Boiling cold water In a Vacuum Chamber
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- เผยแพร่เมื่อ 16 ต.ค. 2013
- Cold water about 23 degree Celsius water is placed in a vacuum chamber and boils when the pressure in the chamber approximates the vapor pressure. I placed a thermometer inside the chamber and observed a decrease in temperature as it boils.
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I teach fluid power/hydraulics in college, and refer to this common high school physics lesson when we talk about pump cavitation. Shamefully, it appears the high school curriculum in our province no longer delivers this as none of them ever know what I'm talking about. Important lesson for HVAC training too. Thanks for laying a solid foundation.
Thanks for your feedback. Its good to know that I am pointing them in right direction.
Actually you arent. Youre claiming waters "boiling point" decreases under a vacuum, when that isnt the case. The water isnt "boiling" due to temperature factors, its due to there being gases present in the water. Marshmallows expand in a vacuum because of the air trapped in the pores, however, marshmallows do not "boil" due to lower "boiling points". This is a poor theory and shouldnt be taught to students as "fact".
Nicholas Driver can you please tell me if boiling water in a vacuum creates steam ? Honest question !
@@nicholasdriver6624 Wrong: De-ionized and de-gassed water does *exactly* the same thing - boils off.
Or, if you run the experiment through to completion, all the water disappears. If it wasn't boiling off, where did the water go then?
The boiling point of all materials depends heavily on the ambient pressure - which is why *all* boiling points are specified at a given pressure. If you think otherwise, you have an uphill battle against mountains of evidence and more than a century of materials science.
Furthermore, if you increase the pressure, the boiling point goes *up*. How does that work then?
@@nicholasdriver6624 You can be proven completely wrong simply by looking at a phase diagram of water.
So... the water is boiling but not hot... it does not add up in my brain.... I still won't touch it.
Yea buddy i hear ya, and in every demonstration i have seen they say "boiling" but the thermomiter does not say 100 Degrees, so its not boiling but bubbling i would call it
Great demonstration. Thanks for the education!
You're Welcome!
Wow! I be seen this before but now I m seeing it for what it is. You have demonstrated that we live in an enclosed system.
The cooling is because every mole of water that evaporates removes one molar latent heat of vaporisation.
The latent heat of vaporisation is not pressure dependant, or at least is only very slightly pressure dependant, so the evaporation cools the water to zero Centigrade then freezes it.
This is a good method for making sweet water from sea water
Thanks a lot for this simple video, God Bless
Can you explain how the water boiled despite being below its boiling point using vapor pressure, intermolecular forces, atmospheric pressure? If so that would be great!!!
"The water is loosing the molecules that are moving the fastest" WOW that is the best explanation for the process I've heard yet! Thanks!
How energy efficient is this compared to baking filament?
Can you explain how the water boiled despite being below its boiling point using vapor pressure, intermolecular forces, atmospheric pressure? If so that would be great!!!
@@yimszy4588 I'm not a physicist but look up "Vapor pressure" on wikipedia. Basically there is an equilibrium with warm (=fast moving) water molecules shooting out of the water and water molecules shooting into the water. If you decrease athmospheric pressure you have less molecules per area of air which means more can shoot out and bounce around in the air.
The intermolecular attractions I don't know, but they want to stick together but if too hot / fast they fly off.
@@yimszy4588 just imagine the surface of water. at 23*C, air pushes it's surface by 1 atm. but like in this video, we reduced the 1 atm on the water surface to 0 atm( nearly). Due to this the pressure at water surface would also become 0 (nearly). Then water would expand due to this.( at constant temperature, PV = constant. pressure is reduced, so volume would increase) expansion would reduce the inter molecular force of attraction which would seperate them and they would become invisible making them behave like gases.
Now you would say why scientists have two terms for a same thing i.e steam and water vapor.
the major difference between them is that vapor still has same energy as the water but steam has very high energy.
that means if you touch a water vaporise at STP, you will not get burnt but you hands would get wet but if you touch a steam with your hand it will burn you.
[For simplicity I used gas as steam and vapor as water vapor but you can replace it with gas and vapor]
very good, could let the ice form ... (muito bom esse experimento de física, poderia deixar formar o gelo talvez)
Which vaccuum pump did you use? Can you help me with the specifications of the pump?
Will you be able to tell us the boiling of water in increments of 2,000 feet, 4,000 feet and so on in Hg? Thanks!
Which vacuum pump which can accept condensates did you use? And what level of pressure did you use? I tried what you did with a 2 Pascal vacuum pump and it’s not enough powerful (nothing happened).
Removed the pressure and the air heat? What's left is empty cold space.
