keyshawn

Last night, I left two bottled waters in my car overnight, in the garage. Mind you, since I'm a clevelander [experiencing temps in single digits, Fahrenheit], the water froze, only some of it.

There were two bottled waters, both from the same manufacteur and same size, one was already about 1/4 empty and the other, was still completely full and had not been opened yet. The one that had already been opened was completely frozen. However, the one that had not been opened yet, the water inside still was not frozen.....

I'm a bit bewildered why....I would think that temperature would be able to permeate through the plastic to freeze the water inside, even if it were not open yet.

Keyshawn.








PS - I just realized - 'bottled water' and 'water bottle' mean two different things, must be hell for those trying to pick up english

__________________
currently reading:

currently playing :

the_marq

Is it possible that the bottle that had not been opened yet was under pressure? That may have contributed to it not freezing.

Also, were the bottles right next to each other, certain parts of your car and/or garage may be warmer than others.

__________________
The Truth:

Johnny Cash could have kicked Bruce Lee's ass if he wanted to.

#3 in a series

keyshawn

The bottles were right next to each other.

__________________
currently reading:

currently playing :

CSflim

Was it carbonated water or still?

If it was carbonated, it means the inside of the bottle would be under pressure (I think). Water under pressure is more difficult to freeze, so that would explain it.
(Don't forget, water expands when frozen).

If it was still water...than maybe it was still somewhat more pressurised than the other due to being unopened?

__________________

frogza

Compression can cause a slight raise in temperature, and I mean slight. Perhaps the one that wasn't opened didn't freeze because as the water cooled and began to freeze, it expanded, causing a small degree of compression. The slight raise in temperature inside the bottle may been just enough to keep all of its contents from freezing. Outside conditions would have to be perfect for this to happen, i.e. the outside temperature just low enough to freeze it but not so low that it would overpower the slight rise in temp inside the bottle. So I wouldn't expect it to happen very often.
The open bottle would have had more room to expand, so it wouldn't have had any compression.

supersix2

The reason is actually quite simple. The amount of heat required for something to change phases i.e. liquid to gas or liquid to solid depends on a property of the matter called specific heat and its mass.

Note that heat is not actually how hot or cold something is but the actual energy of something so when I say the heat required for something to change phases it can either mean a gain or loss of heat. In the case of freezing water we will be talking about a loss of heat.

Now onto the equation:
Q = cmdT
Q is the variable for heat measured in joules
c is the variable for specific heat measured in joules/gram
m is the variable for mass measured in grams
dT is the quantity of the change in temperature

This particular equation does not actually represent the amount of heat needed for matter to change phases. To find that we use another equation and a property called either the Latent Heat of Fusion (liquid changing into water or vice versa) and the Latent Heat of Vaporization (liquid into gas or vice versa). That equation as well depends on the mass of the matter and I can't remember it off the top of my head and my physics book is not handy but its bascially along the same lines as Q = cmdT except it has a new property called the heat of fusion factored in. The basic idea you need to know is that the amount of heat required depends upon its mass.

As you can see the amount of heat needed to for something to change phases is directly proportional to its mass. Therefore if you have more some something, in the case a more water in a bottle, it will require a different amount of heat to change phases.

In other words, the more water you have, the more energy it will need to lose in order to freeze.

CSflim

Duh! I'm an idiot. How did I fail to notice keyshawn said one of the bottles was 1/4 empty. I was thinking of them both being full, with one having been opened.

__________________

supersix2

To those who thought that the pressure of an unsealed bottle would result in the water not freezing I would like to offer this explanation.

It is true that pressure has a great deal of an impact on what phase matter is in. Extremely low pressure causes liquids to boil rapidly with almost no change in temperature at all. Extreme high pressure can force gases to become liquids like the liquid hydrogen and liquid oxygen used for rocket fuel. Cooking instructions will tell you lower temperatures for boiling water if you are at higher altitudes.

