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- เผยแพร่เมื่อ 29 พ.ย. 2024
- Does hot water freeze faster than cold water? Turns out, the answer to this question is a lot trickier than it seems!
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Does that mean cold water will boil faster than hot water **angry Gordon Ramsey noises**..
prob
Nope
of course it does simple physics.
( ;
If it is microwaved he may have a heart attack.
I came from the same video LOL!
Knowledge is power, France is bacon.
Imgurian or Redditor? (Most likely things, maybe 4Chan?)
Eric The Epic A little of both actually - no 4chan though. =P
+Erik Great Grandpappy said French guns are the best to buy. They've never been used and they've only been dropped once.
+Salty Diarrhea twice
LHommeDeCave non, uno
My grandfather told me this back in the 1970's. He said his first car didn't have any anti-freeze, so he used to drain the water when it was cold, and refill it when he needed to go somewhere. He also said that if you put the hot water back in the engine, it would freeze faster than putting cold water in. This made no sense to me, and I was probably 9 or 10 years old when he shared this with me. Being a scientific type, I did not believe him. My grandmother and I spent a day just heating and freezing samples of tap water to test his claim. Our results were inconclusive. Completely random results. Sometimes the boiling water would freeze a minute before the 40 degree F water. Sometimes the cold water would freeze first. I learned a lot about variables and rigor from my grandmother that day, but I also learned that my grandfather wasn't necessarily full of crap.
great story
Normally the science news goes something like "here's something new we discovered and you need to know about it because it's cool". This one is more "we don't know, that's interesting too, give this a whack if you're feeling curious". I love it!
I hate it. Why is this so hard for science to figure out lol.
"Aristotle said the same thing in the year 4 BCE"
*raises eyebrow, checks Wikipedia*
Aristotle: Born 384 BC, Died 322 BC.
Perhaps a different Aristotle that the one we all know and love?
The century my man
I'll probably be trying this in my lab next weekend with our ultra-pure water and some sealed containers. I'll keep you posted!
By checking on them every five minutes or so.
I could also pour out the liquid water to quantify exactly how much water has frozen, and by doing it repeatedly on a few dozen containers or so, plot this against time, but that's going into too much effort for something that's not meant to be more than a fun thing to do out of personal curiosity while I spend part of my week-end in the lab.
sam
I'd love to. But I don't even have a camera, so...
+piranha031091 leaving this comment here just to see how it goes
iamihop Hmmm, why didn't I think of that! I do have several K-type thermocouples.
Though since I don't know how to hook them up to a computer to automatically take measurments and save them, I'd have to manually check up on them. And since I will be in the lab to do other stuff, I won't have the time to do so very regularly anyway.
Plus, thermocouples don't tell you about temperature inhomogeneities, which may be primordial here. The critical point really is "how much of the water has frozen in how long".
A full study would of course imply doing it in containers of varying size, varying wall thermal conductivity, and at varying starting temperature and freezer temperature. But that's no week-end project!
Also, I haven't even checked the literature on the topic yet. (but it's getting really late here, so... tommorow.)
+piranha031091 l'll be checking this comment.
Rate of evaporation is very important to consider because it's transferring thermal energy. Cold air is also dryer then warm air, so there's going to be very rapid evaporation and temperature change with hotter water. I suspect water freezes on top first because there's a greater thermal transfer with evaporation taking place. It's how we cool our bodies with sweat and why we can't cool ourselves well in a humid environment. Cold dry air cools us immediately as you can see the water vapor coming off you body when it's cold enough outside.
Side note: When I use denatured alcohol to clean my 3D resin prints I wave my hands in the air to dry the alcohol off my gloves quickly and my gloves get very cold since alcohol evaporates rapidly. It's an interesting effect. 👍
Exactly. Impurities is what I was just thinking, raising, or lowering the freezing point, depending what the impurities are. Seems to make a lot of sense.
What is that grumming sound in your ears that occurs sometimes if you yawn and close your eyes real tight??
