This Gas HEATS up when it should cool down 

Who can guess what happens to the outlet temperature of an ideal gas coming out of a valve?

This is one of the best discussions of the Joule-Thompson effect I've seen. Wonderful!

The gas isn't gasing

You are the best sciece RU-vidr, divulgative, you go straight to the point, you don't oversimplify, you don't take yourself too seriously and you always have things to surprise us

Chemical engineer here and this is one of the best explanations i have seen here. But all this can be totally changed when mixture of gases come into picture. I deal with hydrogen and even with above 50 mol% of hydrogen and rest being nitrogen and methane when you expand the gas mixture it cools. Thats different story

Even with arguably complicated topics you always manage to make the explanation clear and simple enough for anyone to understand. I can’t imagine how much work it takes to read the research papers full of technical jargon and “translate” them in a way that makes sense

The Joule Thompson expansion shows specifically how real gases are different from ideal. An ideal gas would not change temperature when undergoing free expansion, but real gases are sticky from van der waals. Except these rare exceptions. To be very explicit: refrigeration without phase change is only possible because of real gas being imperfect. Excellent video on thermal physics!

Never realized that gas expansion could be so complex and useful in medical procedures. Thanks for the deep dive into the topic, learned a lot.

You described Joule-Tomson coefficient better than my Physical Chemistry professor! Absolutely best science youtuber!

The visuals you added in this video is great.

Wow, it’s so nice seeing your video production continue to improve year after year with your popularity and success! I love seeing this channel grow 😁

This whole time I was thinking about duster cans as a way of applying this information. I'm glad you mentioned them at the end so I didn't come away with a false conclusion!

Your scientific explanation is superb. Never understood what the concept of enthalpy and learnt something interesting. Absolute gold!

I've watched many of your videos, I just want to say BRILLIANT, I don't always like each one of them but. You do a dam good job in your delivery on most everything I've seen. So.. thanks for your diligence and subject matter, I believe I'm learning great things to know. Peace.

I love the counterintuitive things. One time at CalTech a student in a lecture about hypersonic airflow said to the prof, "But that's counterintuitive". The professor said, "When it comes to hypersonic flow, you have no intuition."

It really shows the important impact of even the Slightest differences in a given environment. Temperature, density, pressure, charge, etc. Etc.

Wow! Saving this video to watch again to integrate full understanding. Thank you for teaching beyond Charles and Boyles laws.

the quality of the videos got so good

Yo i love the editing on this vid. Good job!

Awesome videos like always BUT i resently went on a marathon watching ur older videos and the ideas and things you tried were so cool it felt like i was kiddo again... Feel free to post any crazy videos thx!

this is the type of video i subscribed for. amazing video and always happy to learn something new.

Idk why but I am getting info about things right after or after sometime I study them in my classes. It has happened to me at least 10-12 times. Example my chemistry sir taught the states of matter and explained us ideal gas, real gas you have explained it a little better but as I have studied it so my info has been set in stone thanka

this is one of your harder videos to understand. great jobs explaining

this is probably (no pun intended) your coolest video yet!

This was really great. Thanks for the amazing content

Finally a clean explanation of the Joule-Thompson coefficient/effect.

Thank you, what an excellent video, clearly explaining the science with observations, and giving it a very real and useful practical example, these videos should be used in schools!

Brilliant video! One thing to improve on would have been to explain inversion temperature which you indirectly mentioned but would have been useful to go into it in a little bit of depth to fully explain the concept here. Thanks

Add longer fade-in / fade-out ramps to the mood music snippets to make it feel less jarring. Nice addition.

I never knew this was a thing! I like learning new things. Thank you.

Awesome, I learnt joule Thompson effect in chemistry, but helium and some other gases were exceptions. Good to see it practically.

It forgot how to gas.

Dang it, I keep learning stuff when I watch your channel!

excellent explanation of Joule-Thomson effect.

An excellent story, well told! I have been teaching ideal gas laws to students for over 10 years and this is going to help me teach real gases better. Thanks!

That was great, felt like I learned something today!