However all of these examples I listed are results of extreme pressure changes. The pressure inside of one of those water bottles would not have that noticable an effect on whether the water would freeze or not.

Also, a bottle of water is a fairly expandable container so any pressure "built up" as a result of the ice expanding and causing an increase in the pressure of the fluids in the bottle can be released by the expansion of that bottle.

frogza

Thanks for the explanation *feeling rather sheepish*

keyshawn

Thank you for the info, especially supersix2

__________________
currently reading:

currently playing :

Rangsk

It's always good to think of things in extremes just to prove to yourself that something make sense.

What takes longer to freeze in your freezer? A drop of water or a bucket of water? There's your answer.

__________________
"Don't believe everything you read on the internet. Except this. Well, including this, I suppose." -- Douglas Adams

Pip

But the 1/4 bottle was completely frozen while the unopened one was still completely liquid, so I don't think that could be it. I've seen the same thing happen with soda bottles left out in a truck overnight, if there was one that had been opened, no matter how much or little there was in it, they'd be frozen, but the unopened ones still looked okay. Until you opened them, that is, then they'd turn into instant slush. My ChemE friends would say this was because the soda had been 'under-cooled' (not sure of the english term) so that the fluid temperature was below freezing, and when the bubbles started stirring the fluid that triggered the freezing process. Kind of like when you have under-cooled rain, when it hits the ground it instantly turns to ice.

C4 Diesel

I was a ChemE undergrad... Under-cooling with any sort of stability generally only occurs with very slight drops below the freezing temperature and the medium must be totally unagitated. Otherwise the cooling must occur very quickly which was not the case. Also, this is probably not the phenomena that would be observed in the case of a carbonated beverage. What would more likely be happening is that the one that was opened was largely decarbonated. Since water (and most liquids) decrese in freezing temperature and increase in boiling point when there is dissolved solute (which is why we put ice on sidewalks), it is actually the dissolved carbon dioxide that would really be causing the other not to freeze, which also can explain why it instantly flurries with ice upon opening.

Don't underestimate the low thermal conductivity of a plastic bottle. Especially since the other one was open. The cold air can get in the open bottle, cool off and freeze the water which in turn heats the air, which rises and escapes the bottle, allowing cooler air to again touch the surface. This movement of heat caused by a flow of molecules (convection) is generally faster than heat transfer by collisions between molecules (conduction). The exception would be convection with a highly insulating material or conduction with a superconductor, and neither of these are part of the scenario.

__________________
C4 to your door, no beef no more...

pig

Two points :

1. supersix2 is exactly correct, and in addition:

2. due to the smaller volume of liquid in the opened bottle, the temperature gradient is more extreme within the liquid. thus, less time is required to lower the temperature of the smaller volume of liquid, and phase change occurs more rapidly.

__________________
You don't love me, you just love my piggy style

C4 Diesel

It would be an issue of thermal mass, not temperature gradient. Assuming the bottle is a tall cylinder, even if they were both closed, the temperature gradients would be very similar. This is because the smaller dimension is the radius, not the height, and since decreasing the amount of water in the bottle does not affect the radius and only affects the height (assuming it was standing relatively upright), the direction containing the more drastic temperature gradient would not change. The bottle would only cool faster because there is actually less to cool.

The temperature gradients would look something like this... Imagine taking a rainbow and shaping it into a two-dimentional rectangle (with the longer dimension being height, such that it somewhat resembles a vertical bottle) with rounded corners. The colors would represent the temperature profile. The full bottle would be that rainbow, the other would be one that was 1/4 shorter.

__________________
C4 to your door, no beef no more...

Pip

I sincerely hope keyshawn didn't leave an open water bottle in his car, but rather an opened. In the summer we sometimes put plastic soda bottles in the fridge (about 5 °F I think) to cool them down fast, if you leave them for more than an hour they'll be frozen solid. The stuff about the dissolved carbon dioxide sounds reasonable though. Maybe that was it?

pig

C4 - lacking sufficient information about the position of the bottles, etc - I honestly can not make a better statment about this portion, save what I'll say below.

