When I was kid, I didn't think 100% humidity meant 100% water vapor, I actually thought it meant 100% water! So, you can imagine my confusion when humidity reached 95% and I didn't see any amount of water remotely near what I expected.

5:20 "Yay metric". Proceeds to do calculations in pounds per square inch and inches of mercury 😂

Just do it in meteric. On a nice 20°C day with 1030 hPa Atmospheric pressure water has a vapor pressure of 23,4hPa so it will boil at 10,066m. Much simpler.

I'm VP and past-president of the Astronomical League, an 18,500 member national federation of astronomy organizations in the U.S, and also a former ISEF judge. I have to say that your videos are just brilliantly produced but, more importantly, convey an enthusiasm for science that is completely infectious. I really want to commend you on your work with these videos. If you delve into any astronomy related projects, we'd love to have you speak at a convention sometime. We'll be in Albuquerque next year (doing virtual this August). I just subscribed to your channel and will recommend it to others..

this guy is like backyard scientist but not based on intuition

Great presentation. In scuba diving we were taught that one ATM (atmospheric pressure) is the equivalent of 33 ft of water. Therefore at a depth of 33 ft your total pressure has doubled, tripled at 66 ft, quadrupled at 99 ft etc. Your 396 inch hose height divided by 12 equals 33 ft.

1:43 Did anybody see a big obnoxious yellow-green arrow, instead of a green one?

Great video! You did a good job of accurately explaining things without giving inaccurate but broadly sort of correct explanations which drive me crazy coming from a chem engineering background (those things that aren't entirely wrong but just aren't really correct). Everything was spot on and easy to understand. I even learned some stuff which I wasn't expecting. One thing is point out when talking about the upside down bottle is that the bottle holds up the atmosphere above it, so water pushes up into it because in that area the atmospheric weight it held by the bottle.

This was a question set by a Physics teacher at school: "Superman has a fire to extinguish and a well 11m metres deep. He has a length of hose but he cannot suck water out of the well. Why?" The solution was demonstrated by the teacher hooking up a round-bottomed flask of water to a vacuum pump and we watched him hold it in his hand as the water boiled off.

"Basically one giant vacuum pump." "Oops, Gravity works!

When you say “I just boiled a litre of water”, it’s more correct to say that you boiled a fraction of that litre of water such that it produced a litre of steam. At 0.025bar I’m unsure what the density would be since I haven’t done thermos in a while, perhaps just 0.025mg/L? In that case you boiled only 25μg, or 0.025mL of water, which could be plausible. Calculating the temperature drop due to the enthalpy of evaporation would be a straightforward task. Makes you wonder how much of the gas in there was offgassing from the plastic. I can see why the gravity-based vacuum pumps use mercury instead of water!

Excellent video. Clear, concise, with a quick pace, and a high density of information. If all of your videos are like this, you deserve more viewers. Thanks for sharing. I actually posted this to another channel thinking it was you lol. Glad I found the real channel.

Awesome video. I'm an engineer that works with steam every day, and have never come across a video that captures so much of the fascinating nuance as this one does. Great work, earned my sub!

I was hoping you'd walk back down and re-condense the steam...

Thank you for this! I have heard of this thought experiment so many times, but I've never seen anyone actually do it. Very cool, and so simple.

This is a beautiful way to teach practical physics. Wonderful way of explaining.

4:12 Suction? I can hear my physics teacher from high school saying "Physics doesn't suck" as a response...

That looked like a lot of fun. I boiled water in an old dental syringe by making sure it was bubble free and filling it up about a third of the way when I was a kid. It fascinated me how I could simply plug the hole and pull back on the plunger to make it boil. This was a really cool scaled up, gravity powered version of that. It's also why water boils off so easily in the near complete vacuum of space. Nice video.🤘

I knew this. I studdied this for 4 years and i still got something out of it. And you spoke about boiling water. One of the most mondane tasks in this day and age. Hats off

The time and energy you put into this is really inspiring. I love the video!

