Watching Water Freeze

If he's outside, you also forgot to mention wind chill. Wet bulb, whatever. It will make a difference. Other than that great answer.

I rated sb's answer a GA, one of the best I have read. He/she illustrates by specific example the absurdity of the original post question. Reductio ad absurdum. I can't understand why sb's post is rated off-topic. It is a specific reply to a specific question.

I would guess his answer is off topic because it is way to complicated and does not answer the question about determining the freezing temperature of water by watching a specific volume of water freeze.

The simple answer is no

You can not determine the temperature by watching a volume of water freeze. Volume has nothing to do with the temperature at which water freezes. It has to do with the amount of energy released by the water as it cools and the latent heat.

If places in a dry ice bath, water will cool at a relatively consistent rate which can be plotted by placing a thermometer in the water. It will then stall at the freezing point as it releases latent heat. Once it has fully transformed it will again cool at a fairly consistent rate until the next structural transformation (Ice has different crystalline structures that occur at different temperatures). Thus if you measure the temperature directly you will get an inverse s curve for the inflection that occurs at freezing point. Doing any measurements using freezing from atmospheric temperatures, conductivity of containers, andf the change in water volume is in theory a way to measure freezing, but is highly inaccurate as water changes volume throughout cooling, conductivity changes with temperature changes, thermal cpacity and conductivity of water change with different impurities, and atmospheric temperatures are not an accurate measure of the energy extraction capacity. You should always measure the temperature of water directly. You can however, reasonably plot water temperature against volumetric change to determine an estimate of the temperature at which freezing occurs (instead of temperature versus time), then you do not need a cooling source substantially cooler than water, though you still may get errors do to inaccuracy in volumetric change due to cooling (it is only one source of error to account for).

Hello sb,

blooming good answer my friend! Apparently the OP marked an earlier post by you as off topic. I do not see how any of your posts were off topic? Funny some people, you try and help them and they slap you in the face! Metaphorically of course.......

You got the GA for a great piece of explanation.

GA on its way.........!

I am somewhat lost at your definition of "observing" because I am not able to determine the relationship you have between the "time to freeze" and the "freezing temperature". Some clarification of this relationship would be very helpful to the construction of a solution.

Hey SB you are a star

However you lost me on a! Still a thousand thank youz

I ve a friend with a functionning brain who will be here in March. So maybe some evening after a game of poker we will study your thoughts!

Listen I was hoping for something somewhat easier. Something that some Grec in 400bc might have done in his floral garden. F!!!k he didn't even have a stop watch!

Maybe had a grape froze solid in 10 minutes he would have said (refering to some table...) ok "i declare the temperature to be -15c" and added "the kids will need an extra hide tonight " and added "darling we need to cuddle"

I was hoping for an answer like "ok buster take a clear baloon full of 1 litre of water" If it freezes in half an hour well the temperature is minus whatever and if freezes in 15 minutes well the temperature is maybe twice as cold?...

Fair enough I take on board conditions will not ideal for the measurement still surely there is some means of getting an approximate measurment...

thanks!

ps : its gonna freeze here tonight so im ready for a simple caorse of action!

I like the balloon idea. Try it out and get back to us.

p.s. if your gonna do this during the poker game, easy on the alcohol. Your breath could disrupt the experiment

ok so i will cheat and have the real temperature handy and time the freeze...

i suppose I am bascially going to make the scale / table on a trial basis

this could be a legacy in the making

omg

Put the water out, dip two wires in it and let a small current flow through a resistannce and a battery, as soon as it freezes the condutivity will drop (I am not sure whether ice is a conductor or not, forgotten, even if conductor you can use an old wheatstone bridge) trip a relay to stop the timer and in the morning you have the time taken to freeze (Note start the timer as you start walking out of the warm room).

How is that for an engineering project ? But may be you can not do it tonight - you need a few appliances.

Even if you don't have a digital timer, you can put an ol' buzzer and sit in the warm room staring at the watch till it buzzes.

Pl run back to stop the buzzer- neighbors may bring in cops.

PS: I love topics which are so clearly off topic.

in fact filled a baloon with 500g of water.

Let it rest for hours in a room which was 15c

Then oiled it (will say later why) and placed it outside at 20:40 with the thermometer near by reading -5c

At 22:40 (after my Pilates and very hot shower) the water baloon was still liquid and the temperature was -5c. Not a hint of ice.

Got bored went to bed!

This morning 8am the ballon was solid!

So i missed that beautifil period of time at which it seems the ice is formed very very quickly. A true wonder to behold im sure!

Reminds me of opening a chilled can of beer and having it turn to slush in seconds. The stuff is liquid in the tin yet once opened god forbid it turns to ice! Anyway leave that for now i m hoping to work that one out with a elemtary chemistry book i plan to buy!

Anyway back to the topic, si ice did form but i don't know when si i cant begin creating some table of figures...