I believe I understand your analogy, and thus I have this question: if you have a rectangular rainbow that is x units long, and another rectangular rainbow which is x/4 units long, with the same "non-dimensionalized" spectrum across them, I do not understand how this would not affect the color gradient, as I would think it would have to be "compressed" on the shorter rectangular rainbow. Would that compression not essentially represent a more severe temperature gradient, in the longitudinal direction? I wholeheartedly agree with your radial statements.

While I appreciate the thermal conductivity of plastic, I am guessing that the air in a plastic bottle with a thickness of ~ 1/16 " or less will reach thermal equilibrium with the air on the outside of the bottle if left overnight. I have never conducted the experiment, nor have I performed the calculations, thus I can not state as fact. I do think that a zero-flux gradient at the center of your radial coordinate system and a low-temperature temperature condition on the edge of the circle is less severe than two low-temperature conditions on the end of the longitudinal axis. Of course, there will result a zero-flux condition in the middle of the cylinder as well; either way I agree that the volume (which I believe is related to the thermal mass?) differences will directly affect the rate of cooling and phase change.

__________________
You don't love me, you just love my piggy style

keyshawn

It was only <i> Opened. </i>

Also, NOTE: If it does make a difference [according to C4 Diesel, it may] BOTH of the bottles were tilted at about a 15 degree angle..

__________________
currently reading:

currently playing :

AquaFox

lol, frozen water is great, i pulled out afew frozen bottles from my car the other week, i cut the bottles open to get the ice out, and the ice from the one bottle was shaped like a big condom, even with the resvoir tip



but someone took my ice out of the freezer....

__________________


...AquaFox...

supersix2

Look, it doesn't matter where the bottles were in the car, what angle they were at, whether one was open or not, or the conductivity of the plastic. All that matters is the amount of water being frozen.

The equation clearly states that as well as common sense should. As someone above said, "what takes longer to freeze a drop of water or a glass of water." Also think of it this way...

I have a hot frying pan on the stove. I have a cup of water and I drip some of the water on the hot frying pan, the water drops instantly boil and evaporate. Now i dump the whole cup of water on the frying pan. What happens now? The water hits the frying pan and sizzles but not all of it is boiled off. Why? Because the frying pan does not have enough heat to energize all of that water into vapor. You can perform both the freezing and the boiling experiments yourself.

Pip

And look, what you are talking about are volumes hundreds of times as large as the other, but in this case one was just ~1.3 times as large as the other, which is pretty much no difference at all when we talk about a timespan of several hours. No, I'm guessing the diffused carbon monoxide in the unopened one lowered the freezing temperature just enough so that it wouldn't freeze, like C4 said. If the water was carbonated, that is... keyshawn?

supersix2

The water was not carbonated, it was just regular water. Perform the experiment yourself. Put a half empty bottle of water and a full one in your freezer and leave it for 8 hours and see which one is frozen.

pig

Not to nitpick, but wouldn't the freezing temperature have to be raised for this effect to occur?

Secondly, as a follow up on supersix2 (hate to keep treading on your toes ), but if the time derivative of the temperature roughly scales as the spatial laplacian of temperature, then, then scaling analysis roughly indicates that a difference of one quarter of the volume (with constant radius, this implies one quarter of the height) could be expected to render a difference in temperature change on the order of sixteen times faster, give or take. I would argue that the difference in volume would matter less at longer time scales, not shorter ones. Basically, ten days later they would both be frozen; on shorter time scales, the smaller volume freezes first, which is confirmed by the observation which we are discussing.

__________________
You don't love me, you just love my piggy style

supersix2

Precisely pigglet.

C4 Diesel

It would be compressed, but think of the shape of the water bottle. The height is significantly greater than the diameter, even at 75% full. Therefore the radial temperature profile is much more significant than the vertical one because most of the heat transfer is going to occur through the sides. That's what I meant... Not that it doesn't change the profile, just that the change is relatively insignificant.

