[Bored chemist]

It's not as easy as you thought it would be.

Have you tried?

when heat transfer with the environment has been significantly reduced.

The point is that "reduced" isn't good enough, is it?
If you have heat flowing in, you don't have an equilibrium so this

can't maintain the temperature equilibrium

is meaningless.

It's now pretty clear that this thread has no point.

[hamdani yusuf (OP)]

Do you actually believe that your experiment yielded any useful information?  Let me assure you it did not.

If you already have a conclusion which is unfalsifiable and unaffected by experimental results, then my experiments would be useless to you. But they might by useful for anyone else trying to stabilize temperature of a system in a real world environment.

[hamdani yusuf (OP)]

Have you tried?

Yes. Read again my posts here.
 If I can isolate the system completely by any way, I'd like to test it.

[Bored chemist]

But they might by useful for anyone else trying to stabilize temperature of a system in a real world environment.

If that person hadn't previously been aware of an ice bath as a way to get some degree of temperature regulation.

Yes. Read again my posts here.

I did not notice the post in which you adopted my suggestion and enclosed the whole apparatus in a tank containing a slurry of ice and water.
Please point it out.

If I can isolate the system completely by any way, I'd like to test it.

You can...enclose the whole apparatus in a tank containing a slurry of ice and water.

[alancalverd]

f I can isolate the system completely by any way, I'd like to test it.

It cannot be done, which is why heat experiments are very difficult.

BC's slurry tank will get you some of the way, maybe with in 0.1°C of constant temperature, but you need to keep stirring the slurry to stop the bottom of the tank getting warmer. If you add more ice, you will cool the top below 0°C, so you have to choose the right moment to do your measurements. And you need to seal the top of your experimental rig to stop ambient air getting in. Problem is that with ±0.1°C uncertainly, you won't be working anywhere near close to the textbook statement of "equilibrium". And you still have the problem of not knowing the temperature in the middle of your experimental ice chunks, even if the exterior slurry is well mixed.

So you would probably do better to use a thermostat tank of glycol antifreeze and a chiller coil to bring it down to zero. Keep stirring but at least you know it won't contain any chunks of sub-zero ice or anomalous convection. Then prepare your experimental ice by some magical method that doesn't involve a sub-zero chiller.   

[Deecart]

So, heat flow can occur without temperature difference?

By definition, no.
Heat is a macroscopical physical quantity.
It is the energy of some mass at some velocity.

But if you go further and further with less and less mass (at least you end up with some single molecules, and here you go out of the thermodynamic domain and enter into the more fundamental physic), you end up with local interactions that do not have the behavior of the macroscopical law.
So (at equilibrum) you end up with "fluctuations", no "flows".

The fluctuations also exists within the macroscopical domain, but they are discarded (because of the null result at this scale).
So when you talk about heat flow, like when you talk of every flow (flow of liquid in the river per example), you have local molecules doing random transitions ("at equilibrum) having nothing to do with the macroscopical law.
Some water molecules go temporaly up into the river !

To summarize :
At macroscopical level, you have 2 phenomenon occuring : The flow and the fluctuation.

[Bored chemist]

f I can isolate the system completely by any way, I'd like to test it.

It cannot be done, which is why heat experiments are very difficult.

BC's slurry tank will get you some of the way, maybe with in 0.1°C of constant temperature, but you need to keep stirring the slurry to stop the bottom of the tank getting warmer. If you add more ice, you will cool the top below 0°C, so you have to choose the right moment to do your measurements. And you need to seal the top of your experimental rig to stop ambient air getting in. Problem is that with ±0.1°C uncertainly, you won't be working anywhere near close to the textbook statement of "equilibrium". And you still have the problem of not knowing the temperature in the middle of your experimental ice chunks, even if the exterior slurry is well mixed.

So you would probably do better to use a thermostat tank of glycol antifreeze and a chiller coil to bring it down to zero. Keep stirring but at least you know it won't contain any chunks of sub-zero ice or anomalous convection. Then prepare your experimental ice by some magical method that doesn't involve a sub-zero chiller.   

I didn't specify all the experimental details of how you make sure the temperature is maintained rather better than 0.1C.
The most notable is that you circulate the water with an external pump and ensure that , just before it reaches the "experimental" tank, it flows through a chamber containing lots of ice. If some of that ice is a little below 0C it doesn't matter because it won't supercool the water. The advantage to using water and ice, rather than a cooling coil and glycol is that it's "self calibrating"
You are, of course, perfectly correct in saying it's very difficult.
I have to admit the technique isn't really "mine". It was developed by some "famous names".
https://www.nature.com/scitable/content/ice-calorimeter-developed-by-lavoisier-and-laplace-14898943/
I think you and I could happily while away an hour or two discussing tweaks to improve thermal isolation over a glass of something, that's not really the point.
My point was that, while the answer given to

Have you tried?

was

Yes.

it seems pretty clear that the correct answer is "no".

