water freezing still remains a mystery

Cecil's Columns/Staff Reports
1

Yeah, since your answers on the subject of water freezing did not make me convinced, and I couldn’t find a way to answer, I must start a new thread.

Now we have a given temperature of very VERY hot water (sample B), and a variable temp less hot water (sample A).
It was stated that at certain temperature B will freeze quicker than A.

If, however, A being very cold, will freeze quicker than B, there must be a turning point
somewhere in between., where A once again begins to freeze faster.
Another turning point comes when temp of A exceeds B.

On the basis of high-scool Calculus, it can easily be seen that when y-axis is the speed of freezing,
and x-axis the temperature of sample A, and there are two min/max values, it must be due to
an equation of third degree.

I would like to know if anyone has ever tried to come across of the exact representation of this equation.

Yes, I’m confident that this is not simple in any way, and that the whole matter is of insignificant importance.
But, what the hell, do we have any more inspiring issues to talk about in the pub.

2

Mathmeticians and physicists don’t hang out in the same pubs I frequent. However, I saw a play recently in which a woman talks about the night before, when she partied with mathmeticians and physicists. The experimental physicists decided, as a project, to find out how much she could drink.

There’s a good chance I’ve spelled something wrong in this post, but I don’t see the mistake right now.

3

One of the basic fundamentals in thermodynamics is that a greater difference in temperature (spoken as delta T) will have a faster RATE in change of temperature.

The hot water is FASTER, the cold water is SOONER.

4

Welcome to the SDMB, and thank thee for posting thy comment.
Please include a link to Cecil’s column if it’s on the straight dope web site.
To include a link, it can be as simple as including the web page location in thy post (make sure there is a space before and after the text of the URL).

Cecil’s column can be found on-line at this link:
Which freezes faster, hot water or cold water?

moderator, «Comments on Cecil’s Columns»

5

Okay, I reread the column, then reread what you wrote. Here is the detail that I think you missed. The very VERY hot water (B) will evaporate a portion of the contents before it cools significantly. In fact, evaporation will help cool the water. Thus it cools faster than sample A, the only moderately very hot water. However, at this point sample B contains less water than sample A. Thus, sample B continues to cool faster, because there is less of it to cool. Thus, sample B reaches freezing first. QED. Ipso facto. Ergo. Or something like that.

Or to restate less verbosely, the missing factor in your plots is mass.

6

Step one: Measure the water’s temperature.
Step two: Freeze the water. Take note how much time passed for freezing to take place.
Step three: Calculate “speed” of freezing using the following equation:
Speed=Temp/Time
This will give you a Degrees Per Minute answer.
Step Four: Repeat steps one through three using water of a different temperature.

Results: The hotter water will have the greater speed, EVERYTIME!

Sooner does not mean faster, Cecil Adams. For 14 years you have been spreading faulty info. Shame on you.

7

Horsepucky. And likewise, piffle. No one asked, and no one cares, which COOLS faster; they ask which FREEZES faster. Freezing is a finish line: in other words, freezing sooner IS freezing faster, dummkopf, and cold water crosses it first. If you use sealed containers instead of an ice cube tray, cold water freezes first EVERY TIME (note: two words).

Try an intelligent critique instead of a pseudoscientific semantic “gotcha,” next time.

8

Here it only needs to be second order. The time to freeze as a function of initial water temperature could be a parabola, with the minimum values at T = 0 and T = 100 C, and a maximum somewhere in between.

9

quote:

On the basis of high-scool Calculus, it can easily be seen that when y-axis is the speed of freezing, and x-axis the temperature of sample A, and there are two min/max values, it must be due to an equation of third degree.

Here it only needs to be second order. The time to freeze as a function of initial water temperature could be a parabola, with the minimum values at T = 0 and T = 100 C, and a maximum somewhere in between.

Yes, but you cannot deny that within 0 and 100 celcius degrees, if we make laboraty tests wtih given temp B
and variabale temp less hot A, the resulting curve can be traced back to an eq. of third ORDER. (if you like)

When T1 is 0 and T2 100, it is certainly an exception.