Oh, and sorry for the confusion between the bottle being open and opened. So much for convection.

Wait a minute... I believe we're all forgetting something here... Water is a LIQUID!!! Therefore it flows within itself (because of simple molecular motion) which to a great degree evens out whatever temperature gradient may have occured if the mass was solid. This being the case the rate of the temperature (energy) change is based only on the conductivity, thermal mass and surface area / volume ratio. Since the conductivity is constant and the surface area / volume change is not large (small increase?) then the only factor reamining to play a role is the thermal mass. The SA/volume ratio remaining relatively constant idea depends a lot on the shape of the top of the bottle. If it was semicircular (low SA/volume), then I may have to toss this idea out the window since this area of the bottle was the area vacated in the 3/4 full bottle (and yes, a smaller cylander would have a greater SA/V becasue the surface area of the ends does not change). Either way, I would expect the reduction in thermal mass to play a greater role than the increase in SA/vol.

__________________
C4 to your door, no beef no more...

pig

C4 - Ok, now I understand your position more clearly. Without having aspect ratios, it's tough for me to say exactly what the radial vs. axial resistance will be, etc. You are probably correct, unless we're talking about one of those little weirdo bottles that I've seen. Let's assume we're talking standard 20 oz. bottles, in which case I would agree. I also think that the radial distribution will be, more or less, the same in the full bottle versus the 1/2 empty / 1/4 empty bottle, so I'm not sure how much of a factor that makes. I'm taking it as a separable solution (big assumption, but common in practice I believe).

This is an important assumption as well...I believe that for significant flow to occur via natural convection, rather large density changes are required. I agree that this affect occurs, no doubt. The fluid is also tightly confined by the bottle, if it's a 20 oz., which also has affects on the flow. Natural convection, as I understand it, is much more pronounced in homogeneous gases than in homogeneous liquids.

This is the statment that I am not so sure about, at least in the way you mean it. I still believe that the temperature difference between, say 25 deg. C, and 0 deg. C is going to be a larger factor, at least at first. However, I will agree with you that the center of the liquid will be cooling due to conduction affects, and some convection affects, and this will tend to decrease the temperature gradient. However, any type of diffusive/conductive transport will be a function of the conductivity, the thermal mass (which is essentially the specific heat, correct?) and SA/V. I just don't think that the water is isothermal.

I'm not so concerned about the reduction in SA/V ratio, as the increase in heat flux on the smaller volume. I will wholeheartedly agree that there will be affects related simply to the smaller volume of the cylinder that is 1/4 full...as I said before, I just don't think that the cylinder is isothermal, and that the rate of cooling / phase change is strongly affected, although not completely dominated, by the rate of the heat flux within the liquid. Note that if the water is considered to be isothermal, then the heat flux within the cylinder is more or less zero, and this would imply that the entire bottle would freeze more or less instantly. As I said before, I've never actually performed the experiment in a controlled fashion, but I believe that the water tends to freeze first at the edges, and the phase boundary moves into the center of the volume. Is this not correct?

Either way, it's been fun discussing (I would say arguing, but that term has certain negative connotations that I would prefer to avoid) the subject.

__________________
You don't love me, you just love my piggy style

ICER

Here's a shot in the dark. Could the impurities in the open bottle be a factor?

__________________
What's the difference between congress and a penitentiary?
One is filled with tax evaders, blackmailers and threats to society.
The other is for housing prisoners.
~~David Letterman

ICER

OK, get ready to groan, because once again I tried this experiment at home.

Experiments items
3 bottles of .1L (1PT, 0.9FL oz) Ozarka water
1st Opened with 1/2 cup poured out. Lid screwed back on
2nd Opened with no water poured out. Again the lid screwed on
3rd Unopened

Placed in freezer at exactly 2:00 am
Removed from freezer at exactly 10:00 am

Results. All the water in all three bottles were frozen solid.

