but if the power fails then the liquid nitrogen will keep them at a safe temperature for many hours).
-4 C is just a bit under 0 C which is the freezing point of water at sea level. It also keeps ice cream soft and creamy. If your ice cream comes out hard as rock, you need to increase the temps in your freezer.
-4? Where do you live. My freezer's at -18 C or 0 F.
Yeasts can grow at -10 C. You want your ice cream hard as rock.
http://www.fda.gov/Food/ResourcesForYou/Consumers/ucm253954.htm
Quote: DocBack when we used manually-filled, metal ice trays to make ice cubes (Does anyone here still do that?)
until recently we used plastic ice trays. Works pretty well, really. Took about 3 hours to be sure you froze new cubes, something to think about with 8 hours and a gallon.
Quote: Docwhen we had freezers that were not "frost free" (Does anyone have one of those any more?)
I still have an old refrigerator in the garage that is not "frost free". The freezer compartment has no separate outside door, but is contained inside the fridge and seems to just count on isolation of sorts to be colder than the fridge itself. It promises to go forever. One Nickel's unit is of a type and age that suggests it could now be kaput; these new ones are not expected to go much longer. Where's the energy savings in that once you figure in the energy cost of manufacturing?
trivia question:
What was used as coolant in early refrigerators and the big monster ice plant in the middle of every town [most likely] before freon? For extra credit, what was the problem with it?
I didn't look this up. My source is my elders who told me about it.
The internet seems to think you're making the same logically correct thoughts which fail in reality.Quote: kenarmanI think the source of the hot water comment is that boiled water freezes faster than water out of the tap because most of the air comes out during the boiling. This is of course true only if it is allowed to first cool to same temperature as the unboiled water. This fact has morphed over time to 'hot water freezes faster than cold water'.
The hot water is cooled evenly. If you try to freeze cold water, the top of it freezes first (like a lake) which insulates the rest of the water, so it takes longer to freeze. With the hot water, that layer of frost never builds at the top, rather, all the water in the container cools and then freezes semi-evenly.
Unfortunately, the specifics on "how to" do it are a bit of a mystery. I think.
Quote: 98Clubs
Freezing water (hydrogen bonded materials in general) as a process is a bit tricky. There has to be a "seed" of frozen material that sets off a chain reaction similar to polymerization (formation of plastic from a simpler compound). Super-cooling is cooling below freezing without a seed to initiate the freezing action. This can cause the liquid in question to remain liquid even when "it should freeze". Striking the container is well known to provide such seed-formation. In polymer chemistry such reactions need an "initiator", generally "a pinch" of iron sulfate and a little UV light does the trick.
Good post. However, as far as the OP goes, I think the act of drinking / pouring would be enough agitation to set off such a reaction.
I still say this has a very simple explanation. While I consider myself pretty good at sciencing, I would always defer to Doc if he happens to post. The only thing that gives me a tinge of doubt here is my history of freezing stuff. Being a lifelong athlete, I always have a frozen jug. That goes to outdoor games so it melts for drink but is still ice for coldness. I've used 20oz, 3ltrs, gallon milk jugs, just about anything that holds water. 8 hours has always been more than ample.
The only caveat to that is that it's obviously never completely full (I need room to pour the liquid water). On the hottest August day, it's a gallon milk jug 2/3's full. It always froze.
Thanks to Doc, I'll amend my previous declaration - Either your freezer's borked OR we're all overestimating a freezer's power to freeze.
Quote: odiousgambittrivia question:
What was used as coolant in early refrigerators and the big monster ice plant in the middle of every town [most likely] before freon? For extra credit, what was the problem with it?ammonia
That's not just an answer for "back in the day." Commercial refrigeration/freezing/ice-making operations still use that refrigerant. Those are places that don't want their freezer's surfaces at 0°F; they want them at -40°F or so.
Quote: RSIf you try to freeze cold water, the top of it freezes first (like a lake) which insulates the rest of the water, so it takes longer to freeze.
Why would it do that? In the case of a container inside a freezer compartment, the water is going to give up heat through all of its surfaces and will likely start freezing on all of them unless some are significantly better insulated. Build-up of the ice will tend to work its way toward the center. If you did observe an ice build-up on a top/open surface, it would likely be because the ice formed where the container touched a refrigerated surface, broke loose (perhaps just a few crystals at a time), and floated to the surface. That would be the same whether the water started out hot or cold. Besides, as the hot or cold water in a freezer is chilled toward 32°F, natural convection causes gentle circulation, so the temperature is likely rather uniform throughout the liquid. The initially-hot water would always be warmer than the initially-cold water, at least until both reached 32°F and began the phase change.
Now in the case of a lake, the heat extraction is typically almost exclusively to the cold air above, not to the earth below, so it is normal to have the ice form at that surface, not just float to there.