Im fairly sure your hearing your blood flowing through your ears
Your eardrums vibrating
That's just your jaw muscles contracting really tight
5 different answers at this point, one could be right, lol
+cosi321 pretty sure those are your jaw muscles
There is a critical point that I think helps regular people understand why this might look possible and why it’s so easy for people to produce conflicting results. It takes significantly less energy to cool water down than it does to actually turn liquid water into ice (aka freeze). So realistically the energy required to freeze hot water and the energy required to freeze cool water are much much closer than people would think intuitively. It makes sense that literally changing matter from one phase to another would take a ton of energy but very easy to overlook unless you start thinking about it lol
"maybe youll get an effect named after you" lmaoo
"Who knows, maybe you'll get an effect named after you."
Mpemba effect
we all have water people in Africa crying
Not the only one to mention this, but why can't they just use pure water?
+Ionlymadethistoleavecoments Completely pure water doesn't freeze because it needs a structure around which to form, which is provided by impurities.
+CuriosityKilledTheMartianCat if you constantly shake destilled water when it is on the freeser it will freese
+Hugo Fernandes yeah but what container will you use? glass, metal, plastic? all materials are solvable in water, some really low but enough to be counted as tiny bit of impurities...
+Ionlymadethistoleavecoments We have no pure water to test on.
+Aerroon At Earth level, water would evaporate in space, not freeze :)
hot water has less dissolved oxygen or air bubbles which aids with a harder surface.I worked at a rink when i was younger, They fill the zamboni up with very hot water before it goes on the rink.
I had always thought it had to do with the loss of energy of excited particles from thermal change, such that excited faster moving particles will expend more energy to stay in the same excited state as their energy is drawn and changed.
Those patreon guys need to up their game "who keep these answers coming' .. there was no (and in so many glorious ways that I'm rushing to empty the freezer and to the experiment myself) answer to this question. Keep up the good, excellent, work!!
But which freezes faster on Mars?
That is an another story for what if
@@beallay3541 I don't think the guy is still alive after 5 years
@@beallay3541 The water will just immediately evaporate cause of Mar's thin atmosphere
You maybe
@@Amlaeuxrai I will return in 4.5 years
That is, honestly, one of the coolest observations I've ever heard of.
they can build the LHC but not figure this out? Imagine the headlines: "Nobel prize for guy who figures out boiling water"
I did this with two freezer bags, the same mass of distilled water from the same source (the more the merrier, a kilogram would be ideal), and the bags being sealed with the water at the same temperature, with the air sucked out. So I eliminated most contaminants, loss of mass from evaporation, loss of energy through latent heat of evaporation, and any large difference in dissolved gasses. Cooled one bag to just a few degrees above freezing in ice water, put other bag in boiling water, dried both bags, tossed them in freezer on top of sheet of styrofoam (to eliminate conduction.) Easy to try ... everyone should do it. Several times.
What?! At 0:52 the video claims that Aristotle made the claim in 4 BCE. Aristotle was Alexander the Great's teacher in the 4th CENTURY BCE... lol
Bce refers to an era so the fourth era before Christ or whatever. I think this is due to the fact that the years had been irregularly recorded for some time which is why they can't for sure give the years and give the era instead.
+iamihop you're right I misread my source sorry about that
+iamihop I guess I just couldn't accept they had made that big a mistake
But what if a superior alien race comes to Earth and says: humans you have the chance to get into our galactical empire with unlimited knowledge and resources, you just need to prove your intelligence by answering a simple question: Does Hot Water Freeze Faster Than Cold Water?
And we would miss our chance:(
it was the moment human knew they fucked up
We would say hot water.
The hot water has to cool to the exact same temperature as the cold water at some point and then somehow surpass it. If both samples of water are the same and in a closed system this makes no sense. whats much more likely to effect it is where you put it in the freezer.
+Spencer Teolis Except that in closed systems, the speed at which it gets closer and closer to entropy is higher the total energy of it is and the more heterogeneous it is.
+ANDELE3025 That is completely true, but it somewhat misses the point.
If the containers are sealed, the liquid inside of equal compositions and at the same temperature and pressure, their entropy should be equivalent if each system is in thermodynamic equilibrium.
Presumably these systems will have to cross this point if the hot water is to freeze first. In terms of pure thermodynamics, it is not clear why these systems would behave differently and allow this to occur.
