[hamdani yusuf (OP)]

So both had variable polarisations.

The polarizer was co-moving with the container, as well as the water. Thus, in the perspective of the water, the incoming microwave has constant polarization angle.

[hamdani yusuf (OP)]

I've uploaded another video investigating superheated water by microwave oven. This time I used a larger container to show inhomogeneity of the superheated water.

[Bored chemist]

So both had variable polarisations.

The polarizer was co-moving with the container, as well as the water. Thus, in the perspective of the water, the incoming microwave has constant polarization angle.

So the intensity would vary with time.
That's a troublesome confounding variable.

[Bored chemist]

I've uploaded another video investigating superheated water by microwave oven. This time I used a larger container to show inhomogeneity of the superheated water.

The video shows little if any superheating.
Most of the bubbles are dissolved air.
Incidentally, a smooth metal object isn't a good nucleation source. You might want to try a wooden spoon.

[hamdani yusuf (OP)]

How about demonstration of de-superheating while being superheated all at once? How much air can the water hold?

[Bored chemist]

How much air can the water hold?

Not very much, but if the water is nearly boiling then any air bubbles are also expanded by the presence of water vapour.
The release of dissolved air is also limited by nucleation sites. That's the basis of the Mentos and cola demo.

[hamdani yusuf (OP)]

How much air can the water hold?

Not very much, but if the water is nearly boiling then any air bubbles are also expanded by the presence of water vapour.
The release of dissolved air is also limited by nucleation sites. That's the basis of the Mentos and cola demo.

I repeated the heating for dozens of times with the same water, without the sign of reduced quantity of bubble in later tests. I don't think it came from the release of dissolved air.

[hamdani yusuf (OP)]

Here's another video on bumping

Boiling without boiling chips

And this is Flash boiling superheated distilled water

Are they the same phenomenon?

[hamdani yusuf (OP)]

Here's another interesting video

Adding sugar to superheated milk

Considering that commercial drinking water can not be superheated due to its impurity, it's surprising that milk can be superheated in this video. I'm not sure if it can be done for any kind of milk.

A Google search for milk substances gives me this.

THE CHEMISTRY OF MILK. The principal constituents of milk are water, fat, proteins, lactose (milk sugar) and minerals (salts). Milk also contains trace amounts of other substances such as pigments, enzymes, vitamins, phospholipids (substances with fatlike properties), and gases.

[hamdani yusuf (OP)]

Here's my video showing desuperheating by a metal coin.

[hamdani yusuf (OP)]

And this one shows superheating water with restricted direction of microwave.

[Bored chemist]

Are they the same phenomenon?

In what way do you think they are (significantly) different?

[hamdani yusuf (OP)]

Are they the same phenomenon?

In what way do you think they are (significantly) different?

Microwave superheated water can stay in superheated state longer when it's not induced to boil. It can last more than 30 seconds until it loses heat to surroundings.
How long can it last using other methods of heating?

[Bored chemist]

How long can it last using other methods of heating?

Exactly the same as with microwaves.

How would it know the difference?

[hamdani yusuf (OP)]

How long can it last using other methods of heating?

Exactly the same as with microwaves.

How would it know the difference?

I never see an experiment of superheated water that stays being superheated for long after the heating stopped. Just repeat my experiments, but use other heating methods instead of microwave oven.
I have tried to superheat demineralized water using infrared ceramic cooker. I used the same glass as my experiments with microwave oven. Unfortunately, the glass breaks down just before the water starts boiling.
Now I've got a borosilicate beaker which should be suitable for the experiment. Let's see what we'll get.

[Bored chemist]

I never see an experiment of superheated water that stays being superheated for long after the heating stopped.

Did you look?

If there's no nucleation site, and no heat loss (i.e. an insulated container) then you can maintain a superheated liquid indefinitely.

https://en.wikipedia.org/wiki/Metastability#States_of_matter

 

Now I've got a borosilicate beaker which should be suitable for the experiment. Let's see what we'll get.

You will get the kind of behaviour that explains why people were using anti-bumping agents a hundred years ago (and longer than that , but they are harder to prove)

[hamdani yusuf (OP)]

Now I've got a borosilicate beaker which should be suitable for the experiment. Let's see what we'll get.

Now I've done recording the experiments. These are what I did.
1. Heat demineralized water in the borosilicate beaker in microwave oven until some bubbles are formed. Then test if it's superheated using a steel fork.
2. Reheat the water using microwave oven, and repeat the test.
3. Reheat the water using infrared ceramic stove until some bubbles are formed, and repeat the test.
4. Reheat the water using infrared ceramic stove until some bubbles are formed, and repeat the test.
5. Compare the results to determine if they are produced by the same phenomenon.

Is there any missing step I should have done?

[hamdani yusuf (OP)]

Here are some other videos I took last year, but just finished editing.

Superheating Water With Linear Polarizer and Metal Basket

Plastic Button as Nucleation Site

Other Objects as Nucleation Site

De-superheating With Plastic Stick

[hamdani yusuf (OP)]

Now I've done recording the experiments. These are what I did.
1. Heat demineralized water in the borosilicate beaker in microwave oven until some bubbles are formed. Then test if it's superheated using a steel fork.
2. Reheat the water using microwave oven, and repeat the test.
3. Reheat the water using infrared ceramic stove until some bubbles are formed, and repeat the test.
4. Reheat the water using infrared ceramic stove until some bubbles are formed, and repeat the test.
5. Compare the results to determine if they are produced by the same phenomenon.

Now I've done editing and uploaded it.

Comparison with Infrared Stove

[alancalverd]

Nucleation doesn't only require a foreign particle. Nucleation by movement is often observed when supercooled water freezes as frost on a car roof. Microwave absorption does not depend on convection so is less likely to invoke boiling nucleation as the water is heated relatively uniformly throughout its bulk or even top-down, unlike a conventional cooker.