Liquid Nitrogen and the Tea Kettle Mystery

Liquid Nitrogen and the Tea Kettle Mystery


Frostbite Theater presents… Cold Cuts! No baloney! Just science! Okay, it’s not that hot, not that cold. It’s sort of room temperature metal, so it’s kind of cool. Pretend I’m at home. I’m at home, my radio is broken. No music. The only music I can get is if this thing whistles, which isn’t that exciting but it’s better than nothing. How do I do that, at home? [Audience] Heat it up! Yeah, I go to the kitchen, I fill this up with water, put this on the stove and, for this to whistle, this has to get… [Audience] Hot! It’s got to get hot. Do I have a stove here? [Audience] No! No! Can I make this whistle? [Audience] Yes! How? [Someone in the Audience] Use the liquid nitrogen! Okay! Sure! We’ll try that! Instead of filling this up with water, I will put a few precisely measured and accurately delivered spoonfuls… Whoops… Of nitrogen into the tea kettle. So now, inside the tea kettle, I claim this thing is now 321 degrees below zero. Is that hot or cold? [Audience] It’s cold. Does it sound hot or cold? [Tea Kettle] — Whistling — [Audience] Hot! Hot! Yeah… Uh, right. Okay. I’m confused. Let’s take a vote. Who says “Tea kettle hot!” raise your hand. Who says “Tea kettle cold!” raise your hand. Who says “I’ve got not idea…” raise your hand. Okay, it’s perfectly fine not to know. That’s why scientists do experiments. They do experiments because they don’t always know the answers. So, easier question. What’s this? [Audience] A glove! A glove. I’m going to take the glove and wipe it on the tea kettle. What do you see on the glove? [Audience] Frost. Frost. Ice. This thing is cold enough we can take the water vapor from the air and we can freeze it to the surface of the tea kettle. Okay, so this thing is really, really cold. Can I have a volunteer please? To lick this. What’ll happen if you lick it? Yeah. What movie was that? That was Christmas Story? Yeah. So here’s what I’m going to do. Rather that have somebody lick it for real, getting the lawyers involved yet again, I’m going to take the glove, I’m going to carefully take a little bit of water from the flowers and pour a little bit of water on the glove. And clean up the little bit that I spilt. And I’ll carefully put the flowers back so they don’t get hurt. For those of you that have had literature, that’s called foreshadowing. Now, what we’ve just made is a model of your tongue. It’s wet and it’s floppy like your tongue is, it’s just blue with fingers, right, close enough. So, everyone who wanted to lick this, pretend this is you. Okay, so here you come to the tea kettle going ‘La, la, la, la, la, la.’ Everyone go ‘La, la, la, la, la, la.’ [Audience] La, la, la, la, la, la. And you lick the tea kettle. Now, that’s going to be fun for, like, two seconds. And then, you’re going to want to get your tongue back. So, what do you need to do? You gotta pull it. [Audience] Ow! So there is ice on your tongue. Here are little bits of tongue on the tea kettle. So, not a great thing to go around and lick. But, there’s a problem. You guys told me this whistles when it’s hot. Why was it whistling if it was cold? Yeah, how does a tea kettle work? It doesn’t work if something’s hot. If I’m at home, I’m at home, this is full of water, it’s on the stove, it’s whistling, what’s that mean the water inside’s doing? [Someone in the Audience] Boiling! Boiling! When a liquid boils it changes from a liquid to… [Audience] Gas! A gas! The gas takes up more room, comes out of the hole, makes this thing whistle. Tea kettles don’t tell you if something’s hot or cold. They tell you if something is boiling or not. So, if I take the nitrogen and shove it in here and it whistles, what does it mean the nitrogen’s doing? [Audience] Boiling! It’s boiling! It just happens that it boils if it ever gets warmer than 321 degrees below zero. What in the room is warmer than 321 degrees below zero? [Audience] Everything! Everything! Everything in the room is about 400 degrees too hot for this stuff to stick around. So, if the nitrogen touches anything in the room, it boils, changes back to a gas, goes into the air and we end up breathing the stuff. Have you ever taken water and flicked it on a hot frying pan? And the water kind of dances around? Does the same thing on the table. When we pour it on the table, it hits the table, it boils, and then it floats on a little layer of gas. So the table’s not wet. And if I want to get rid of the nitrogen faster than having it roll off, I just introduce it to mister glove. And I can boil it off a lot faster that way. This is what the stuff looks like. It looks a little like Sprite. I wouldn’t go drinking it. Why is it bubbling? [Audience] It’s boiling! It’s boiling! The air around it is 400 degrees too hot for it to stick around. If I touch it with my glove, it’ll boil faster. Don’t know if you can see that or not… If I put it on the overhead and Mr. Dave hits the lights… So, that’s what it looks like. It looks kind of like boiling water. It acts kind of like boiling water. But it’s not boiling water. It is boiling. Lights please. But boiling doesn’t mean hot. Boiling doesn’t mean cold. Boiling just means you’re changing from a liquid into a gas. Now, keeping in mind that this stuff is very cold, even though it’s boiling, I’m going to need from the audience, two somewhat brave and slightly foolish volunteers!

100 thoughts on “Liquid Nitrogen and the Tea Kettle Mystery

  1. The rest of the world can watch if it likes. However, the rest of the world shouldn't get its collective pants in a bunch when U.S. customary units are used with a U.S. audience. True, metric is the most common measurement system. It's also true that Mandarin is the most common language. That doesn't mean that it should be used for this presentation.

  2. Lol well I mean it's not like every country except America speaks mandarin as their native language… and even real American scientists use the metric system.