Well. From this I would say that it doesn't matter if the container is open or closed. Or how much water is in it. Placed in a freezer for 8 hours. It all freezes

Granted my freezer was colder in the subject's car. So maybe it takes longer for the unopened bottle to freeze. I'll run another experiment tonight to see how long it takes them to freeze

__________________
What's the difference between congress and a penitentiary?
One is filled with tax evaders, blackmailers and threats to society.
The other is for housing prisoners.
~~David Letterman

coldhands

What kind of car was it?


(Sorry to make fun, but I could not resist. Actually, I really enjoyed this tread and the fact that right or wrong, people are thinking about science, and that's great!)

__________________
"All it takes to make a difference is the courage to stop proving 'I was right' in being unable to make a difference, to stop assigning cause for my inability to the circumstances outside myself, to be willing to have been that way, and to see that the fear of being a failure is a lot less important that the unique opportunity I have to make a difference."

-Werner Erhard

saltfish

This experiment must be replicated, though time = 8h needs to be changed to time = 3 hours.

Yakk

Hmm. Lets say the full bottle was 400 ml, and the 3/4 full one 300 ml.

And lets assume they started at 30 degrees C.

The 400 ml one would take 12 kCal (30 * 400) to cool down to 0 degrees without freezing.

The 300 ml one would take 44 kCal ((30+80) * 300) to freeze completely, and would start icing up after 9 kCal.

Nope, no answer there.

__________________
Last edited by JHVH : 10-29-4004 BC at 09:00 PM. Reason: Time for a rest.

choskins

Was it Aquafina or Dasani?

__________________
"Sometimes a cigar is just a cigar."
- Sigmund Freud

C4 Diesel

It is, but it's still significant in liquids except at very low temperatures. Let's do some math, shall we? Say the water was at 10*C, (283K or 50*F) since the car was probably warmer than that when he stopped driving, but the water temperature had probably not equilibriated. One Kelvin is the energy equivalent to 1 cal/mol for water (it takes 1 cal to increase the temp of 1 mol of water 1 K). So assuming all the 273 K worth of energy goes into rotation since that's the point at which the molecule stops rotating and starts vibrating and the other 10 K worth of energy is in the form of movement. In all likelihood, it's probably more than that, but it's AT LEAST that much. So that makes 10 cal/mol which is equivalent to 41.84 Joules/mol. Now the kinetic energy formula tells us KE = 1/2*m*v^2. The mass of a mol of water is 18 grams, or 0.018 kg to keep standard units. So v = sqrt(2*KE / m) which equals a little over 68 meters per second. Granted, they are not actually moving across the bottle a few hundred times because they are colliding with each other and probably stay in relatively the same place, but I would argue this is enough molecular motion to keep the bottle fairly isothermal. Even at 2*C you would get about 30 m/s.

To answer your question... Thermal mass is the specific heat multiplied out by the mass of the object in question and its temperature. It's basically a measurement of how much energy (heat) it has, but in this case they are fairly interchangable since they relate directly to each other.

The way I see it, the actual temperature difference across the plastic will only matter if the water or the air is not considered to be isothermal isothermal (which I believe them both to be). Aside from that, I don't know how the temperature difference would effect the bottles differently

If the SA/V ratio did not change, then the heat flux would be proportionally less in the smaller volume than in the larger one due to the smaller surface, and not greater as you stated it. This actually supports the bottles reducing in temperature at the same rate. I take it this isn't actually what you meant, however, so I'll leave that one for you to think about again.

The heat flux within the cylander being zero is not the case. This would lead to the ouside freezing immediately and then insulating the rest of the mass. What an isothermal situation implies (under an ideal isothermal assumption) would be that the flux within the mass is INFINITE, that is as soon as there is a heat change in the system, the entire system instantly equilibriates itself. Whatever caused the change in heat still has to deal with the heat capacity of the mass, so the temperature of the mass and the environment would not instantly equilibriate, however.

