What Happens When a Liquid Turns Supercritical? 

I want to address a concern that people are mentioning about vapor pressure. When you put a liquid in a container that is bigger than the volume of the liquid, some of the liquid will form a vapor until the container reaches the vapor pressure of that liquid at that temperature. If it is a pure liquid (no air in the container) and all of the liquid doesn't evaporate, then the total pressure will be somewhere along the liquid/vapor line on the phase diagram. But, if there is air in the container, then the liquid will form a vapor and increase the pressure until the partial pressure of the vapor reaches the the point on the liquid/vapor line in the phase diagram. The point is that if you have a *pure* substance and you tell me the temperature and pressure of the container it is in, then I can tell you if it is a liquid, solid, vapor or gas. (Also note that if the temperature and pressure are on the solid/liquid/gas equilibrium lines on the phase diagram, then I can't tell you how much solid/liquid/gas you have unless you tell me how much energy you have input into the system and how much liquid you started with etc.)

The supercritical transition is still one of the coolest (heh) things I've ever seen. I've watched a lot of people using supercritical CO2 to make aerogel, and watching the meniscus just gradually disappear still blows my mind.

This channel has some of the most intuitive explanations (and demonstrations) of scientific concepts anywhere. I've said it before but for almost every video there's an "Oh! THAT'S how that works!" moment for me.

This is so cool, as a refrigeration tech I too have been curious of the phase change of supercritical fluids. Our entire industry is largely based supercritical and subcooled fluids to transfer heat and rely on pressure changes to affect said state.

I learn so much from this channel .. not only in terms of science but content creation as well .. so simple yet so baluable … amazing 🔥💯

You always bring us the most epic thought-provoking videos I have ever seen on RU-vid! I tip my hat to you Mr. Action Lab 🎩

I mean it when I say your videos are very hard to pass on. Every one I see available hooks me and reels me in like a fish lol. Arguably some of the most enlightening and entertaining content on RU-vid or anywhere else for that matter. You're a gifted teacher and I've learned a lot without having to try!

Fun fact: Xenon gas is used in headlight bulbs called "High intensity discharge bulbs" or HID. Electricity is used to ignite the gas and keep it at a stable temperature. The temperature of the gas once ignited determines the color of the light being projected. You can have anything from amber (lower temps), to bright white (slightly higher), to blue (slightly higher), and more.

This was a question I had in my mind for a long time but never got to search for an answer. This explanation is much more interesting than I expected!

I super appreciate your work and this channel. It often sorts out concept for me that have been rattling around in the back of my head for ages.

dude, your channel rocks. I;ve been repeatedly impressed with how you can tackle a highly complex topic with seemingly simple demonstrations. I've forwarded many videos to friends with "see, this is why this happens or works this way, etc"!

Probably the best (and simplest) way to explain the difference between vapour and gas.👍

Hi, James. This was awesome. I absolutely love studying supercritical fluids, and sublimation of solids to vapor. You have really come a long way with this channel. Good work.

Simply explained but still professionally. That’s why I love this dude

I believe what you said at 4:05 is not right...you should always talk about partial pressures - there is always some partial pressure of gaseous phase over liquid - the bold line in phase diagram just marks the point, when partial pressure of gas equal the surrounding pressure (in everyday life it is atmosferic pressure)

The cool thing is that as the supercritical fluid forms, the gas above and liquid below approach having the exact same refractive index, which is why the division between then becomes more and more difficult to discern.

This clarifies so much physics, I had no idea. Your videos always bring something new! I’m 29, and really interested in science, and yet, you never fail to drop new knowledge with every video!

Everytime!!! Always so impressive! And thank you for saying the difference between gas and vapor. You ended a very long (friendly) debate between myself and one of my classmates from decades ago! I was so happy to send him this! And always such a pleasure to see your excitement about teaching... Absolutely contagious! Keep it up friend! I'll be sure to check out whatever you've got up your sleeve for the next video! Yeah science!

I find you channel extremely fascinating!!! Even though sometimes I don’t understand anything, I think that makes it even more interesting in some strange way

I love this channel, I always learn new and interesting things

I have seen triple point labs but I have not seen the critical point before! This is really neat. Just seeing the meniscus disappear.

I once tried to make super critical liquid, but it said I was doing it wrong...

Great (and simple sounding) explanation for a very complicated process! Also love the visual demonstration with xenon gas! Great video, as always!