Cool vid - what would happen to water in deep space
So how much vacuum power is required to boil water or in my case wine? I know temp an altitude cause variation but sea level and 23 degrees Celsius.
Does the same concept (temperature of water dropping as it boils due to lowering pressure) apply to mixtures ? I am asking this because I recently learned about Pxy diagrams for vapor-liquid equilibrium, and as you know, the temperature in these diagrams remains constant even when we lower the pressure of a liquid mixture to form two phases.
In a mixture of two miscible liquids, the change in the vapor pressure (if temperature is fixed) or the change in temperature (if pressure is fixed) will determine how much of the mixture is in the liquid, two phase, or vapor phase state. Neither pressure nor temperature is held constant in my demo however the drop in pressure will facilitate the change of the liquid mixture to become a two - phase component but there will be limits on the ability of the two-phase component to become a mixture of complete vapor due the drop in temperature.
How much distilled water per hour can your equipment produce?
Can you put a gel shoe insole in your vacuum and see if it boils?
what happens to hot water in the chamber? would it then freeze quickly? woud it turn into fog?
so is it possible to vaccum a sewage water bcos doing so will kill the microorganism activity and boiling will create toxic material vapour or gas
If you took the hot air coming out of your mouth you could boil water. How many times do you repeat yourself?
after boiling in vacuum, the quantity of water looks same ??? Is there vaporization happens inside vacuum chamber and and that vapors produced from water sucked up by the vacuum pump ?
i would love to see this done with oil, marine diesel, and bunker c .
at what vacuum measurement does the water begin to boil??
Really cool thanks!!
If you boil water in a vacuum chamber, as the water boils does the water vapor that leaves it have a warmer temperature? Does it go to the top of the chamber?
I was wondering if you could give any insight as to how much vacuum standard lab glass could endure during a vacuum distillation? Would it be possible to boil water at 50C without cracking your glass? Thanks.
I just came to this video because I am building a water distillation system to filter out dirty water in the water storage tank. Some people watch physics videos for fun, others take advantage of physics in real life.
The demonstration in your video is perfect. I have a question regarding the vacuum pump. Which type of vacuum pump have you used in your demonstration ? also how to deal with the matter of water vapour condensing at the outlet of the vacuum pump? It may be very helpful for me..
Any pump will do
@@garywade7177 No. Most pumps use oil. Water does condense in the vacuum oil breaking the pump. A second question is which pressure is used as I also tried this using a 2 Pascals pressure and nothing happened.
Greetings to you. Am a Kenyan with curiosity, requesting if you don't mind, use these apparatus to test if wax can melt under reduced pressure or in a vacuum, at room temperature
can you put an ice cube into a vacuum chamber to see sublimation of water?😀
That would be nice. I remember it's how they make the instant coffee.
That sounds like it would work. I would like to see that!
Yes that is how a freeze dryer works
Can you explain how the water boiled despite being below its boiling point using vapor pressure, intermolecular forces, atmospheric pressure? If so that would be great!!!
@@yimszy4588Actaully two things determine a liquids boiling point, pressure & temperature. Most ppl think its only temperature, but when you look at a liquids boiling point ot is almost always rated at sea level.for intance Water boils at 212F at the beach in Miami but if you were to take that same water to say Mt Everest where the atmosphere pressure is lower and boil it you would notice something drastically changed and now your water will boil at 158F. Vapours in a liquid continually apply pressure upwards as if trying to escape. Normally atmospheric pressure blocks the escape but in a vacuum there is no pressure to hinder their movement so they leave the liquid which is called boiling. Since there is no heat involved in the process the boiling is cold. If you were able to see into a bottle of propane, the same thing would also happen, the pressure inside of the tank keeps the propane a liquid, but when you open the valve up the propane gas escapes and this lowers the pressure inside the tank and allows the liquid propane to begin boiling again creating more propane gas
I noticed a few DIY demonstrations such as yours where mason jars or beakers are used. What are the requirements of a vacuum container? Can it be a soft, flexible material? For instance, could I use a super strong garbage bag rather than a mason jar or beaker?
Lol, you want to boil cold water in a bag? Sounds hilarious, but you run into a problem - your pump will suck the bag in. However I'd like to see how liquid boils in a bag! Should be interesting. Maybe you can seal liquid in a bag and put it into vacuum container... But bag will rip because of increased volume, oh boy.
So is the gas coming off it higher than ambient temp?
23 degrees Celsius is about 73 to 75 degrees Fahrenheit which is warm.
That's amazing
Great video. What type of vacuum pump do you used? Do you know the flow rate? At work, we have a vacuum pump but I never see those kind of results.