Oh yes and I had the baloon oiled as i was hoping to spin it in order to determine if is was solid the whole way through. Like a boiled egg will spin whereas a fresh one wont!

Isn't life fantastic!

If it freezes in half the time you can bet that the temp dropped significantly,much more than double.The temp would need to drop exponentially in seconds for the volume to freeze to solid in half the time.I don't want to be around your neighborhood if this happens there.

"...twice as cold."

I...it's...I mean...how does that even begin to...

*head explodes*

Ahh come on !

if -2c is cold well -4c is twice as cold!

things don't get more logical than that!

Arrrgh

Not that simple. In the Celsius temperature scale, there are 100 degrees between the freezing/melting point and the boiling/condensation point of distilled water, but 273.16 degrees between absolute zero and the freezing/melting point.

If you can get your hands on a copy, you might save yourself some trouble by reading Invention of the Thermometer by W. E. Knowles Middleton. I believe he goes into detail about development of the thermometric scales. I haven't read that book, but I have read Invention of the Meteorological Instruments by the same author. In his chapter he quotes from Fahrenheit's notes on his experiments to develop a thermometric scale, so I imagine he goes into more detail in the book about thermometers. Fahrenheit set zero on his scale at the freezing/melting point of salt water, instead of distilled water.

BTW, the ancient Greeks didn't have thermometers. Except for the rain gauge and the weather vane, most meteorological instruments didn't come along until the Renaisance. Galilleo is often credited with inventing the thermometer, but what he made was a thermoscope, a device that shows a change in temperature, but not how much the temperature changes. A thermometer has a scale attached to, or marked on it, so it can show the amount of change.

The real thermometer was invented on strips of plastic that changed colors to tell the temperature. You were suppose to stick them on the big rock that made your doorway away from the dinosaurs. (They liked the taste) But because the glue back then was inadequate we had to wait till the 20th century.

But it is

and seriously

provided

a) Water composition is more or less same - normally is.

b) Quantity of water is more or less same (say a cube of the ice pot)

c) Don't calculate, calibrate

d) Results next winter (or may be in fridge - put the electrode example i gave you sorry lazy to go through and give ref no)

Instead of all this experimenting in the buff and what have you, I am curious if it would have been better had we begun the attack on this question by starting out with a thought-experiment and continually shaped the experiment-structure until we honed in on an agreed upon construct and conduct of such experiment?

Unfortunately, you didn't state your original question clearly enough. I originally thought you wanted to find the freezing temperature of impure water by timing the freezing.

Now it appears that you want to determine the temperature of cold air by timing the freezing of a quantity of water. That is somewhat more logical, but still not practical. If you have pure water held in a smooth-walled container placed in a location where the surroundings are well below zero Celsius, the water will cool to several degrees below zero (freezing temperature) and remain liquid. This is referred to as supercooled water. It is beautiful to watch what happens next: If the container is then moved suddenly (tap it on the side), or a tiny 'seed' of ice is dropped into the container, crystals of ice will grow rapidly (a few seconds) through the water. Once the crystals stop growing you have a mixture that is guaranteed to be at precisely zero degrees Celsius (assuming pure water). Try it!

I am presuming your refering to water mixed with other solutes, the short answer is yes, but you need to know the percentage of mixture, the thermal conductivity of the container, the ambient temperature ( the lower it is below the freezing point the faster the sample will cool and solidify), also need to know the begining temperature, and the more precisely you know all of these values the more precisely you can determine the solidifiing temperature. the other relevant things to know are the BTU's required to be removed to solidify, and btu per degree change and this is a function of the ratio of solute and solvent. a good absic Chemistry book will have the information necessary to work all this out.

Or websearch on "bomb calorimeters" to study their construction, use, and calculations for determining specific heat, latency, temperatures, rate of temp change etc. Once you understand that then you can run through the math.

Me? I am more simple minded and will buy a wall hung thermometer to measure temperature!

First of all, you need the right qualifications. I propose a course in "watching paint dry".

After that, you need to design your freezing vessel so that it measures the right thing. Do you want to measure temperature as with a thermometer? Or do you want to include some effect of wind chill? If the former, you can use a small part-filled insulated paper cup with a transparent lid, placed inside another such cup and lid. If the latter, you want to place the water in a small thin-walled (again covered) vessel.
In either case you need to know the starting condition of the water - probably best pre-boiled and including a very fine suspension and starting from a known temperature close to freezing.

For actual temperature, I think it would be much more fun (and probably more repeatable) to use the proportion of the ice sitting above a solution of salty water; as more water freezes the liquid part becomes more concentrated so the water is less easily frozen. To make it easily visible, you use a coloured salt as part of the mix.

Are you again trying it tonight ?

I propose a cup of hot coffee , no alcohols and no distraction .