Hi! Great video! May I suggest something? Film it again having a diffuse light shining behind the vials. It can be a led behind a parchment paper. This will help visualize the phases as we do it in shadowsizing for two-phase flow.

Love your content and it's very educational

I'm always enjoying your videos, so interesting! But I wonder if you may forgot to mention something around 4:20. Because materials, especially liquids possess a property called vapour pressure, causing the transition to a gas well below the boiling point in oder to establish a equilibrium between gas and liquid phase. This is also one of the reasons one can nicely smell liquors so easily. I'm just curious if you left it out on purpose. Anyway, keep up the great work!!

Thank you. In university I had to deal with a number of phase diagrams and I never ceased to be amazed at how substances behave under different conditions of pressure and temperature.

This particular video is much nice. Please post more on this. Probably this could be a life saver for high school students interested in physical chemistry.

Whoa. That vial is pressurized to 60 bar? That's almost 900 PSI. I wouldn't dare touch it, let alone cool it, heat it, etc. I didn't know a little glass container could hold that much pressure. Living & learning.

Thanks for another great video! This reminds me when I was a sailor in a ship with a steam turbine for propulsion. We brought the feed water (very pure) up to 750 degrees at 550psi. This "dried" the water so that when it hit the turbine blades it didn't cause damage and was converted into a usable force. Fun stuff.

I like your videos a lot! Initially I did not enjoyed it but the quality of content and yor attitude conquered my heart and mind! Thank you very much for what you do!

I remember learning about the conversion graph in chemistry class. It is really cool to see it again.

I love seeing your videos, and trying to wrap my head around what I'm seeing, especially this. And I'm a little nervous that 60bar is being contained in that fragile-looking little ampule, I'd be afraid to handle it for fear it'll explode lol. One thing about water vapour though, I must mention, is that yes, even without air present, vapour still emerges off liquid water below 100°C. That's why it'll boil if you remove the air. There are a range of vapour pressures even below freezing, of course it's very low below freezingb(sublimation). Water will evaporate until there is equilibrium, then there is no net change of vapour/liquid and no boiling. This principle is used in heat pipes 👍

I love it. Where could I buy one of these to demonstrate this to my daughter? She's 9 and loves science! I looked online and didn't find much.

I knew all this stuff theoretically before. But in this vid I actually SAW the phenomenon for the first time! Thank you so much!

I learnt so much here because of your channel. As a science graduate i haven't learnt this much in my academics. Thanks to you.

Currently taking thermodynamics and having to get used to the steam tables was super difficult for me. This is cool to see it demonstrated. "compressed liq. Saturated Mix, Superheated, and Super critical states"

4:12 Well, if we had pure water surrounded by nothing but water vapor, extra water vapor would still come off of it. And the reason we see the vapor is because the partial pressure of the water vapor above the hot water greatly exceeds the vapor pressure that water would have at room temperature, and so the water vapor is at too high a pressure, and therefore condenses faster than it evaporates (the equilibrium is shifted towards condensation). And so this forms millions of tiny water droplets, which is visible.

Love your channel, never cease to surprise with some interesting and new

That was the coolest thing I've seen you demonstrate. Blew my mind. Like watching a mirage dissappear. So cool!

I’m guessing it grows a hair and beard, puts on a white tshirt, and gets a deeper voice along with a vernacular full of obscenities.

I really wonder what this would look like with food coloring introduced. Would it color the supercritical fluid, or would it just collect at the bottom, with a little bit of liquid that doesn't convert?

Best videos where you go straight to the point!

It's crazy to see the visual effects of a liquid more viscous than water. Thank you for bringing this to the internet so people like myself can have the experience of witnessing it in our lives!

I'm most surprised that little glass vessel can hold 60 atmospheres..that's almost 890 psi right?

This is great! More of these please!

Excellent. What is really tough for folks to understand is how we have learned that with exceptional high pressures we can now compress liquids and change their properrties.

Thank you for always allowing me to gain more knowledge.

Happy you come back to address the pressure issue. What you said in your video was correct of course but a little muddled for people who are not familiar with the subject. Another informative and fun vid.

I like the way you explain the chemistry.

I stumbled on to this channel a couple days ago. Now I'm hooked.

I want to thank you for the content and the excellent pronunciation, that helps a lot to non native English people

Just a quick MASSIVE thank you for putting your Short Videos on a separate channel. I wish more RU-vidrs would do this to keep my subscriptions from being overrun with Shorts.