Its a basic 2 stage demonstration pump that we got from one of our suppliers. If you are not getting results check your seal in your chamber.
What are the chances that all water molecules are doing the same thing? Molecules at the same temperature have a range of molecular motion. We call this a Boltzmann distribution which would show that there are many more molecules that have similar molecular motion while there will be less as move toward the higher end and the lower end of the graph ( like a bell curve).
Having different motions related to the molecules having different kinetic energy.
Can you explain how the water boiled despite being below its boiling point using vapor pressure, intermolecular forces, atmospheric pressure? If so that would be great!!!
Does water expand in a vacuum prior to boiling?
2 questions.
1-is there a formula for how much vacuum is needed to lower the boiling point a certain amount of degrees?
2 (maybe a dumber question)-in your vacuum chamber you show do the water molecules condensate at the top and fall back down?
What if you place the water in a vaccum over a flame ? When will it explode
How much vacuum was used in this experiment?
Please advice, I need to get water vapour out from water inside a vacuum chamber. What would happen if i seal the beaker with water inside a vacuum chamber ?
killim nishanth If you seal the beaker inside a vacuum chamber then you would lower water vapor as will all gases in the chamber. The seal around the water vapor will however prevent the lowered pressure from effecting the water in the beaker and there will be no boiling.
Is the vacuum machine sucking water in the system?
What's the maximum vacuum you can achieve while the water is boiling?
How much pressure are you pulling?
could this be a way to desalinate sea water? would the lower energy cost of heating the vacuumed water make up for the energy to power the vacuum as well as keeping the total energy cost lower then just boiling it at regular atmospheric pressure.
mustafa mcclatchey That sounds like a good idea. I'm not sure how well it would work, but it sounds like a good experiment to try, assuming that no salt water would damage the vacuum pump.
mustafa mcclatchey yes U.S. Navy does it daily unless it has an R.O. onboard ( mostly on subs)
Creating a vacum takes energy to, i dont know if it would be effecient or not tho
Good experiment and demo. How to extract the steam out of the Chamber?
I also have same doubt sir.
if you find any answers please post here.
Thank you!!
so Oxygen in H2O was removed?
The water is basically falling apart?
If inside od the vacuum chamber is vacuum, how come the glass chamber doesn't crush under the immense atmospheric pressure that is equal to G of three cars?
It makes a partial vacuum.
So if you had a solution of salt and water, and you wanted to retrieve the salt without loss or burning the salt. Could you place the solution in a vacuum while heating the solution on a hotplate to maintaining a ambient tempature?
Can't see any reason why not.
so if its not actually boiling, in like a heat sense, like what would purify it. does it create hydrogen gas? like combustible gas?
Not sure what you mean by "what would purify it". The water does boil here as well as the degassing of the dissolved gases like oxygen. The process is entirely physical and thus there are no chemical bonds broken or formed to create hydrogen gas.
So since the oxygen left, what is it now?
Is steam being produced at this lower temperature?
Steam is produced at all temperatures.
can you use this method to kill germs or diseases from lake water to make it drinkable , like boiling the traditional way
no, the temperature is what destroys the germs, not the conversion from liquid to gas its self.
OOPS! At 1:20 you mis spoke. Boiling occurs when the VAPOR PRESSURE (upward) is greater than the atmospheric pressure above it. How about adding a note to the video...?
What would everclear do
Why don't they make vacuum pump based air conditioners?
We do not see the water boiling due to the pressure drop, but simply some air bubbles that were dissolved in the water due to atmospheric pressure and expanding due to the pressure drop.
This explains the process stopping around 4 minutes, not because the temperature dropped but because most of the dissolved air was released.
The temperature drop is indeed due to vaporization but mostly not because of boiling conditions, simply because bubbles forced vaporization by expanding in the water.
If you had waited some more, you could have concluded that vaporization was due to water boiling.
Note that, when you heat water, air bubbles form because the virtual pressure of the dissolved air increases faster than the atmospheric pressure, because of the heating, when the virtual pressure goes above a certain threshold bubbles form.
Hence, in both cases the bubbles form because the virtual pressure crosses the threshold, but in the case of the vacuum chamber, it is because the threshold drops due to the external pressure drop, while in the case of the heat source, the virtual pressure increases due to heating.
I very much agree with all of your statements. When I first made this video many years ago I was trying to demonstrate the concept that boiling temperature is affected atmospheric pressure as any phase diagram of water supports. Degassing of the water is clearly occurring in the demo (due to Henry's Law) and the expanded gas molecules moving to the surface is clearly adding to the vaporization and subsequent loss of thermal energy.
