Does Water Really Boil in a Vacuum Chamber? And Why?

okay today I'm going to be talking about why water boils in a vacuum chamber so ever since I started doing this vacuum chamber stuff I would say the number one question I get is questions about the reason that liquids boil in a vacuum chamber so I want to address some of the main questions that I've seen about water boiling in a vacuum chamber why it boils what are the bubbles that you see what are the bubbles made out of and what's happening there so the first thing to understand about water boiling and you might know this if you've ever done any cooking you know that at different elevations that water boils at different temperatures so there's no set temperature that water boils at it depends on what pressure you're at so for example at sea level on the coast water is going to boil at about 100 degrees Celsius or 212 degrees Fahrenheit however if you're in Denver Colorado the water is going to boil at around 95 degrees Celsius or 203 degrees Fahrenheit and then if you're on top of Mount Everest water is going to boil it around 71 degrees Celsius or only 160 degrees Fahrenheit and the reason that's happening is because as you go higher and higher up the pressure gets less and less and less so the boiling temperature depends on what pressure you're at so the first thing to understand is we have to know what boiling even means boiling means when the liquid turns into a vapor so when this water turns into steam that means it's boiling so to show you what I mean I have some water in my vacuum chamber here I just dropped in some blue food coloring so that you can see the water easier it's kind of hard to see with a white background but I have a thermometer in here also it's a 30 degrees Celsius so it's just a little bit warm water around 85 degrees Fahrenheit so at sea level around where I'm at this water obviously isn't boiling but let's do the equivalent of lifting it up higher and higher and higher are taking it past Mount Everest and getting it up to where the atmosphere is very thin then water at 30 degrees Celsius will start to boil but before we do that let's talk about one thing you're going to see also is before it starts boiling you're going to see bubbles start to form and that's not actually the water turning into vapor but that is air that's dissolved in the liquid so air is actually dissolved in liquid water that's how fish breathe they breathe the air that's dissolved in the h2o so it's not water molecules breaking up but it's just air molecules so it's nitrogen and oxygen in there and those bubbles will start to dissolve out of it so you'll see little bubbles start to form but that's not when it's boiling I'll tell you when it starts to boil versus just seeing the salt air come out of it okay so let's take our water up to a very high elevation until it starts to boil okay water in a vacuum chamber boiling 3 2 1 we're at around 0.5 atmospheres not from Mount Everest type yet we're at around 0.7 our - we're on around point 3 atmosphere that's around the height of Mount Everest but this water on Mount Everest still wouldn't be boiling 29 degrees isn't hot enough to boil on Mount Everest but if we keep going higher up in elevation meaning lower and lower pressure then our water is gonna start to boil so you can see right now that there's bubbles starting to form in the water this is not the water boiling this is the air that was dissolved in the liquid now lower pressure it dissolves out of the liquid and back into atmosphere and so this is not boiling yet so you can see a lot of bubbles forming it's not boiling yet but a lot of bubbles are coming out of the liquid this shows you how much air was actually dissolved in this water this is just normal tap water that I got in my pack so this is the air that fish breathe normally we can't see it because it's we're at higher pressure and it keeps it in the liquid so now you can see as it starts to get more and more rapid that's probably not the air dissolving this dissolving out of the liquid that this is actually the water boiling so we're now at less than point one atmospheres way beyond the atmosphere at Mount Everest and you can see it's rapidly boiling now and the way that you can tell that this is actually liquid water turning into vapor meaning it's boiling is that it continually boiled if this were just dissolved air in the liquid then it would dissolve out all of the air that was in the liquid and then it would stop but you can see that this will just continually boil so another thing to remember is that when the water boils it's actually losing energy so it's getting colder you normally don't notice this like on your stovetop when you boil water you're continually adding heat so you don't notice that as the water boil that's cooling off because you're always adding enough heat so that it never stops boiling due to the temperature dropping but it when it's in a vacuum chamber and it starts boiling you're not continually adding a lot of heat so some of the chamber walls are just maybe at room temperature so as the water boils there's nothing adding a lot of heat to it still and so the water is actually going to cool down and that's kind of weird to think about you think of boiling is hot but really what you should think about is that boiling is just changing from a liquid to a vapor don't worry about it being hot and temperature and so I'll show you that with a smaller amount of liquid I'll show you that as it boiled it gets colder okay so I'm going to stick a thermometer in here so you can believe me about the temperature so right now it says it's at 19 degrees Celsius even though we'll be boiling it we'll keep reducing the temperature that's because the high energy molecules are leaving the liquid and it leaves just the low energy molecules and that cools the water so I have this pad under it that's just to insulate the liquid so that the heats when the chamber doesn't heat up the water okay we've been going about four minutes we're at fourteen point three degrees Celsius now and you can see that it's starting to boil there okay you can see that it's now boiling at twelve point five degrees Celsius okay we're at three point eight degrees Celsius only four degrees above freezing okay we're at one point nine degrees Celsius okay it's been like 25 or 30 minutes now we're a zero point seven degrees Celsius okay we drop to negative 0.1 degrees Celsius so this is a little bit lower than the freezing point atmospheric pressure hey thanks for watching I hope you learn something about boiling water and if you're not subscribed yet remember to hit that subscribe button and hit the bell if you want to be on the ball and see it right when it comes out and I'll see you next time

Channel: The Action Lab

Views: 411,516

Keywords: water, boil, bubbles, cold boiling, dissolved, gas, vapor, vacuum, vacuum chamber, the action lab, hydraulic press action, action, chamber, science, hydraulic press, arm in vacuum, fidget spinner, forever, fidget, spinner, boiling, cold, space, nasa, engineering, crush, destroy, fly, spider, ice, pressure, codyslab, grant thompson, king of random, air, no air, celsius, physics, physics girl, soliton, bubble ring, smoke ring, plate, pool, experiment, experiments, cool science, science experiment, math

Id: WTVwAZ0_9p0

Length: 8min 33sec (513 seconds)

Published: Fri May 05 2017