As a cheap small scale alternative, you can simply use syringe. Remove needle, get 1/3rd of barrel with water, cover the hole with finger and then pull plunger for 2/3rds just before plunger pops out, and you'll see water boiling.

You can make warm water boil in a syringe by blocking the outlet hole and then pulling back on the plunger. I do it as a demonstration for my classes when I'm teaching about the effect of pressure on the boiling temperature of water and other liquids like refrigerants and bottled liquefied gases. Good video, many thanks. Toby

bro this video straight up inspired me to a line of inquiry that lead me to learn something new. Thank you so much for your time in creating this content. It helped me.

As soon as I saw the video title I knew exactly what you were doing but it was still amazing to actually watch you do it. I love physics! I'm sad I didn't find your channel sooner. Here's hoping my contributions to the algorithm bring you a few more subscribers.

In the future you might doing a follow up video using a syringe to boil water. Just place a partly filled syringe with a very thin needle under water and quickly withdraw plunger and you can boil water due to partial vacuum in barrel of syringe. Great video!

man, this would be soo much easier with metrics ;)

Thank you for explaining vapor pressure so well

Love listening to people who are smarter than me. Keep up the hard work, I hope you make a good living doing this

Additionally this is what causes there to be a limit on the height of most trees.

really fantastic video but I (and judging from some other people's comments, they as well) would appreciate the conversion of all units to metric (like psi into hPa or bar)

Awesome demonstration, and so well explained! Your videos are amazing

My dude. You showed the good stuff at the beginning, but you know the explanation is the great stuff.

"Ok so this is really exiting - I got a bucket of water under a stairwell with a hose sticking out of it" my brain at 4:30 am work in 2 hrs: *I'm listening*

That's by far the best explanation of gravity vacuum boil that I've seen. Could you try connecting two of these together and have one boiling the water, and condensing in the other? That would effectively be water desalination system with no moving parts. I think you just need a couple of degree celsius temperature difference between the boiling and condensing bottle, which could be done by painting one bottle black. Inspiration from Robert Murray-Smith ukposts.info/have/v-deo/rGaTZaOEkWeBu40.html

Frankly, you're the amalgamation of several interesting channels/presenters that I frequent. I will call this a big win for the UKposts algorithm. Subscription achievement unlocked.

Great job - always wondered about this, never had a clear understanding until now. Thanks

it took me way too long to realize that you didn't just add the arrow in post

This is fascinating! Could this method perhaps be used to distill water using only kinetic/gravitational energy? Like, set up a sufficiently tall column, feed in contaminated water, and collect the evaporation in a sort of large retort?

I never had a good understanding of what “inches of Mercury” or “inches of water” really meant. You literally made a lightbulb go off. Great video.

Great video Brian, will definitely use it in my physics classes!

There is a great rule saying that every 10m bellow the ocean there is additional 1atm of pressure. Guided by this, one can pretty quickly realize that you just need a 10m water column to overcome atmospheric pressure(it can change by a few centimetres depending on your elevation and weather). Go metric!

This reminds me of veritasium’s how can trees be so high.

My dad used a flagpole to run this demo for a science club at my elementary school. It took binoculars to read the result. He did it on why there's a maximum height for a siphon.

by the way, you're one of the very few youtubers who i care to and need to slow down video playback speed to fully appreciate every concept. most youtubers i speed up by 3x or more.

Great video ❤ I'm gonna say it... the explanation & maths is a hall of a lot easier in metric... you don't need to convert units 3 times... We don't even use inches of mercury, just Pa.

I've never seen a weather report mention inches of mercury, though I have a vague memory of it being mentioned in school as part of historic science. Atmospheric pressure is reported in hPa (hectopascals) outside USA!

been wanting to do that for years , top vid , deffo got to do it now , awesome

mind = blown. That was amazing explanations! And amazing experiment! Love to Physics !