I will however argue that boiling and degassing are inherently intertwined concepts. It is not as simple as saying that this phenomenon demonstrated is degassing and not boiling. Boiling of water and degassing do or can occur simultaneously and this can lead to increased boiling temperatures due to superheating (when we are not in a vacuum). Boiling temperatures will also depend on the surface of the container which affect cavitation of the dissolved gasses and the water vapor. That is why boiling chips are used.
So did the water boil in my demo by lowering the pressure? Was there only degassing? Did the degassing and boiling occur at similar pressures?
Does the degassing create the cavitation for the vapor molecules to collect into larger ones if in fact the water was boiling as very small water bubbles before it was degassed? This is a system that is much more complex than saying it is boiling or if its degassing.
do you put anything on the container to keep water vapors be sucked in and damage the pump?
how does a water aspirator work to lower the pressure? is that a cheaper option?
A water aspirator works by the Bernoulli Principle. Water runs through a pathway that also has a another pathway that is perpendicular to the flow of water. As water runs down it "organizes the air in a downward motion" in the perpendicular pathway which results in the air in that pathway to spend less time pushing outward and thus lowers the pressure. I do not believe that an aspirator can achieve a pressure lower enough to boil water at room temperature.
Can you drink it someone please answer
Trick question. The glass is completely full. If half of the glass's volume contains water and the additives in it, in most cases, the glass is full. The one situation in which the glass is not full is when you place a glass of pure water with no minerals, bacteria, or anything else that isn’t hydrogen or oxygen inside a vacuum chamber, the temperature of the water drops and it will boil. Then and only then is the glass half full and half empty.
Thank you we did this in ISL (a mix of Chemistry & Physics) and we had to write a reasoning what I got from this vid is Boiling happens when atm⬆️ is = to atm ⬇️
Can you explain how the water boiled despite being below its boiling point using vapor pressure, intermolecular forces, atmospheric pressure? If so that would be great!!!
the water molecules that are evaporating, are the hydogen bonds being broken? I didn't know the full definition of boiling before and understood it to be breaking the intermolecular forces.
Boiling is the temperature at which the vapor pressure equals the atmospheric pressure. The H-bonds yes are being broken to create the vapor pressure but these intermolecular forces are also broken when the boiling point has not been reached. All liquids evaporate below their boiling points due to the distribution of molecular motion or Kinetic Energy for all liquid molecules at a certain temperature. I often call the Boiling point the temperature where maximum evaporation occurs.
thank you
So then a refrigerator (cold food storage) that was a vacuum would use less energy? Would need just a simple vacuum pump rather than heat exchange?
Instead of cooling the atmosphere in the fridge, just remove the atmosphere and it is cold.
Changes in pressure is how refrigeration works. You can't transfer heat in a vacuum, since there is no matter for the heat to travel through. Also, pressurized containers would explode, soda and beer would go flat, and you wouldn't be able to open the door until the pressure was equalized.
Do you know what is the energy consumption of your vacuum pump (Kwh) to transform 1 liter of liquid water (+ 25Celsius) to 1 liter of ice (-10Celsius). Does it make sense to produce ice this way instead of standard technology?
won't it turn back to water once you relieve the pressure hence you need to keep it cold or transport it under pressure.
@@markbuckeye no there’s another video on TH-cam that shows the frozen water remains ice.
@@miles67733 I realize it is "ice" and will melt over time, not instantly but you either need to keep it under pressure or chilled to keep it from melting.
Can you explain how the water boiled despite being below its boiling point using vapor pressure, intermolecular forces, atmospheric pressure? If so that would be great!!!
@@yimszy4588 boiling point is a function of pressure...it is not a constant...this is why water boils at different temps/ altitude
Hi,
I am curious to know about bacterial destruction in water, boiled with this process (as bacteria is destroyed when we apply heat). if you know anything about it please tell me about it.
+Chandu k It's not the boiling that kills the bacteria, it's the temperature.
Hello. I have a Venturi type vacuum system. I can pull my chamber down to 25 HG, but can only make the water bubble on the side of the cup. I can not get the water to boil. Any idea what would cause that? I have tried different amounts of water, containers and two different gauges.
At room temperature, which is about 22 degrees Celsius the vapor pressure of water is about 20 mm Hg. If your pump is creating a chamber at 25 mm Hg then it's not low enough. You need match the pressure of the chamber to the vapor pressure to boil. You might be able to get a bit lower pressure by greasing the seal between the chamber top and the bottom.
+Ben Grodski thank you Ben. Now I know where I need to go from here to fix the issues.
You could use hot water since that would have higher vapor pressure and would require less vacuum.