If there is a mechanism behind this, it will have to involve molecular kinetics and mass transfer and not just thermodynamics.
+Blake Blast thats just not true. Water that is at 99 degrees celsius will certainly come to a boil faster than water (or ice) at 0 degrees celsius. Also it is possible for an entire pot of water to boil all at once, however every atom would have to have enough energy (be hot enough) to become a gas and it would have to be under a lot of pressure which was then released for that to happen.
Ice crystals form differently depending on circumstances. I'm not by any means claiming this to be accurate, but imagine if faster moving molecules and exaggerated temperature differences allowed for a flimsy crystalline lattice to be smashed together freezing the water quicker but less structurally sound.
Also, I imagine heat would cause impurities to stay near the bottom allowing ice crystals to form easier.
+Spencer Teolis Not necessarily, like one of the theories suggests, convection currents may play a large role. The currents effectively creates more surface area for heat to transfer from and more evenly all throughout, and because rate of heat transfer is based on temperature difference, it is much easier/faster to cool something from 100C to 50C in a 0C environment than from 5C to 0C.The convection currents would circulate the warmer water to the sides of the containers where it would transfer heat/energy much faster than if cooler water was in it's place, like in the other container where the water essentially stagnates in place, thus reducing the total energy of the hot water system much faster than the cold water. Since the entire hot water system is cooled instead of just the sides, it allows more probability for freezing to occur from the randomly distributed impurities.
Was it the ghost of Aristotle? He died in the mid 300s bc 4 bc Is like confusing Newton and hawking,s time on earth.
+Anthony Dobbs To this day the ghost of Aristotle hangs around in physics classrooms, whispering ideas about the telos of the movement of energy in thermal experiments.
I too was immediately struck by this -- 4 BCE?? Really, that is quite a bit off.
@@karlkutac1800 you realise 300 BCE comes after 400 BCE?
@@sadguy521 I think they meant the 4th century BCE
A pipe froze in my house last winter. It was the Hot water pipe. (and it was in the same basic location as the cold water pipe).
It was a dead line in our house, but it still had pressure to it, it was capped off on the far end.
I was rather surprised, but my plumber said that the hot lines freeze first, based on their experience. Interesting.
this is because hot water as you probably know the molecules are moving faster than cold water.
because of this the hot water has more *surface* area to cool.
Cuz hot water condenses the outside humidity onto the pipe then freezing it creating a large heat sink
I used to work at an ice arena and when we used hot water during the resurface process is always seemed to freeze much faster then the cold and also gave a higher gloss to the surface. The gloss was more likely do to melting the surface ans smoothings things out a little better.
I've been waiting quite awhile for this to be answered. Thanks for getting to it!
If the results come in nearly 50% yes vs no, and time that either freezes before the other is essentially marginal, than isn't the answer no? If the hot water cools faster, and eventually meets with the temperature of the water that began cooler, wouldn't they start freezing at the same rate? The water doesn't remember that it was warmer at an earlier point.
The water might not know its original temperature, but that does not change the fact that it is cooling at a certain speed. Also if the water actually happened to change the speed at which it was freezing depending on the temperature then the hot water would never reach the cold waters temperature.
Example:
Assume you have three bowls of water. One hot, one medium and one cool. If we assume that the hot water is losing it's tempature the fastest it would at some point reach the cooler waters temperature. If it so happened that once this occured the hot water would slow down so that its freeze rate matched the cooler ones. The problem with this would be that we have assumed that the freeze rate for the hot water was allways greater then that of the cooler water.
Also the hot water has allready passed the medium waters temperature which means that the hot water has changed to the medium waters freezing rate. This would mean that the cold water would allways freeze faster.
If the hot water froze slower then the cold water (but with increasing rate for each new temperature achieved) the cold water would still allways freeze faster.
+fartzinwind Laws of thermodynamics, it wouldnt reduce its speed at which temperature/energy is equalized as long as something doesnt try to stop it from doing that (e.g. impurities in water, uneven cooling, etc).
+IcIcyEyes We don't have to assume anything about the rate of change in the hot vs cold water. If you expose two equal volumes of water into a freezing environment, the warmer of the two will lose heat faster. That's a known thing about water already.