The ancient Romans said something like “there is no rule without an exception”
So we can and we will find an equation out of this mess, and exceptions will later be regarded as
supplementary knowledge factors only.

In the first place, I didn’t say this was an easy task, did I ??

10

Cite, please.

11

I am just wondering if anyone has tried this experiment with some control factors. I would hope it’s not tried in a conventional home freezer, especially a small one. What I’m getting at is hot water may just trigger the themostat in the freezer for a longer period of time thus pumping in more coolant than a colder sample. I hope I can find the answer before I die.

I love the little tacos, I love them good.

12

Cecil’s column on exceptions proving rules may shed some light on this.

13

I can’t believe y’all don’t know why hot water freezes faster. I’m really not too bright, but I learned about this in jr high!

Thermometers which we say measure “heat” in reality measure “kinetic energy” or “energy of motion.” That means that hotter water is just hotter cause it’s moving faster. That’s why when things get really cold they freeze, right? They virtually stop moving - but nothing actually stops moving till absolute zero (0 Kelvins).

Basically, hot water freezes faster cause water has a “v” shape (the oxygen at the bottom point and the two hydrogens at the peaks). It has to line up perfectly to freeze (which is why ice floats). Since hot water is moving faster, it can more easily come together in its appropriate pattern, and therefore freezes faster.

Did that make sense or did I just ramble?

14

A whole new era of undetermined physics has just begun.

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 'Basically, hot water freezes faster cause water has a "v"    shape (the oxygen at the bottom point and the two hydrogens at the peaks). It has to line up perfectly to freeze (which is why ice floats). '
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This is true. When water crystallizes, it leaves enough empty space between molecules; hence it is not as heavy as ‘free’ molecules at 4 degrees celsius.

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Since hot water is moving faster, it can more easily come together in its appropriate pattern, and therefore freezes faster
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This, however, doesn’t make any sense. Heat (energy) causes small particles to spin around quicker, so why would the molecules
want to lock into one freezing position rather than keep on spinning ?? If this was the case, that more energy leads to more
likely crystallizing, then I suppose that the whole Universe should
have been freezed completely from the very beginning.
Anyway, the starting point for this discussion was that water is supposed to have an unique property of freezing faster at very high temp than at less high temp, but it still freezes faster at very low temp. So, as I have many times pointed out before, if we find an equation to define behaviour of water, it must be of at least
3rd order. If your statement should turn out to be true, then this equation woud be of 1st order.
By the way, has anyone thought about freezing point of iron or gold ??
These, and all other substances/elements, have their own unique
characters and properties, and I just wonder; what if we had this same problem with these metals ?? Does gold freeze quicker when it is VERY HOT ?? Quicker than less hot gold.
No, I don’t think so.

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  'I am just wondering if anyone has tried this experiment with some control factors. I would hope it's not tried in a conventional home freezer, especially a small one. What I'm getting at is hot water may just trigger the themostat in the freezer for a longer period of time thus pumping in more coolant than a colder sample. I hope I can find the answer before I die. 
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Now, this sounds familiar: it is straigth from the so called
‘Heisenberg uncertainty principle’.
Yes, it is a fact that any property to be measured affects the results. But there is no problem with this; the possible error just has to be taken into account, when rewiewing the results.

In the beginning of this mystery-to-be-solved, someone wrote to Cecil and asked (something). Cecils final argument was
‘I rest my case’. First I believed, because Cecil is always right (right ??)
But now we have doubts about reliability of tests that Cecil did carry out (if hshe ever did any !!)
In order to find The Truth about this matter, we have to establish
an independent international committee to study the problem. They would have full equipment of high-precision-instruments
and ,keeping Heisenberg in mind, they would also need a group of psychologists to determine whether the results were affected
by scientists themselves (!) or not.

15

Regarding the OP, the fact that a function has a single miniminum and a single maximum does not necessarily mean that it’s a third-order polynomial. I’m sure that if this function has an actual shape, it’s more complicated than that.

If I’m doing the differential equation in my head correctly, then Newton’s Law of Cooling suggests that to for a large temperature (T), the time (t) to freezing should behave like t ∝ ln(T - T[sub]0[/sub]) + C.