Sit in fron of TV and watch any exciting game (find out what is going on around even a boxing match will do)

If nothing goes on , rent a real horror movie (what about having a look ay me tonight ? or at one of my cousins ? I have a lot of them you know).

take off your warm suits, put off the fire/ room heater- the warm ambient will make you sleepy - and dont - repeat - dont count sheeps (or mice)

report tomorrow

PS: I really love to get GA points on on offtopic discussion (pssst dont tell the administrator)

See if you can find a description of Paul Siple's work in developing the wind chill index. I've seen an article that claims that he used water in a plastic bottle, but since he did the work prior to WWII, I doubt it! I recall reading that his early work was done using coffee cans full of water (coffee cans used to be maybe 6" (150 mm) across and 3" (75 mm) tall, and opened with a key to remove a strip of metal, like some sardine cans of later vintage.

Hello Everybody,

Please, let me restate my understanding of the initial question so that we may get with it: the gentleman/woman is going to stand in front of some quantity of water, and "observe" it until the water freezes, and then come up with the freezing temperatures. there is no clear definition of the method of observation: for all we know the person will simply be looking at the water until it freezes.

Again please, note that there is no discussion of measurement of temperatures, you guys are adding all that to help the question along, there is not discussion about the solutes in the water you guys are also adding that to help the question along.

Again please, does it matter whether the water is 1 litre or 2 liters as far as freezing temperature is concerned? Now does it matter how long the 1 litre quantity of water will take to freeze as compared to a 2 litre quantity of water?

These are my understanding of the question, but then I could be wrong. Yet that said, I think that while time to freeze will depend on the quantity of water, freezing temperature does not. Freezing temperature is an intrinsic ( or is it intensive ?) Thermodynamic property, I should think. Thermal capacity, however, is a function of quantity [or extensive Thermodynamic property] I do believe, if my memory serves me well.

Alright then consider these two questions:

i am wondering if it is possible to determine freezing temperatures by observing how long it takes a certain volume of water to freeze

i am wondering if it is possible to determine ambient temperatures by observing how long it takes a certain volume of water to freeze

Would you say that the two questions are somewhat different? If so how are they different, and if not why are they not difefernt?

The freezing temperature (all other things being normal) is 0 deg C for the water (distilled) or may be a bit below under normal circumstances with normal impurities whatever may be the volume of water.

The ambient temperature has no relation with the freezing temperature and will only make the water reach the freezing temperature (or below in ice form) - at a speed decided by newtons law in association with other physical phenomenon (eg conductivity etc)

Consider the case of SR or tempering.

The stress relief is done on steel at say 600-650 deg C (equivalent to freezing temperature)

But you hold it for 1 Hrs / inch - so that the whole mass reaches the uniform temperature (that is in case of a good conduttor like steel) (equivalent to freezing time)

Here it is not the question of phase change but what must be temperature so that the decided final temperature is reached in a time (on the reverse logic) so if the cat finde if the temp is -20 deg C he could freeze the water in 20 minutes do you see the significance on CCR?

As I said you can think on these angles (ever thought how this understanding can be used for HT of steel.

I really would have loved if somebody could mathematically model the system. But as my post has mentioned it is far too complicated isn't it ?

Should we argue on semantics ?

By the way CKTC (the OP) didn't come back after the threads advices (if i remember #25 and 20 with the sub-threads)

Then you must resort to the answer of dkwarner, below #36. His initial answer seems to have resurfaced again once the question has been reset more clearly.

That said I can tell you that I have taken some interest in this question because the Inverse Problem was a question in a PhD Comprehensive Exams I took many years ago. We were required to analyse the problem mathematically. The point I am making is that under certain prescribed ambient conditions - such as we would allow dkwarner to defined for us, of course, with extreme mercy - the problem could be mathematically modelled.

However, I still resort to the answer of dkwarner as GA.

Absolutely! They are quite different!

The first question implies determining the temperature at which some unspecified substance freezes. Since it also mentions freezing water, I infer that the unknown substance must be water with some kind and amount of impurity dissolved or suspended.

The second clearly indicates determining the temperature of the ambient, which is NOT a freezing temperature, but must be a temperature well below the freezing point of water in order for the experiment to work.

The answer to both questions is still NO, but for different reasons.

For the ambient temperature question, there are just too many variables: In addition to the supercooling mentioned previously, to obtain a correct answer you would have to take into account such things as the movement of air, both forced (wind) and natural (convection); the material (thermal conductivity), thickness, shape (surface area), and color (emissivity) of the container; The temperature, shape, color, and proximity of every nearby surface (radiant heating/cooling), and of course the initial temperature and agitation state of the water.

Obviously, an ambient temperature farther below the freezing point of water will make the water freeze faster, but this is just too slow and complicated a method to be useful. Since it is so slow, if you were to control all the variables, the answer would be the average temperature over the time it took to freeze, not the current temperature at the time it froze.