Follow up experiment! How temperature dependent is it? Would adding ice cubes to the bottle and lowering the temperature of the water change the height by any significant amount?

And this ladies and gentlemen is why there's no liquid water on mars, or if there is, it doesn't last long, there's basically no atmosphere on mars so that huge column of air isn't there there to stop the water from just turning into a gas and escaping out into space.

You sir are an exceptional science communicator.

This is a completely wonderful demonstration!

Those nalgene bottles are tough, like I've taken a shovel to them tough. I'm surprised air pressure has that much force.

2:54 - this would be a spot where Jeremy Clarkson would say something like "sometimes my genius scares even myself"

Great vapor pressure visualization and explanation.

It's not all the time, but definitely here and there while you give your explanations I hear Bill Nye in the way you talk. The cadence and inflections and all.

I see you made this video some time ago but I just got clued into your channel. I like it! In regard to this demonstration, could this process be used to desalinate salt water? As I understand boiling salt water, the water is separated as steam, the steam rises to a collector of sorts and is allowed to return to as water without salt. There are different ways of desalinating water but everyone says it is energy intensive. Could your demonstration be applied for desalination? Curious Tek

Ha! I was wondering why the water bottle hadn't collapsed, then the ending!

You're really smart and I love watching your videos :) Makes me feel a lil smarter each video I finish ahah

Wow this channel is blowing up! I remember you were at 30k subs just a couple of weeks ago. Well done, and keep it up!

Nice demonstration about atmospheric pressure. Question, if you lower the bottle after its empty, is it refilled again by condensation? Would you be able to get "clouds" and rain inside the bottle? Keep it up!

Great video, but really wish people would just use the metric system.

pretty frikkin amazing!! you just don't realize how much there is to learn ...WOW

For more content like this allover the globe. Interesting physics, explained in a usual situation and teaching a plenty of stuff while. What i mean is: good quality work

Those Freedom units should be boiling and fading away aswell, regardless of the temperature

If you catch the vapour and condense it, would that be enough to get rid of bacteria?

This is a great video with clear explanation.

That experiment earned my puny little sub. Looking forward to more. Thank you!

Metric when doing calculations, especially with water, is so much easier than any other system. Really interesting video, always wanted to try this myself, but doing the calculation in pounds, inches, and mmHg is just mind numbingly confusing and unintuitive.

You didn't boil a liter. You boiled a miniscule amount, just enough to fill the void of one liter under very low pressure.

When I was a kid, I read about this in a textbook and really wanted to see it. I scoured the Internet for a video but couldn't find one. Then, a few years later, Veritasium came out with that video of a very long straw, and he showed it for a second. I could barely see it! Now we have videos like this one on the Internet, and also videos of water in a vacuum boiling and freezing at the same time due to channels like The Action Lab. Kids these days are so lucky to have all this at their fingertips. I'm 25.

man your intro is absolutely sick. its great every time.

You didn't boil one liter of water, you only boiled so much to get one liter of vapor ;)

“Im gonna go boil some eggs in water” does this but with an egg in it

you are a great teacher

Great example. But don’t forget, it still takes energy to change the liquid to vapor so the warmer it is outside, the faster it will boil. Also, many don’t realize that water won’t go over its boiling temperature, adding extra heat makes it boil faster but NOT get hotter. Excellent video.

8:47 fun note: Even as a solid, there is still some water "evaporating" from ice in the freezer. It's the whole process behind "freeze drying" CodysLab did a video about it: ukposts.info/have/v-deo/gZV2bJyopm2kkn0.html

11:39 “it’s brand new i bought it today” Lol universe doesn’t care

I've just learn, something new, something really important, thanks

Brilliant!

I love your videos, they are both interesting and meaningful. However it's a shame that you, as a scientist, don't use the SI-system.

Was it just me or was the green arrow yellow?

