[hamdani yusuf (OP)]

What is the current explanation on superheated water by microwave?

Is this superheated water in atmospheric pressure achievable using other heating methods, such as mechanical heating, induction heating, electric heating, magnetic heating, infrared radiation, etc?

[evan_au]

Superheated water can be produced in pure water, in clean vessels without nucleation sites, and as long as it is not too agitated.
- So mechanical heating/stirring would not be a good way to do it
- Pure water is not very magnetic, so magnetic heating would not work so well
- Pure water is not very conductive, so heating by electric conduction would not work so well
- Inductive heating of a clean metal vessel could work
- Infra-red radiation (eg inside an oven) would work well

[Hayseed]

Try distilled water, smooth container and a big magnifying glass.

Edit:  and a hot humid, calm day.

[Bored chemist]

You can demonstrate superheated water with a  candle and a test tube.
There's nothing mysterious about microwaves here- except people often use them to heat water in ceramic mugs with nice smooth surfaces.

[hamdani yusuf (OP)]

Superheated water can be produced in pure water, in clean vessels without nucleation sites, and as long as it is not too agitated.
- So mechanical heating/stirring would not be a good way to do it
- Pure water is not very magnetic, so magnetic heating would not work so well
- Pure water is not very conductive, so heating by electric conduction would not work so well
- Inductive heating of a clean metal vessel could work
- Infra-red radiation (eg inside an oven) would work well

The information I gathered around this problem doesn't indicate the use of pure water.

The water can be regular drinking water but should not
contain many undissolved particles. It can be heated in any
domestic microwave oven; a research-grade microwave oven
such as used by Kennedy (1) to determine the enthalpy of
vaporization of liquids is unnecessary here. The recommended
heating vessel is a glass teapot sold to be used in the microwave
oven (no metal parts). Using such a teapot generally has several
advantages: its walls have relatively few nucleation
sites for bubble formation, yet enough to put a reasonable
limit on superheating; it has a plastic lid to prevent boiling
water from splashing out of it; and it has a plastic handle so
that it can easily be removed from the microwave oven once the
water is boiling.

Erné, B.H. & Snetsinger, P. (2000). Thermodynamics of water superheated in the microwave oven. Journal of Chemical Education
77(10), 1309-1310. doi: 10.1021/ed077p1309

And this is a comment by someone who can reproduce the phenomenon reliably.

Steven Spielman, PhD in Applied Physics; optical properties of solids
Updated Mar 4, 2019
I was able to accomplish superheating without much effort. I heated water in a small glass bowl, in a microwave oven. Before it reached boiling, tiny air bubbles adhered to the glass, the result of dissolved gases coming out of solution. When the boiling point was reached, (presuming here) water vapor entered these bubbles without bound and they grew quickly. The water boiled normally.

I shut off the microwave for a few seconds, and the boiling stopped. Then I turned it on again. The dissolved gases have already been driven out of the water, so there would have been no air bubbles to get things started. The water just sat there quietly for 10 seconds or so. Then there was a “PUNF!” sound. I opened the oven to find the bowl mostly empty and the walls and ceiling wet.

So, to avoid it, don’t microwave water (including coffee, etc.) which has recently boiled. Keep your face away when you first disturb it with a spoon or sugar.

https://www.quora.com/How-likely-and-how-dangerous-is-superheated-water-in-a-microwave-oven-and-what-everyday-precautions-should-be-used-to-avoid-injury

[hamdani yusuf (OP)]

You can demonstrate superheated water with a  candle and a test tube.
There's nothing mysterious about microwaves here- except people often use them to heat water in ceramic mugs with nice smooth surfaces.

Do you have reference for this? Or have you experimented yourself?
What are minimum conditions to produce it?

[hamdani yusuf (OP)]

This phenomenon becomes my concern due to the danger such as shown in these reports.