__________________
C4 to your door, no beef no more...

C4 Diesel

IT WAS PENTA WATER!!! HAHAHAAHA!!!

...now where'd that thread go?

__________________
C4 to your door, no beef no more...

ICER

heh heh, Now that's funny

__________________
What's the difference between congress and a penitentiary?
One is filled with tax evaders, blackmailers and threats to society.
The other is for housing prisoners.
~~David Letterman

RCAlyra2004

OK I think that all of you have missed the point (but only slightly...)

I live in a northern climate far north of the america border... I see this stuff daily..

In highschool we used to add small stone chips to beakers of water when we were heating them in order to get the water to start boiling at a lower temperature. (The water would actually boil at 212 Degrees just like it was supposed to) The water would form bubbles on the tips of the stone chips and boil before reaching a superheated stage.

I remember well when our science teacher showed us how you could Superheat (Heat higher than 212 degrees) distilled water in a perfectly clean beaker. Once it started to boil it would all boil off in a flash and bubble over the top very quickly... it was almost like an explosion.

Well... for your information you can also supercool distilled or bottled water to well below 32 degrees F. especially if it is perfectly clean and (ha ha ) and has no backwash from your mouth in it. (hence the difference between the two bottles)

I suggest that the water in the unopened bottle was actually supercooled to the degree that the ice crystals had not yet formed.

I have seen this:
I saw the most amazing thing one winter morning when I left a 5 gallon Jug of Bottled water in my trunk over night. ... I remembered it when I woke up and expected the jug to have burst in my car. I went out to my car and the Jug was completely liquid. but it was still -8 Centigrade. I picked up the jug and carried it in to the house... when I set it on the kitchen table with a thump it spontaneously started to produce crystals in the water... the whole jug turned to ice in about 15 seconds... and the whole family saw it. ... it was spectacular! .. until the top of the jug cracked....

We also have similar problem with fresh water forming ice deep underwater on the structures of our power stations. Because the water moves so quickly through the river it can become super cooled without freezing. It is weird to see large patches of open water when it is -40 outside. But as soon as the water touches the concrete structure of our dams is freezes and can even plug the passageways. This is called frazzle ice and it has hampered our ability to generate power during winter months. Usually we can alleviate the problem with good engineering or by temporarily closing the passage way so the water rebounds to it's normal state... not frozen...

Check out this link for more info on frazzle ice or super cooled water.

[http://www.undercurrentsonline.com/f...messageid=849]

EDIT >>> Sorry... link doesn't work and I don't know why but here is the letter in full... attached below It's been a sl "ice"


RCALYRA

__________________
Living on the edge of sanity

C4 Diesel

I don't think "moving fast" is a condition that allows supercooling. Agitation is normally a condition that causes nucleation and propagation of phase change. I would be interested to know why this phenomena occurs, though.

Also, supercooling normally does not occur, even in a "clean" water supply. I'm not questioning the added energy requirement necessary to overcome the surface tension which occurs when a particle of a different phase is created, it's just that ordinary water (yes, even distilled water) is normally not that clean. There is already particluate in it which acts as a nucleation center and greatly reduces the surface tension of the new phase. Water that is actually clean is called nanopure water, and we buy it to make buffers which will be used in chemical detection instruments.

The jug thing baffles me. The entire contents turned to ice? The enthalpy of fusion of ice is 334 joules per mL (or gram). This is 80 calories. Even assuming that 1/4 of the jug froze and this was enough to break it, that would still mean that the water was at -20*C.

...Oh, and don't think it's not cold here. I'll wake up and it'll be -25*C (-13*F) here, so it's not like I don't know cold.

__________________
C4 to your door, no beef no more...

pig

C4 : Just for my clarification, you are stating that molecular velocities would be minimum 30 m/s, not that natural convection flowrates would approach this velocity? I believe the question would be how many collisions occur, how fast does this translate into the transfer of energy, and does this transfer occur via conduction or convection? Perhaps I am incorrect?