That's fascinating, thank you.

I love how you edit pauses just enough for me to mentally guess and then be like ohh yeah, that makes more sense when you explain shortly after asking a question.

Wow! This is super cool! I had no idea this was a thing!

I want more of these videos about things I actually have never heard about before, not the usual science facts that are covered by every other science channel over and over.

1. The Video quality improved a lot 💯 2. I was wondering why H,HeNe heated up instead of being cold (I was too lazy to read all these complex words in the text book for morethan a year ). Thank you for making a video on this topic.

Any chance you got the video idea from my recent post in ELI5 about the same topic and cryoablation? If you did, thats awesome! Glad you shared this amazing medical procedure.

Very informative! Also: Thank you for not using AI generated images for this video! (weird that I have say this, but most channels go the AI content farm route and it's depressing)

Never knew about the mechanism for Argon/Helium cryoablation, neat!

I’ve learned something! Very interesting and well explained.

i work for oil and gas industry and we use this a lot (really a lot, arround 120 tons/h). We use some light hidrocarbons (C2/C3) im the cicle compression-cooling-expansion for a few times to reach -100Cº, and the JT effect will help to isolate H2 from C1, 90% of all oil polimers (PP/PVC/ and many others) start to take shape with this.. so almost everything cool you have today make use of this phenomena. I knew how it worked , but never been able to fully explain it to new workers. Thanks to this video i am fully capable of

Thank you. I worked on ships in engine room. The exhaust gas from main engine has temperature sensors all along its path. I never understood why the temperature went up at 1 point as it expanded. Got it now

Every video lets me learn new things Thank you 💖.

New editing! New editing?! Nice! Its like a new season of the action lab, thats so cool hah

Always love your videos! Sometimes I play them at .25 speed. It makes you look like you’re drunk! I’m easily amused!!

Excellent video!

Thank you for this.

I was guessing Helium in the intro, and I got it right! My physics class is paying off, now I can properly pretend to be smart on the internet!

This one really blew my mind

Why wasn't this taught to me in school?! Thank u so much!

Excellent. Thank you.

Wow that was good I always thought that down to the atom the faster the vibrate the hotter they are and that's what makes heat so when you compress them it slows down the vibration and that makes them colder but how you show it I guess that isn't right. Thanks for your video. Good job.

This was so interesting to know.

Amazing! When some people ask why learning physics!

4:09 Slightly attracted to eachother, or repelled, with music from Carmen. Perfectly on point!

Very nice and well explained 👍

Learn something everyday..Very nice.

jesus, you went ham on the SFX this time.

Very interesting and useful.

Great topic

Cool video. One remark: the availalbe helium on earth is practically finite. We should use it accordingly for medicine, science,... and not waste it on bloons at parties and similar stuff.

Really good explained, you have definitely improved over the years.

Great video! My question is: why I have a physics degree and never heard about this effect???

Could you try performing the communicating vessels experiment inside the vacuum chamber as what keeps them aligned is the atmospheric pressure so this experiment would prove it and you could try involving other phenomena and properties related to that experiment

I wish professors could have explained that part of chemistry (physikalische chemie) in this manner to me back when I studied chemistry 20 years ago.

Physics is so dynamically complex. lol.. I love it

Now that was very interesting, I couldn't process why a gas would cool, my only thought was that in some way under certain pressures the gas may have more degrees of freedom, more places to store energy other than through movement (kinetic energy), and by releasing to the air you lower the degrees of freedom hence transferring that energy to kinetic energy.

Please make a detailed video on demonstration and explanation of the super cool phenomenon called "Sonoluminescence

Very interesting, but you don't need an exotic effect like this to cause localized heating and cooling of a spot. It could be done by alternating hot and cold flowing brine, or by electrical resistance heating combined with a cooling fluid, or by periodically reversing the current flow through one junction of a thermocouple. So this innovation in surgery is just a way to get a patent.