[alancalverd]

I'm now considering the matter for amusement only, but it does while away the time on the M25 when all else is silent and unmoving.  Here's a suggestion:

Using a well-stirred circulating glycol tank with an external chiller (thanks, BC) you can gradually reduce the temperature of a gently-stirred sample of pure water. The volume of the sample will increase as ice forms. Now hold the temperature at 0°C. If there is a heat flow between the water and the ice, the sample volume will change as the water melts the ice or vice versa. 

[hamdani yusuf (OP)]

But they might by useful for anyone else trying to stabilize temperature of a system in a real world environment.

If that person hadn't previously been aware of an ice bath as a way to get some degree of temperature regulation.

My experiment shows the limitation.

[hamdani yusuf (OP)]

I did not notice the post in which you adopted my suggestion and enclosed the whole apparatus in a tank containing a slurry of ice and water.
Please point it out.

Here's my idea to minimize noise over signal:
- Prepare 50/50 ice-water mixture at around 0°C in a large plastic bowl. Let it in refrigerator for an hour to reach equilibrium.
- Fill a metal cup with 90% water and 10% ice from the mixture.
- Fill another metal cup with 10% water and 90% ice from the mixture.
- Put both metal cups into the bowl containing the remaining of the mixture.
- Let them in refrigerator for an hour to reach equilibrium.
- See the result, if the ratio of ice-water in the cups change.

OK. I've finished my first round of experiment as described above. But I can't get the metal cups, so I just used ordinary drinking glasses. I guess the heat conductance is enough for this experiment since they are quite thin.
The temperature of the refrigerator is 4C, as shown by a thermometer left there for an hour. The result is the ice in both glasses decreased from initial ratio.
So I moved the system to the freezer, which is kept at -4C, as measured by a thermometer left there for an hour. The result is the ice in both glasses increased from initial ratio.
These results show that energy transfer between the system and the environment overwhelmed the energy transfered through the glasses. It means that the noise over signal ratio is too high to get reliable conclusion. Hence the experimental setups need to be improved.
I also learned that gravity and buoyancy play significant role in determining the results, which need to be addressed in upcoming experiments.

[hamdani yusuf (OP)]

I have to admit the technique isn't really "mine". It was developed by some "famous names".
https://www.nature.com/scitable/content/ice-calorimeter-developed-by-lavoisier-and-laplace-14898943/

The top side looks uninsulated, which can cause heat leakage.

[Bored chemist]

The result is the ice in both glasses decreased from initial ratio.

That's the bit which proves that you hadn't thermally isolated them.
And that shows that they were no surrounded by material at 0C.
What sort of lids did you use on the cups?

[hamdani yusuf (OP)]

What sort of lids did you use on the cups?

Just a simple plastic plate. I thought the air below it would provide adequate heat insulation.

[Bored chemist]

What sort of lids did you use on the cups?

Just a simple plastic plate. I thought the air below it would provide adequate heat insulation.

So, the test samples weren't actually completely surrounded by ice/water?

[JosephCook]

I'm now considering the matter for amusement only, but it does while away the time on the M25 when all else is silent and unmoving.  Here's a suggestion:

Using a well-stirred circulating glycol tank with an external chiller (thanks, BC) you can gradually reduce the temperature of a gently-stirred sample of pure water. The volume of the sample will increase as ice forms. Now hold the temperature at 0°C. If there is a heat flow between the water and the ice, the sample volume will change as the water melts the ice or vice versa.

Uhm, your theory sounds interesting, have you tried it?

[hamdani yusuf (OP)]

So, the test samples weren't actually completely surrounded by ice/water?

No.
I'll submerge them in next experiment.

[Bored chemist]

No.

So, just to clarify things, when you said

Yes.

You actually meant

no

[alancalverd]

Uhm, your theory sounds interesting, have you tried it?

I have used ice/water calorimetry in the past, and as I keep repeating, it is extremely difficult, even with the resources of a national standards laboratory, to do well. To attempt to use it to disprove the most fundamental statement of thermodynamics using domestic kitchen equipment, is beyond foolish.

[Bored chemist]

To attempt to use it to disprove the most fundamental statement of thermodynamics using domestic kitchen equipment, is beyond foolish.

And thus  Alan wins today's award for "most understated assertion".

[hamdani yusuf (OP)]

No.

So, just to clarify things, when you said

Yes.

You actually meant

no

I have tried several tweaks to the experiment. That's what yes means. You seem to have short memory problem, which makes you often make straw man argument.

I replaced the glasses with small plastic bags, which were almost completely submerged. But the results were the same. That's why I tried to find another method.

I also learned that gravity and buoyancy play significant role in determining the results, which need to be addressed in upcoming experiments.