Please can you tell me does boiling water in a vacuum create steam ?
Steam is water in the gas phase. So yes it does.
Do you have to worry about water getting into the vacuum pump? If it does affect the vacuum pump, how do you prevent the water getting into the pump? Would a collection container between the vacuum pump and the vacuum chamber work to collect the boiled water?
@@AMthefox interesting. Do you have any recommendations on vacuum inline traps?
Most pumps require vacuum oil. If you don’t pump permanent gas, water or ethanol will blend with the vacuum oil and the pump will break.
can anyone tell me the specifications of the pump used
yes . the answer is yes.
also why pressurized cans get colder as you spray them
Thats due to the expansion of gases. As they "throttle" through the small opening of the can the gas overcomes its attractive forces for each other by absorbing energy from its surroundings.
how long does it take to evaporate all the water?
I would presume at least 10 minutes.
my professor did this experjment, but he didn't create a vacuum,he let the air go out and fill it with water vapour . then he sealed it and
he cooled it and water started to boil .. How ?
I am interested in more details on how this was done but essentially if I am understanding you correctly your professor did create a partial vacuum by removing atmospheric air pressure (lowering the number of moles of air molecules) and cooling the the remaining water vapor (lowering the kinetic energy or motion of the water vapor). Those 2 actions would lower the pressure above the liquid enough to have the liquids vapor pressure equal the pressure above.
Would the water boil off completely at a certain pressure or would you have to keep the vacuum running because the liquid is turning into a gas state, replacing the air molecules that are pulled out of the chamber? I may have just answered my own question but feedback would be great!
My vacuum is not particularly strong so the it would boil off as you suggested. If I had a better vacuum the water would freeze.
@@MrGrodskiChemistry Wow, cool demonstration nonetheless. Thanks for the feedback!
@@MrGrodskiChemistry vacuum not strong? I tried what you did with a 2 Pascal vacuum pump and even after several hours, nothing happened.
If we put a thin slice of apple in the vacuum chamber, could it be dehydrated until becomes similar to the dehydrated apple slices which are sold in health food stores?
Best regards!
The results will not be as good if you first froze the apple and then lowered the pressure (freeze - drying). The phase diagram of water illustrates this. How much we could dry the apple is a good question.
MrGrodskiChemistry
So it would be hard to replicate... :-/
why did you stop it, you should've waited to reach zero Celsius that maybe water changes into ice
4:55 Why would he expect to see any freezing? 15C is far above 0C.
I know he mentioned freezing the water earlier in the video with a different pressure but that would also involve evaporating far more water and having the thermometer read much closer to 0C.
The phase changes like freezing/melting are dependent upon temperature AND pressure. You should take a look at a phase diagram of water
As the water is "boiling" would this help salt dissolve in the water faster then same temp water in normal atmospheric pressure? Thank you for your time sir
Gary the water is boiling at room temperature and solubility of a salt is dependent upon temperature so since the temperature of the water is the same (actually lower because evaporation is an endothermic process), the ability to dissolve salt would be the same. Interesting enough adding salt would lower the vapor pressure of water and raise the boiling point at atmospheric pressure.
Boiling is when the atmospheric pressure equals the vapor pressure and if we lower the pressure as in the demo above the vapor pressure needed to match the atmospheric pressure would be less. Vapor pressure (the force due to water molecules evaporating upward) of the water is dependent upon heat absorbed thus a lower amount of heat is needed to produce a vapor pressure to match atmospheric pressure. So the boiling can occur at room temperature if the pressure is low enough.
MrGrodskiChemistry And then post boiling, the energy used would allow the water to freeze (aside from extra factors).
Gary Calismax 😀😀😀😀😁😇😤
The water isnt actually "Boiling" in the sense they are trying to portray. Its simply due to the vacuum pulling out the gases. This is why I have grown to distrust the majority of scientists, as they mislead people into believing outlandish theories.
Nicholas, the temperature of 100C isn't special, it's just the number we've given to the temperature at which water boils at normal atmospheric pressure. Water can indeed boil at lower temperatures, as shown by the phase diagram: www.webassign.net/osgenchem1/10-figure-31.png
Things get a bit weird at triple points and beyond critical points, but water boiling at 80C at the tops of mountains or at 20C in this video are legitimate examples of the process of boiling.
can oil be boiled the same way to fry chips
+Mambo Bhoopathy It wouldn't fry anything.
Sir, in this experiment
Water definitely bubbled but became cool. So are you saying, this bubbling is called boiling?
Thank you
Well not necessarily. Water can boil with very small bubbles that are not visible. This is what can happen in a microwave. The bubbling can represent boiling and it also can represent de-gassing.