0:57 No, it just means you equalized the pressure between the 2 containers. The volume of 9g of air is the combined volume of both containers + tube. With the way you said this, you'd have to vacuum out the air from the smaller container instead of just connecting them with a tube. Edit: Quoting what he said: "Since I vacuum the air out of this [pointing at the *larger* ] container, if I just connect the two, then all of the air from this [touching the *smaller* ] container will now *mix between the two* ". The pressure in the system he made is equalized between BOTH containers connected by the tube. In order for the LARGER container to get all of the 9g of air, he'd have to use a vacuum device INSIDE the already vacuumed larger container to suck all of the air out of the smaller container to make the smaller container a vacuum now (aka no air).

Thanks!

Very Interesting...

My only note is that it might have been good to mention early on that temperature is a measure of the energy of the molecules giggling around.

I learned something!

I just had a cryogenic nerve ablation where they shot nitrous at nerves to create ice balls around nerve and ablate outer part of nerve, cutting off pain signal.

I love this channel

You could basically build a high school chemistry and physics curriculum with all of these videos!

If possible can you try an experiment that I came up with. The things you need are an empty room, a light source and you inside the room. What I have in mind is that , when the light source is turned on you are able to see the walls of the room because they reflect light from the light source. But what if we make the surface of the walls so imperfect that in whatever direction light may hit the wall it does not get reflected to atleast a single point in the room. Which means if you observe the room from that point, even if there is a light source in that room, you would not be able to see anything like the wall and the ceiling in the room.

This just made it more complex for me

Has the Joules Thompson coefficient ever been used in supernova calculations? I remember seeing something that scientists aren't sure how certain post-nova objects seem to gain heat the further away from the explosion source: could this possibly be explained away by such high temperatures that the pressure decrease increases the temperature? This one much more abstract: what if a similar coefficient could be applied to space-time and gravity, explaining potentially the dark matter or dark energy problem?

Yeaaaa… this may have been the least fascinating video I’ve seen from this channel. Which is STILL interesting.

Actually all matter has a definite volume, but that volume is always defined in relation to the environment it's in. Now the magnified effect of the environment is going to be greater on gas as opposed to solid, but the pressure in the surrounding environment is always going to be what defines that volume. If you change the temperature of any gas, liquid, or solid it will expand or contract accordingly. Thus changing its volume.

What a good video :)

INTERESTING 😊

Thanks for a great video...however I have some questions: @4.44 you say the "attractive forces are huge compared to the molecules".....if either nitrogen or helium is under placed under pressure in a confined volume, would it be true to say repulsive forces will exist between the gas molecules, causing them to want to move apart once released? Or put another way: when a gas is pressurized, on average, repulsive forces outweigh whatever attractive forces there might be. My second question: is the heating of helium local (at the throttle point), or does the entire system heat up (the bottle, the throttle and the discharged volume)?

Will the system under compression, entropy increases or decreases? Entropy is a measurement of randomness. Randomness can be anything among atoms from being different in atom's orientation or spin. Calling out a combination. If this is so then combination depends on temperature provoke by compression and expansion.

hey @TheActionLab, is this potential energy also responsible as to why supersonic flow speeds up in a (converging-)diverging nozzle?

looking smart sir

awesome

All gasses cool as they expand at lower temperatures and heat when they expand at high temperatures. The temperature where the gas switches from cooling to heating is called its Joule-Thomson inversion temperature. For hydrogen and helium, they are already above their J-T inversion temperature at room temperature so they heat up while all other gasses cool. The JT inversion temperature for nitrogen is 621 K or 348°C.

Does the Joule-Thompson Coeficient correlate with the speed of sound in the compressed gas?

I think it should have been better explained by radiation of photons/heat than kinetic energy of atoms. Surely those are related phenomena but we or thermometers mostly feel temperature of radiation and not kinetic energy of atoms. Most matter radiates heat through infrared spectrum. Anyway, I like your shows, thanks for good work. Cheers

Wow the day before my thermodynamics exam?

If you can’t experimentally tell the difference between two sentences and both work for predicting things, you can consider whatever you want as “truth”. That is what physical models are. They don’t care about what “is” or not true, they only care about propositions that help us predict things.

Please explore the Mpemba effect, please!!