Quote: Doc
Why would it do that? In the case of a container inside a freezer compartment, the water is going to give up heat through all of its surfaces and will likely start freezing on all of them unless some are significantly better insulated. Build-up of the ice will tend to work its way toward the center. If you did observe an ice build-up on a top/open surface, it would likely be because the ice formed where the container touched a refrigerated surface, broke loose (perhaps just a few crystals at a time), and floated to the surface. That would be the same whether the water started out hot or cold. Besides, as the hot or cold water in a freezer is chilled toward 32°F, natural convection causes gentle circulation, so the temperature is likely rather uniform throughout the liquid. The initially-hot water would always be warmer than the initially-cold water, at least until both reached 32°F and began the phase change.
Now in the case of a lake, the heat extraction is typically almost exclusively to the cold air above, not to the earth below, so it is normal to have the ice form at that surface, not just float to there.
I can confirm this. I had a 150gal aquarium in my garage through last winter. As all the sides are exposed, ice grew everywhere. It started on the outside and worked inward. The top, bottom, and sides all grew at the same rate and reached the same thickness.
Quote: FaceI can confirm this.
Thanks for the vote of support. While I may make stuff up in some of the gambling-related threads, here we are talking about a subject in which I have at least a little genuine knowledge. Hey, this is the area that earned me my screen name. ;-)
Quote: boymimbo-4? Where do you live.
I've never measured it. It's what I've read is standard for home freezers.
Quote:Yeasts can grow at -10 C.
I hear yeasts like to surf in liquid helium, too, after a hard day of hiking across the surface of the Sun ;P
Quote:You want your ice cream hard as rock.
No, I want rocks to be hard as rock. Ice cream should be soft and creamy, that's why it's called ice cream.
Quote: DocQuote: odiousgambittrivia question:
What was used as coolant in early refrigerators and the big monster ice plant in the middle of every town [most likely] before freon? For extra credit, what was the problem with it?ammonia
That's not just an answer for "back in the day." Commercial refrigeration/freezing/ice-making operations still use that refrigerant. Those are places that don't want their freezer's surfaces at 0°F; they want them at -40°F or so.
Just caught up with this thread, having forgotten about it. Interesting, didn't know that.
Quote: DocDisregarding all of the discussion about pitot tubes and aircraft and instead going back to the original question, I have three primary comments.
(1) Do check your freezer with a thermometer. It could be well off the intended set temperature. But I doubt it.
(2) This is a heat transfer problem. The fact that your freezer might provide an ambient temperature of something close to 0ðF doesn't mean that the water inside a plastic (I assume) one-gallon jug will drop from room (or outdoor) temperature to lower than 32ðF very quickly at all, particularly if the water is not agitated to provide a favorable convective heat transfer coefficient. Now, if you put one of those half-liter water bottles, with the very-thin plastic walls, in your freezer, I expect you would find that it would freeze much more quickly. The heat transfer rate through the thicker plastic walls of the gallon jug, combined with the low convective heat transfer coefficient and the substantial thermal mass of a gallon of water, leads to a very long time required for the water to freeze solid.
In case you are not aware of it, water has one of the highest specific heats of any material you will regularly encounter, meaning it takes a lot of heat removal to cool it to a liquid at 32ðF. That is what I expect onenickelmiracle observed. Then, the substantial heat of fusion for water/ice means that a lot more heat must be removed to convert the 32ðF liquid to a 32ðF solid. If you want the water to freeze quickly, put it in smaller containers with a lot of surface area per unit mass of water and with very thin walls, perhaps sandwich-size, zip-lock bags; i.e., don't insulate the water that you are trying to freeze.
(3) Someone made a comment about hot water taking less time to freeze than cold water. I suspect that is mostly just fiction, but I do know one related topic. Back when we used manually-filled, metal ice trays to make ice cubes (Does anyone here still do that?) and when we had freezers that were not "frost free" (Does anyone have one of those any more?), then there was a common "trick" when people were having parties and the ice was running low. Putting hot water in the ice tray would result in the frost under the tray being melted and a much better heat transfer path being created between the cooling coil in the base of the freezer compartment and the water in the tray. In that situation, it really was possible to wind up freezing what started as hot water faster than if you had filled the trays with cold water and suffered the slow heat transfer rates. An even better solution was to remove the frost from the surface and then insert trays with the cold water.
1.) 100% correct one should do this.
2.) True. The plastic jug vs. paper carton of milk test.
3.) Semi-fiction. The RATE of cooling hot to cold is greater than cold to colder.
Addendum: Remember the OLD refidgerators that you had to periodically thaw? There was/is a reason for that. Ice is a very good thermal insulator. The freezing tubes coated with ice are VERY inefficient, inflating the electric bill markedly, shrinking the freezer volume a bit, and causing a "warm" freezer. BTW, Ice formed due to the Humidity within the freezer water vapor/moist humid air is bad for refridgerators and freezers.
Quote: 98ClubsBTW, Ice formed due to the Humidity within the freezer water vapor/moist humid air is bad for refridgerators and freezers.
Air carries some moisture with it at all times, even in a dry place like the Sahara desert. Modern freezers draw the moisture out of the air so it won't condense and freeze insisde. It's really that simple.
Frost inside a modern freezer is an indicator that the door is not airtight. If there is some constant inflow of new air, the mechanism can't remove all the moisture and some frost will form.