Thanks for explaining the isolating the water part lol. That's got to be the most ignored part about that diagram that people just forget to teach it and cause a lot of confusion when solving vs seeing it

As a MSE undergrad, I've seen hundreds of phase diagrams in class, but never saw what a supercritical fluid actually looks like. As soon as I saw what was happening, it immediately became clear what was going on. Very cool!

Really enjoyed watching this and learning about the states. O love the way I can actually understand and he didn't make you feel stupid with his explanations.

im very interested in science and tech since i was a kid. i wish you have an animation in every thing that you say to be understandable easily because english is not my primary language and im a slow learner. more power to your channel

Gosh darn I love your videos, I almost always learn something completely new and amazing.

This one "mist"ified me. Seriously, I didn't expect to be so intrigued by this topic but I was fascinated. You never know what will grab you.

Wow - difficult to get your head around this - great stuff man.

This was one of your best videos. I'm a chemist, and as much as I've studied this stuff, supercritical states have always fascinated me, and you very rarely get to see them demonstrated so clearly.

nile red + you is the best combo for better understanding

It almost looks like a dissolve editing effect/transition. Just really cool

So cool to see this stuff happening in real life instead of learning through tables/graphs like at school.

Man I look forward to these !

This was very interesting I loved the phase chance disappearing act. amazed!

I like how excited he is about this and I appreciate that he shares this stuff with us

I always wondered about steaming cups and water vs vapor vs temperature. It's confusing! The water phase diagram is really cool, so many forms

Awesome! I learned something new today!!

Very awesome! thanks for posting! :D

This was a fantastically informative video!

Very well explained!

I love your videos! Can you explain and demonstrate triple point water?

This was very interesting. Another great video from you.

Nice video I was in IBM R&D Wets engineering had to explain to the operator's what was the process is. Video like this will help you with the explanation of process.

Love youre vids keep it up!

this is really cool. one of my favorite videos

I've only heard about these concepts. Watching a supercriticality for a first time.. Really worth it.. Thanks

So I've been familiar with the concept of phase diagrams for more than 20 years, but obviously didn't understand them. My mind was blown several times in that video!

Supercritical fluids are used to extract lots of good stuff from plants material such as coffee and hops (and that other plant closely related to hops). I have a video on my channel showing a Vitalis Q90 commercial extraction machine that uses 5000 psi pumps to get the fluid supercritical. Massive and truly facinating peice of technology made here in Canada.

We have a supercritical fluid extractor (S.F.E.) where I work. We use it to extract fat from liver powder and chlorophyll from alfalfa. The liver fat smells gross.

Love getting my mind blown everytime I watch a new video. The universe has so many secrets.

Thanks for a great video!

I never get tired of watching that.

this will be super cool to see this in slow motion with some high speed cameras !!

The world needs more people like him.

Thank you sir, this vid helped me a lot💐

I saw a video of a guy who makes water freeze, evaporate, and be liquid, all at the same time and it's amazing.

I learned so much here!

I think it’s cool that as the xenon approaches the critical point, the density of the vapor rises while the density of the liquid falls until they are equal with each other. That explains why the meniscus disappears the way that it does. The atoms in liquid phase and the atoms in vapor phase have no reason to stay separate so they just diffuse into each other. 3D phase diagrams are fascinating in that they also include density (or rather specific volume which is the inverse of density) along with temperature and pressure, showing how all three properties interact with each other.

Enjoyed that very much, Thank You : )

It would also be worth mentioning/showing the vapour dome (P-v diagram). Not only is it neat for showing the phase transition, but also other stuff like the almost incompressible nature of most liquids, and of course the supercritical point at the peak of the vapour dome, where there is no longer a distinct set of boundaries to cross between liquid and gas.

This is pretty cool. Can you do prompt critical next?

Nice info,thanks for sharing :)

Cody on Cody's Lab did this with a few different gases, so cool.

Wth bro! Its so freaking amazing first time seeing something like this. 💕👌

Nice video! I am running supercritical CO2 every working day! And I am still amazed by the diversity of possible applications!

Amazing. I've been wondering what compressed nitrogen would look like at room temperature. How to keep it liquid, contained, and see how it behaves. This is how my brain works. I love this channel!

I love your videos so much!

I really want super close up slow mo of the sloshing transition in supercritical! Maybe use that lighting effect that lets you see hot air coming out of people's mouths the schlaren effect or something...