Have you tried DC electrolysis when the water is in the vacuum it may work as a catalyst and speed up DC electrolysis??
Can you please help me with some chemistry related issues that I'm having?
1. When hydrogen is heated up and reaches ignition temperature they say that it binds to oxygen in the air and forms H2O. After that, through the electrolysis of water, they say that oxygen and hydrogen are once again obtained and this validates the formula of water (H2O).
I, on the other hand believe something different. This is due to the fact that if the hydrogen and oxygen get combined it means that they remain electrically charged (which shouldn't be the case). If that were the case, then heating the water will make hydrogen ignite once more like before. When electrolysis is performed, no one knows how much oxygen there is in the container where water is found. What if the oxygen attracted at one end is the oxygen in the container and the water releases only hydrogen? It seems to me that after hydrogen burns what happens is actually that it loses its electron and becomes inactive. So, I would call water "inactive hydrogen" (not charged). Putting an electrical current through water reactivates the hydrogen. What do you think about this one? If you do believe the old formula, how can you tell how much oxygen was in the container at the start of the electrolysis and how much at the end?
2. I find it odd that intra-molecular relations are well explained, but inter-molecular ones are not.
If you ask me, the structure of an iron ingot, for example, could be explained more logical only with inter-atom (somewhat like intra-molecular) relations. But this would imply that an iron atom (Fe) or carbon atom (C) has the supposed shape of a cube, where each face of the cube is a potential connection to another atom, from a 3D perspective. A mound of powder iron shouldn't be equal to an iron ingot of same volume, because there are no atom connections in the powder (even though it's the same element). So, for the iron ingot, the difference could be either that each iron atom is held to its neighbors by electrical connections, either has other atoms between them which perform the binding.
I don't have such advanced knowledge about chemistry, but I tried searching and understanding about the topics that interested me and these are the conclusions that I reached. Am I missing something? Is it something which gives more sense to the official existing explanations?
Your questions would be better served in studying the basics of chemical bonding specifically covalent and metallic bonding. When water is made by the combustion of hydrogen the water is not electrically charged due to the protons and the electrons in the molecule being balanced. The force that keeps the atoms together is the electrostatic attraction of the protons of the nucleus and the valance electrons so the molecules of water are neutral even though there are electrostatic attractions keeping the atoms together. There is also a stability component in all of this as well. Water molecule are more stable than hydrogen and oxygen molecules and the contribution of energy to the surroundings that is released to get to a lower energy level (higher stability) helps drives this process. In short it takes a lot of energy to break the covalent bonds of water back into hydrogen and oxygen because of its stability and heating water would not be enough energy to do so. Electrolysis would provide this energy and when we collect the gases from this process we always get a 2 : 1 ratio of hydrogen and oxygen and through Avogadro's hypothesis this proves the formula of water.
Ok, thanks for the response. If you don't mind, a few more questions:
1. How is the ratio between oxygen and hydrogen measured (at the start of the experiment and at the end)?
*The force that keeps the atoms together is the electrostatic attraction of the protons of the nucleus and the valance electrons so the molecules of water are neutral even though there are electrostatic attractions keeping the atoms together.*
2. For table salt which is found in large crystals, how are these NaCl molecules kept together, since the molecules have a neutral charge (as you said)?
1. There is no volume of oxygen or hydrogen gas being collected at the beginning of the electrolysis of water ONLY water vapor. Electrolysis is redox reaction that is a non-spontaneous process that forces the water to undergo a oxidation and reduction that it normally would not do (because of its stability). Water that gets oxidized becomes oxygen gas and water that gets reduced becomes hydrogen gas and this gets collected at each electrode. The volume of hydrogen is always twice that of oxygen.
2. NaCl are not molecules. They are charged states of atoms that get formed because they are more stable as an ion than neutral based on their electron arrangement. They make crystals because they attract other ions in all directions. The formula of table salt, NaCl, is written this way because there is one Na+ for every Cl-. This is called ionic bonding which is different than covalent bonding in water. You should really learn your basic chemical bonding principles.
Ok.
Is this principle use to make freezer work
Sausage N Bellenz Yes, this is exactly how they work, and heat pumps too. Temperature and pressure are proportional according to the Noble Gas Law.
PV=nRT
Water does not change temperature as it boils (Q=mL); the lowered temperature is actually due to heat being removed from the surrounding environment, including the thermometer itself [(delta)T=Q/mc].