A 26-year old man decided to have a cup of coffee. He took a cup of water and put it in the microwave to heat it up (something that he had done numerous times before). I am not sure how long he set the timer for, but he wanted to bring the water to a boil. When the timer shut the oven off, he removed the cup from the oven. As he looked into the cup, he noted that the water was not boiling, but suddenly the water in the cup “blew up” into his face. The cup remained intact until he threw it out of his hand, but all the water had flown out into his face due to the build up of energy. His whole face is blistered and he has 1st and 2nd degree burns to his face which may leave scarring.He also may have lost partial sight in his left eye. While at the hospital, the doctor who was attending to him stated that this is a fairly common occurrence and water (alone) should never be heated in a microwave oven. If water is heated in this manner, something should be placed in the cup to diffuse the energy such as a wooden stir stick, tea bag, etc., (nothing metal).It is however a much safer choice to boil the water in a tea kettle.General Electric’s Response:Thanks for contacting us, I will be happy to assist you. The e-mail that you received is correct. Microwaved water and other liquids do not always bubble when they reach the boiling point. They can actually get superheated and not bubble at all. The superheated liquid will bubble up out of the cup when it is moved or when something like a spoon or tea bag is put into it.To! prevent this from happening and causing injury, do not heat any liqui d for more than two minutes per cup. After heating, let the cup stand in the microwave for thirty seconds! before moving it or adding anything into it.
Here is what our local science teacher had to say on the matter: “Thanks for the microwave warning. I have seen this happen before. It is caused by a phenomenon known as super heating. It can occur anytime water is heated and will particularly occur if the vessel that the water is heated in is new, or when heating a small amount of water (less than half a cup).

What happens is that the water heats faster than the vapor bubbles can form. If the cup is very new then it is unlikely to have small surface scratches inside it that provide a place for the bubbles to form. As the bubbles cannot form and release some of the heat has built up, the liquid does not boil, and the liquid continues to heat up well past its boiling point.

What then usually happens is that the liquid is bumped or jarred, which is just eno! ugh of a shock to cause the bubbles to rapidly form and expel the hot liquid. The rapid formation of bubbles is also why a carbonated beverage spews when opened after having been shaken.”

America’s FDA has also warned about the issue, noting on its website:

The FDA has received reports of serious skin burns or scalding injuries around people’s hands and faces as a result of hot water erupting out of a cup after it had been over-heated in a microwave oven. Over-heating of water in a cup can result in superheated water (past its boiling temperature) without appearing to boil.

This type of phenomena occurs if water is heated in a clean cup. If foreign materials such as instant coffee or sugar are added before heating, the risk is greatly reduced. If superheating has occurred, a slight disturbance or movement such as picking up the cup, or pouring in a spoon full of instant coffee, may result in a violent eruption with the boiling water exploding out of the cup.

In spite of these factors, microwave users would certainly do well to heed the advice in the email. Hoax-Slayer visitor Al Chang relates the following experience illustrating just how dangerous superheating can be:

 

This just happened to me. I have a very smooth two-layer plastic tumbler. Imagine a cup suspended within a cup, so there’s an air pocket between the two cups. It’s designed to keep heat or cold from transferring from the inner surface to the outer surface.

I’ve heated water in it in the microwave before. There’s a certain amount of time around 2m50sec where it goes from being completely still to boiling over. Normally, I just keep it below that time and it’s fine. Up until today my only concern was the water itself boiling over while in the microwave.

Today, it must have been just under that time, because though it was still water, I took it out of the microwave, jiggled it a little and boom the water exploded all over my arms and hands. Very nasty scald. I suspect I could duplicate this consistently (which I might try under more controlled conditions once I heal up). It goes straight from still water with the tiniest of bubbles to overflowing in the microwave. I suspect it has a lot to do with the cup. Perhaps because there’s no way to transfer heat to the outside world other than the top of the water and the stillness keeps bubbles from forming. Movement then triggers the explosion. I have some first and second degree burns to show for it. I was lucky I was right near the sink and was able to get to cold water right away.

So word of warning to your readers!

https://www.hoax-slayer.net/true-circulated-warning-claims-superheated-water-microwave-can-explode/

The next victim could be one of our family, so we better make them informed. The correct explanation is needed to reliably, effectively, and efficiently prevent accidents. Until then, it is better to play safe and take preemptive actions although they may not really necessary.