Thank you - that is more or less what I was assuming, based on energy balances, etc.

Precisely. I disbelieve that the water in the bottles is instantaneoulsy isothermal at the beginning of the experiment, you do.


I agree that there is a small increase in SA/V ratio as the volume decreases, as far as the liquid phase is concerned. The statement you make above concerning the heat flux is also based on the concept of isothermal conditions in the liquid, so that becomes the crux of the discussion, as far as I can see (notwithstanding the post above concerning the affect of saliva / contamination on the freezing point of the liquid - let's assume the bottle was opened and the contents poured into a cup?)

I agree - and I understand what you are saying. At the same time, if

q=-k*del(T), and del(T) = 0, then this has certain implications. There will be no flux of heat within the phase, as there is no driving force for transport, as far as I understand it. How the phase responds to change is another issue, as far as I understand it, and nothing in reality approaches the idealized case of the responsive isothermal phase.

I agree with these statement wholeheartedly, but question their validity outside the theoretical world. Heat, in the form of kinetic energy, must be transported out of the bottle somehow, and I claim that the primary mechanism is via conduction, although natural convection will undoubtedly occur. You seem to be stating that natural convection affects will dominate in some fashion, such that the contents in the bottle tend to stay at nearly isothermal conditions and warmer contents from the interior will tend to go to the cooler areas, due to density differences, and exchange heat at the boundaries. Is this a correct summation of your position? Otherwise, what mechanism due you propose is responsible for the heat transfer? I understand your molecular calculations, and although I didn't check the numbers I'll trust your accuracy. As I understand it, conduction is an averaged engineering approximation for molecular collisions due to their kinetics energy, convection tends to be dominated by density differences or pressure forces. Perhaps I am incorrect.

Thank you for your responses. I am enjoying this conversation, and as coolhands stated above, regardless of whether I am correct or you are correct, or it is a melange of viewpoints that is correct, I am simply happy that we can dork out on heat transfer.

__________________
You don't love me, you just love my piggy style

ICER

OK, experiment #2

Exact same bottles of water (thawed of course) Placed in the same freezer for exactly 3 hours.

Results: Although they were not frozen solid, (the centers were still in the liquid state) they all froze to the same extent. No difference at all.

Maybe I'm missing something. But so far. I have not found any evidence to support the claim that one could freeze while the other did not unless something was added to promote the freezing.

Tonight. I will place them in the freezer for 1 1/2 hours. But I really don't see anything different from what I have been seeing so far.

__________________
What's the difference between congress and a penitentiary?
One is filled with tax evaders, blackmailers and threats to society.
The other is for housing prisoners.
~~David Letterman

C4 Diesel

Molecular velocities. I got lazy and didn't want to actually bother calculating the actual conductive heat transfer in the water itself. You can do this with the density and some other junk to get the mean free path, which then with the velocity can give you the collision frequency. Assume a collision efficiency and you'll get a relative energy transfer per collision. Take this and the mean free path and the collision frequency and you can figure out how fast the energy is moving relative to the energy difference in the container. Again, I'm lazy and don't feel like doing this math nor do I feel like remembering the formulas (or looking them all up).

Well... We can do the above math and figure out which one of our assumptions is more correct, although I don't really feel like it (nor do I have the time now) so we'll leave it up in the air for now.

Sure it does. Put a gas in a bottle, for example. That'll stay very isothermal, even with no convection. It's all dependent on molecular motion.

Well, when I initially said that water inherently "flows" I meant moreso that it moves freely on a molecular level than it actaully flows as a whole. So yes, this molecular motion is still conduction and not convection. While water is a good insulator in the sense of it having a high specific heat, it is a poor "insulator of itself" if you will, because a large degree of molecular motion quickly evens out the heat within the system.

The heat removal through the plastic is obviously conduction as no mass is flowing through the plastic, but I'm sure you understand that.

We most definitely are dorking out. Haha...

__________________
C4 to your door, no beef no more...