Clearly in this demonstration water is changing its temperature as it boils. Now I agree that under constant pressure and at or near standard pressure the temperature of the water will not change as the heat absorbed by the water needed to produce a vapor pressure equal to that of atmospheric pressure is enough to replace the kinetic energy converted to potential energy in the phase change. In this case however the pressure is not constant and is being lowered throughout the demonstration. The water cannot replace the heat lost fast enough at room temperature, as the higher kinetic energy molecules evaporate due to water's high specific heat. Thus the average kinetic energy or temperature drops. The water keeps boiling because the pressure keeps dropping and the lowered pressure requires less vapor pressure to boil. If this were not the case the water would cease boiling. Also, your assertion that heat is being removed is the reason has limitations because we are using room temperature water so there would be very little if any heat transferred. Removing the water molecules with the higher kinetic energy lowers the temperature of the water and the lowered pressure makes it reboil at that lowered temperature.
MrGrodskiChemistry Thank you for your thorough response. I was simply confused by what I was seeing, and you helped clarify it for me. I was using equations like Q=mL and Q=mc(delta)T in cases in which they are not applicable. That being said, I am curious as to whether or not the temperature of the beaker decreased, even slightly. The analogy may not be completely valid, but the nozzle of a propane tank decreases because the propane absorbs heat from the outside environment when it boils. Then again, propane's boiling point is much less than room temperature.
I would not be surprised either way as to whether or not the beaker's temperature decreased.
BlackSkullRacer613 The decrease in temperature you are talking about when gases expand through a small opening is called the Joule - Thompson effect.
As the propane expands out of the container (high pressure) it does work on the surroundings (which is under lower pressure). The work must come from the internal energy of the gas so that the internal energy decreases. Since the internal energy of an ideal gas in only dependent on its kinetic energy that means that the temperature of the gas must decrease. There is no transfer of heat in this process. Its more like kinetic energy being converted to potential energy.
-The beaker did get colder as the temperature of the water dropped. Glass has a lower specific heat than water and the beaker would transfer its heat.
Would it boil down to ice by starting with hot water as it should boil down quicker with your limited vacuum?
Using hot water would not achieve ice quicker. It would achieve boiling faster as warmer water has a higher vapor pressure, thus it would take less of a vacuum to make the warm water boil. If you look at the phase diagram of water the conditions of pressure and temperature have to be lower for ice to form. A lot heat would have to be dissipated before the triple point is achieved and this would take temp of 0.01 Celsius and pressure of about 0.006 atm.
Thanks for the info.
MrGrodskiChemistry In retrospect water will boil faster starting with hot water and may ice faster as water loses heat in a variable fashion.
Vibration due to mass.
Negative mass.(vaccum)energy.
Water mass.
Mercury also vibration.
Lowering the pressure means the electrons slow down, they don't have as many other particles to excite them. Absolute vacuum is absolute zero, where nothing moves, because there is nothing there to move (all matter has been removed)
David Emmett Atoms slow down when temperature decreases. The speed of the electrons around the nucleus remains unchanged, as this is determined by the laws of quantum mechanics. Schroediger's equation for a stationary state is temperature-independent.
David Emmett 👍
David Emmett 👏
Question; So, would a spacesuit, stop this from happening to a human body in space?
Mike Arthut spaceships and space suits are pressurised
@@zachb1706 Ok, what IS the PSI? I want to do an experiment, make a mock up space suit, and put it in a vacuum.I am an Flat Earth Researcher. On a small scale. maybe just a box, or something to simulate the same conditions astronauts have, in space.
It’s usually pressurised to 1 bar (1 atmosphere). Pretty much what you have down here on earth.
why doesn't it get hot scene Bernoulli's principle would seem to apply here correct because when the pressure comes back it should generate heat
The most energetic water molecules are the water molecules that will vaporize and thus since you are losing energy the temperature drops. Evaporation is an endothermic process and there is also cooling due to gas expanding into the vacuum. The gas (water vapor) increases in potential energy as it moves away from each other near the beaker and into the vacuum and since energy is conserved the kinetic energy must decrease and so does temperature.
Hello sir
I am SureshBabu from india and i am a chemical engineering candidate and i see your videos, it is very knowledgable. I have few doubts based on this experiment
I handling vacuum distillation column in my company to seperate the two higher boiling point component at the vacuum of about 15 to 20 mmHgA. In your videos water is at room temp, assume that the two higher boiling liquid(A+B) kept in beaker at the temp of about 180 C at atmospheric pressure. Component A boil at 180 C @17mmHgA and Component B boil at 240 C @17mmHgA. Now i start to pull the vacuum in the closed container, when the pressure reaches 15 to 20mmHgA component A starts to boil and evaporate, then the vapour is sucked by vacuum pump. During this condition what would be the temperature of the component B wherther it reduces (or) still at same temperature of about 180 C.