[Bored chemist]

You can demonstrate superheated water with a  candle and a test tube.
There's nothing mysterious about microwaves here- except people often use them to heat water in ceramic mugs with nice smooth surfaces.

Do you have reference for this? Or have you experimented yourself?
What are minimum conditions to produce it?

How have you come to the conclusion that it is a rare phenomenon?
It's so commonplace that there's a wiki page about it.
https://en.wikipedia.org/wiki/Bumping_(chemistry)

Yes, I have done it.

"What are minimum conditions to produce it?"
As I said;
"You can demonstrate superheated water with a  candle and a test tube." (and water, of course- the candle has to be burning).

[Bored chemist]

The correct explanation is needed to reliably, effectively, and efficiently prevent accidents.

Not really.
Just learn to put the coffee or tea in the water, before you heat it.

[hamdani yusuf (OP)]

You can demonstrate superheated water with a  candle and a test tube.
There's nothing mysterious about microwaves here- except people often use them to heat water in ceramic mugs with nice smooth surfaces.

Do you have reference for this? Or have you experimented yourself?
What are minimum conditions to produce it?

How have you come to the conclusion that it is a rare phenomenon?
It's so commonplace that there's a wiki page about it.
https://en.wikipedia.org/wiki/Bumping_(chemistry)

Here are the specific conditions lead to bumping.

Bumping occurs when a liquid is heated or has its pressure reduced very rapidly, typically in smooth, clean glassware. The hardest part of bubble formation is the formation of the small bubble; once a bubble has formed, it can grow quickly. Because the liquid is typically above its boiling point, when the liquid finally starts to boil, a large vapor bubble is formed that pushes the liquid out of the test tube, typically at high speed. This rapid expulsion of boiling liquid poses a serious hazard to others and oneself in the lab. Furthermore, if a liquid is boiled and cooled back down, the chance of bumping increases on each subsequent boil, because each heating cycle progressively de-gasses the liquid, reducing the number of remaining nucleation sites.

https://en.wikipedia.org/wiki/Bumping_(chemistry)
I boiled water numerous times without ever experienced a bumping.

Even in the case of microwave, it is not as common as normally boiling water, otherwise it won't become a myth worth busted in myth buster.
Furthermore, below statement is found in the conclusion of this article: https://digitalcommons.sacredheart.edu/cgi/viewcontent.cgi?referer=https://www.google.com/&httpsredir=1&article=1063&context=chem_fac

It shows why, for safety reasons, precautions
are taken to prevent superheating in the laboratory, where
smooth-walled glass vessels are generally used; in the kitchen,
such precautions are unnecessary, since cooking pans and their
contents are sufficiently (micro)rough that superheating is
seldom a problem.

[hamdani yusuf (OP)]

While searching for references, I found this interesting video showing superheated water without microwave.

Here is the description by the uploader.

First I put some water into the pot. Then I started the stove and set its power to the maximum level. Ten or twelve minutes later the water was not boiling and there were not bubbles at the bottom of the pot. I thought that something strange was happening and it came to my mind the superheating phenomenon, so I took my videocamera and started recording. In the next seven minutes there were no changes (no boiling, no bubbles) so I decided to hit the objects in order to make small vibrations, but the water remained the same. Finally I hit the pot directly and suddenly the water started boiling. I was cooking when I recorded this video. I don't know how I superheated the water, sorry.

And further description in the comment section.

1) The pot was on a student hall of residence where I lived for one year. I think that it was not a new pot...
2) I cleaned that pot with a normal sponge, without any special care...
3) I did not use tap water that day, I used bottled water (I always use bottled water for some recipes)
4) Yes, it was a electrical stove
5) Yes, I have tried to reproduce it many times, but I did not get any results...

And another comment from a viewer.