Very good video, very well explained. Thanks.

Great video, love all the details really good!

the whole boiling water at room tamperature thing gets more kinky, with a small amount in an insulating container. the rapid evaporation extracts a heat from it, untill the water freezes solid while still bubbling.

9:13 So.. you say... "A 100% humidity doesn't actually mean that all volume is water"? And that would not allow you to breath? Have you ever been to Florida?

As vaporization is the name for boilling water with heat, cavitation is the name for this physical phenomenon. Lots of cool stuff to see with this keyword. Nice video. A good experience to catch physics, one could add a pressure gauge on the bottle for the less faithful.

Thanks for details. Better explained than action labs.

It's always so weird when someone tries to do something technical in imperial 😝

How is it "room" temperature when you are outside? Check mate atheists!

We had a lab in high school where we did something similar, boiling water under a vacuum. The teacher set it up so we wouldnt expect the result. It was fun and clearly memorable.

I’m glad Steve Mould sent me to this channel. Great video!

REI= really expensive items, buy elsewhere like campmor and save a bundle

I think we need a new definition of the word "boil", because boiling to most people means "hot", which it doesn't, obviously.

Chemical engineer here commenting on the last min when he collapses the water bottle: this is something we constantly have to be aware of in manufacturing plants with metal tanks. They're designed to withstand alot of force pushing out from the inside but if you were to create a vacuum in the tank its pretty easy to collapse even a stainless steel tank because they're not designed to withstand that force

This channel is so under appreciated

Easily one of the best youtube channels

Now here is what is happening. Water molecules are polar, that means one end of the molecule is slightly positive while the other is slightly negative. This happens because Oxygen has a greater attraction for electrons that Hydrogen, so the electrons in the bond are pulled toward the Oxygen (the electron cloud is denser) giving that end of the molecule a slightly negative charge. The Hydrogen atoms are slightly positive because the electron cloud is shifted slightly toward the Oxygen and away from the Hydrogen. We call it Hydrogen Bonding, and it is a very weak attraction. What does that have to do with boiling water you ask. In liquid water, the molecules are attracted to each other because of the charge separation, Oxygen is attracted to Hydrogen, and Hydrogen to Oxygen. This attraction is the reason water has a high surface tension. It is also the reason that water is liquid at room temperature rather than gas which it would be if water was not polar. Water molecules have to have enough energy to break those weak Hydrogen bonds to escape the liquid. Boiling, as well as evaporation requires molecules have enough energy to break free from the liquid, i.e., overcome the electrical attraction AND force their way into the atmosphere where the air molecules are pushing against them. Heating water gives the molecules energy. Boiling occurs when they gain enough energy the break free from the surrounding molecules and force their way into the air. However, lowering the air pressure above the water removes the need for the molecules to force their way into the air. So that energy requirement is gone and molecules at room temperature have the energy to break free, voila we have boiling. It's like the difference between walking out of your classroom into an empty hall and having to push your way into a crowded hall during class change. Increasing the air pressure increases the energy needed for the molecules to force their way into the air which means the boiling point increases like it does in pressure cookers. your car's cooling system is also under pressure so that the water in it can be well above normal boiling point without boiling.

That is insane yet so simple

I distilled ethanol using the temperature difference of hot and cold water taps! Two vessels, one length of tubing, hot bucket, cold bucket. Both vessels went into hot bucket to get hotted up. One vessel had dirty solvent, the other vessel a little clean solvent. On heating, both vessels purged air due to vapor pressure of solvent. Don't have to get boiling, just hot enough to push out the air. Once purged of air, I connected tubing to the vessels, blocking outside air. The receiver vessel was placed in the cold bucket. Keeping the hot bucket hot and the cold bucket cold, the solvent 'moved over' to the receiver, leaving the contamination behind. If there is at least a 5-10 degree F difference between the hot and cold buckets (and a vacuum!), the still works very well. See also: Heat Pipes.