Assuming that the 2 liquids are miscible then the temperature of B must drop, however you are maintaining a temperature of 180 C in this distillation with a heat source that is thermodynamically favored to regulate a constant temperature. The heat source is transferring thermal energy to the liquids that are losing it through boiling and or evaporation.. Liquid A is evaporating/boiling and is losing kinetic energy and Liquid B although not boiling is also evaporating, thus it is losing molecules with the largest kinetic energy. The lower thermal energy in the liquids provide a pathway for heat from the heat source to "reheat" the liquids.
Thank you for reply me
The two liquid are miscible, you are told that when the component B drops its temp during boiling of component A that time we should give energy in terms of heat to maintain the temp of about 180 C am i correct sir.
When i did not supply energy during temp drop of component B, what would be the temp of component B whether it decreses further (or) not.
Not sure If I understand your question. Are asking me what would be the temperature of component B if no external heat was applied?
That is a very complex problem that would require measurement of many variables.
sir I am not asking the exact temp of component B whether it further decreases or not during boiling of component A under vacuum.
SURESH BABU This is sooo embarrassing!!! I am 11 and i can't understand what you are saying. But i am very concerned that it is a very good point.
if the water "boiled" it would become steam,which would expand 35 times and no longer be under vacuum
The number of water molecules in the container doesn't change, they are now able to occupy more space as they are not impeded by air.
Is it boiling, or it's just losing the gas molecules in the water?
This is a point of debate in this comment section. I do agree that there is degassing occurring but also boiling.
I am interested in the boiling rate ... how many cc/minute will boil off if you keep the pressure below 0.2 atm ???
I can't answer your question, but I can say that you will need to keep temperature at the same point, otherwise the rate will slow down equally to amount of energy excluded from system.
Also you need to have a constant supply of water, because otherwise all of it will eventually boil, and know somewhat constant volume of liquid in reservoir, because this also affects the rate, so your rate should rather be measured in "cc per liter per minute at a given temperature and pressure"
After that I think you can just find a table of corresponding values (at least for distilled water they should exist) to calculate exact values for your input data, like 0.2 atm & 25 degrees Celsius (table will more likely stick to Kelvin but hey)
Doing that to liquid nitrogen makes it freeze into nitrogen ice.
Hey guys my Chem teacher told me to do homework so someone pls tell me why did the temperature DROP after it started boiling?
The water molecules absorbs energy to break intermolecular bonds to enter the gaseous state during boiling. So the kinetic energy of the rest of the liquid state water molecules is lowered resulting the temperature to drop.(Oh but it's a year late to do your homework. )
What if you use soda instead of water ??
That would be interesting. I would believe you would see 2 waves of bubbles. The first would be the immediate loss of carbon dioxide from the soda as the lower pressure lowers solubility of the gas in the solution. The second wave of bubbles would be water as the pressure continues to be lowered to boil the water in the mixture.
Will it cook macaroni and cheese
no
Why doesn’t the thermometer explode in vacuum?
It is a partial vacuum.
Very impressive.
How could one harvest the vapor in that vacuum chamber and condense it into purified water?
You could condense the vapor from the return on the vacuum pump but it might be easier just to distill water if you are looking for purification.
Thanks. Distilling is much easier, but due to climate and available resources, I am investigating other costly alternatives. I put a quart of water in my vacuum chamber after the initial boil _(:30sec~ @ 900mT)_ it stopped bubbling and became still and then froze solid around 500-400mT, I did get some light Ice on the walls of the chamber. I suspect I need a heat source inside to prevent freezing; then perhaps collect the ice off the walls? PS: My vacuum chamber also has a refrigerant coil on the outside wall that can bring the internal temp to -50F.
Question #2: Water companies tell us to boil the water if a pipe has broken, or if one needs to drink pond water, etc; to kill waterborne pathogens and other nasty organisms. I was wondering if boiling it at room temperature in a vacuum would kill said organisms; or is this potable water goal a function of temperature vs the boil?
Bruce Wayne The water companies are usually assuming that that you are boiling water at standard pressure, which would mean that your water is at 100 degrees Celsius. Water boiling at room temperature as in my demonstration would not kill harmful microbes as the temperature is not high enough.
Some cities the water boils at 98, 95, 89°C
Can I use this way to chill my soda in matter of minutes Tho??
T-Rex DaBeast If you succeeded, your soda would be incredibly flat. If you left it in the can or bottle, you might end up with an accidental bomb!
Buddy Clem the best type of bomb
Coca cola espuma