You got lucky!  This just happened to me, but it exploded so powerfully that there was water on my ceiling on the other side of the kitchen!  The craziest thing is that it was tap water.   I put water on the stove to make some tea an took a shower.  I came out and it wasn't boiling so I was like WTF.  Just me bumping the stove caused the explosion.  I got a little burned on my arm, but I'm lucky considering how powerful the explosion was.  Only a few ounces left in the pot after the boom!!!

[hamdani yusuf (OP)]

I have also tried to reproduce the superheated water using microwave. For a start, I used commercial bottled drinking water which is readily available.  To limit the danger, I used a small quantity of water in a small smooth glass container.
I repeatedly start the microwave until the water boiled, but it never get superheated. May be next time I'll try to use distilled water.
I'll try to explore if there are limiting conditions to reproduce the superheated water, such as ion content, dissolved gas content, volume/surface area ratio, heating time, heating power, etc.

[hamdani yusuf (OP)]

The correct explanation is needed to reliably, effectively, and efficiently prevent accidents.

Not really.
Just learn to put the coffee or tea in the water, before you heat it.

It can't be done if you have to prepare hot water for several people who haven't decided what kind of drink they want. It's also possible that they just want to have hot water.

[Bored chemist]

Use a kettle.

[alancalverd]

The trick is to rid the water of nucleation centers. Bottled drinking water is no "purer" than the stuff that comes out of a tap - indeed whilst some mineral waters claim to be good for you because they contain no solutes, others claim exactly the opposite. But they all contain dissolved air (ask any fish!) and as pointed out in one of the above quotes, this can nucleate boiling. So you can maximise the chance of superheating by filtering (to remove solid nuclei) and degassing - slow heating with a little agitation, followed by cooling with no agitation.

There is a secondary consideration when using glazed pottery (coffee mugs). Salt glaze is quite conductive and some earthenware contains a fair bit of iron, so the pot actually gets hotter than the water inside it. If you bring the water quickly up to 99 deg C the pot may be at 110, so when you turn the microwaves off, the pot heats the water. For true superheating you need a smooth nonconductive vessel like laboratory glass.

[hamdani yusuf (OP)]

The trick is to rid the water of nucleation centers. Bottled drinking water is no "purer" than the stuff that comes out of a tap - indeed whilst some mineral waters claim to be good for you because they contain no solutes, others claim exactly the opposite. But they all contain dissolved air (ask any fish!) and as pointed out in one of the above quotes, this can nucleate boiling. So you can maximise the chance of superheating by filtering (to remove solid nuclei) and degassing - slow heating with a little agitation, followed by cooling with no agitation.

There is a secondary consideration when using glazed pottery (coffee mugs). Salt glaze is quite conductive and some earthenware contains a fair bit of iron, so the pot actually gets hotter than the water inside it. If you bring the water quickly up to 99 deg C the pot may be at 110, so when you turn the microwaves off, the pot heats the water. For true superheating you need a smooth nonconductive vessel like laboratory glass.

In my own experiment,  the water was boiled several times,  thus dissolved air should be already removed after the first boil. I used a clear glass with smooth surface.

[hamdani yusuf (OP)]

I found another video showing superheated water by microwave. Here the container is made of styrofoam.

Here we can see some bubbles are already formed on the container's surface even before the sugar is added. Thus nucleation site hypothesis is discredited by this video, and we need to find better explanation.

[Bored chemist]

I found another video showing superheated water by microwave. Here the container is made of styrofoam.

Here we can see some bubbles are already formed on the container's surface even before the sugar is added. Thus nucleation site hypothesis is discredited by this video, and we need to find better explanation.

It is remarkable what you can do with a bit of dishonesty, some vinegar ands some bicarbonate of soda in a sugar packet. (and a teabag).

[vhfpmr]

You can demonstrate superheated water with a  candle and a test tube.

The chemistry teacher used to give us pieces of porous pot to put in Pyrex beakers "to make the water boil more easily".

[vhfpmr]

The information I gathered around this problem doesn't indicate the use of pure water.

It doesn't even need to be water at all, I once successfully re-decorated the kitchen with an egg.