  3. Metric system, however, is one of the International Units, like grams. International units are the standard unit for science subjects. I'm not saying that the whole U.S. country should change it's measuring system (although that would be quite convenient), nor that the teacher should do presentations using metric system, but it would be nice to get the students accostumed to the metric system since it will probably be the one used in school exercises

  4. The audience wasn't filled with real American scientists. No point in doing something if the audience isn't going to understand it.

  5. I understand where you're coming from, but I mean why perpetuate a nonsensical system that the public should stop using in the first place? Like for example you could say "this is X degrees Celcius, or about Y degrees Fahrenheit" to at least get people thinking in terms of system that actually makes sense, rather than perpetuating a useless one.

  6. is this whole presentation in your videos? can i watch it from the beginning to the end in one video? or i have to watch it in episodes?

  7. No, the whole presentation isn't on YouTube. The other segments that have been uploaded are called "Should a person touch 200,000 Volts?" and "Liquid Nitrogen and Fire!"

    Other segments may also make their way up.

  8. why go to other place if our class rom is here in youtube 🙂 , is the same to be there or watch it here, the only no big deal problem is that we learn in parts :).

    thanx JeffersonLab teachers 🙂

  9. yeah, seen them. Is there any chance you upload the entire presentation some time? It would be nice to watch it all the way through.

  10. Not likely. Most of the missing sections are already covered in the 'standard' Frostbite Theater series. There's also a nearly complete liquid nitrogen show from one of our Open Houses up here ('Liquid Nitrogen Show!', I think) that would basically be repeated if this presentation were wholly uploaded. There's a section on plasmas and a beginning electrostatics section that may eventually get uploaded. If that's done, only the general Lab overview would be missing.

  11. Oh dear, not with this debate again. Anyway, I'm generally in the arts and not much in the sciences but I get interested once in a while. I may drop by Fermilab sometime.

  12. Nonsensical? You meant "unpopular". So long as measurement is done accurately and consistently, it does not matter what system is used in science. What if the advanced aliens across the galaxy who find us are using another system? Should they change to metric?

  13. you have to love the ignorance of people in general hah. americans speaking english and talking in Fahrenheit how dare they.

  14. …. O.o I'm a touch surprised that the glass on the overhead didn't shatter from a thermal shock when he put the glass on it.

  15. I sort of did this with a freezer before… I put the bottom of my tongue on the shelf and it got stuck, I didn't have the common sense to put water and therefore forcefully pulled my tongue of the shelf… I couldn't eat right for two weeks…

  16. Isn't liquid nitrogen expensive?
    And isn't it a bit dangerous to excessively boil nitrogen around you? – oxygen deprivation etc. ?

  17. For us, liquid nitrogen costs about $1 a gallon. Whether or not you consider than to be expensive depends on your financial situation, to which I am not privy.

    Yes, boiling too much nitrogen in an area can result in what's known as Oxygen Deficiency Hazard. What's used in this demo is nowhere remotely close to being enough to cause a problem. (It's generally considered bad form to asphyxiate your audience.)

  18. Sorry, I forgot to mention – great video as always!
    – And thank you for your reply 🙂 [here in Europe it's quite hard to find Liquid Nitrogen and also it's quite expensive – 5 euros/liter – about 25 US dollars/gallon]

  19. How much would it take for it to be a hazard in a room that large? (if it was all dumped across the floor at once)

  20. Something like 75 liters. That's ridiculously large when you realize that the Dewar we normally fill for a show is 10 liters.

  21. Thank you for the reply, from now on i'll know to keep my liquid nitrogen below 70 liters when i go to large conference rooms.

  22. Wish i could attend these talks…or i guess teachings. Even though i knew why it boiled.. its so interesting to see someone demonstrate it like this with this kind of passion and knowledge.

  23. This really isn't that interesting, the whistle on a kettle doesn't need heat to make noise, it's like a harmonica it just needs enough moving air, and clearly nitrogen expands when it heats up, just like water except more rapid, causing the kettle to whistle from escaping gas. The gas makes the whistle, the only thing heat affects is the nitrogen

  24. This is a school thing right? Why couldn't my schools have taken me to these? lol He should do these as a public thing to go to. Maybe he does and I don't know. I'm not sure.

  25. I have worked as a ski lift operator. One day I was working the top shack while the kid's ski team was exclusively using that lift. This is a very laid back job because being on the ski team these kid's all know how to get on and off a ski lift without any issues… Or so I thought. At one point I saw two kids coming up. One had his face very close to the bar that holds the chair on the lift while his "friend" was waving and yelling frantically. Being somewhat familiar with the behavior of both young boys AND cold metal I figured out, before they got there, what had happened.
      Of course one boy dared the other to lick the pole, which of course the other did. I was able to quickly and painlessly remove the kid from the pole with a bit of water. But I made sure the kid was very embarrassed. I made sure the bottom guy told EVERYBODY what had happened!
      It really was very funny.

  26. So was he talking about the Leiden Frost effect when he was saying that it dances around on the table?

  27. i guessed that at the start of the video (and i also never had heard about this problem), do i get a star and a happy face?

  28. It is quite interesting. It shows some forces/principals in action. The molecules diffuse from an area of H-L concentration (represented as pressure). It shows the leidenfrost effect and it also i some ways shows le chataleirs principal (unsure on the spelling as its been a while since i done science at school)

  29. what pressure would be needed to keep the liquid nitrogen a liquid inside a closed cell container?

  30. It is very nice of you to give the children such a practical approach to concepts of science congrats and please continue to do this

  31. It costs about 150 bucks for a gallon of liquid Nitrogen. He must make it himself or is a millionaire to spill it like that

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