+fartzinwind I'm talking controlled tests. Make sure that impurities are as close to the same as possible, make sure the containers are identical, leave no room escaping vapor. Hell you could even purposefully agitate both containers of water equally. That would cancel out the water trying to have internal currents, and somewhat keep the flow of water in the containers the same.
Sorry my bad, long time since I knew any of this. The point I was trying to make was that if the waters freeze rate was only dependant on the temperature then the cold water would would allways hit the lower temperature in less time.
Edit: Early morning spelling errors.
hot water cools faster due to the molecules moving faster and more spread out creating more surface area to cool.
I am talking about -0 degrees
if you throw a pan of boiling water in the air compared to 42 degree water you would understand that boiling water cools faster because of larger surface area and shock factor.
0:49 Wait... If Erasto Mpemba discovered the Mpemba Effect (his namesake) with milk...
Then why the actual heck haven't we been trying this out with milk instead of water????
I feel like the answer to this is relatively simple. If
experiments find that sometimes hot water freezes faster, and sometimes cold
water freezes faster, and the difference in time is negligible, then from a
statistical interpretation of the data, one can conclude that there is no
difference. For example, when I was in college I had a lab experiment that was
meant to prove the value of “R” in PV=nRT. We had complex glassware setup with
a gas inside. We took measurements of P, V, and T, and previously calculated n,
which then allowed us to determine the value of “R”. Here’s the thing though,
we took several measurements of P, V and T. If we had presented our data just
based on one set of measurements, that would have been considered bad science.
The point of taking multiple measurements is not only to reproduce data, but
also to achieve the closest measurement to its true value. In other words, despite
the fluctuating data and results, if we take the average data of each
experiment, the answer we get is “no difference”. What may be contributing to
the inconsistent data may be other factors, fluctuations, even possible
molecular or quantum effects …who knows. However, whatever the cause of these
fluctuations may be, it is probably safe to say that it is independent of the
experiment.
this is the first time I see scishow answers "we dont know" lol
Wow a place to actually use all the pchem I've been learning! Let's see...
This experiment should be performed with small amounts of water to eliminate the insulating effect of ice once it begins to form on the walls of a container. At that point it should become clear that water at 0C
Why not just use two samples of distilled water, to remove the particles variable.
Water is NEVER pure (at the very least it has dissolved gasses inside it). It is the type of imperfections present which determines the waters freezing point. Water with absolutely no nucleation sites will not freeze but this is not physically possible. See my comment about freezing points of liquids for an in-depth explanation.
Amazing how simplicity isn't so simple.
Could we not use two precise measurments of distilled water (one heated and one not )in two seperate freeezers with equal conditions on a timer? How would that not produce accurate enough results?
There are to many variables affecting the experiment for us to be enable to practically and in a repeatable manner perform it. Things like vibration from a train 20 km away will effect the internal flow of the liquid in a unpredictable way and so on.
I think that might be a little bit extreme, if we were to take that in consideration than surely any experiment conducted within 20 km of a functioning train involving freezing any fluids would have to be thrown out.
Even if thats the case , if we really want to get an accurate reading , whats stopping someone doing this in the middle of the australian outback where there are absolutly no vibrations whatsoever.
There seems to be a solution that we could have come to by now. Correct me of course if im wrong , I dont come from a scientific background and could just be talking out of my arse.
I'm also a layman so might be completely wrong. But as I see it the problem is that a single molecule of impurity can change the freezing point of a otherwise pure liquid dramatically. Maybe you seen all those videos of super cooled coca cola and other liquids. You can cool undisturbed 100% pure water down to about negative 40 degree Celsius before it freezes or rather it glassifies. A minute amount of impurities might have a noticeable effect but it can also depending of local conditions within the liquid be completely mute. The cola stays frozen even with impurities because you start of by manipulating the pressure and thous boiling point. When you open the bottle the cola stays frozen until the impurities are disturbed and acts like a seed for crystallization. You can compare the problem to a whether predictions it is just that when the liquid is super cooled it is also in a super unstable condition where extremely tiny changes can tip the system into a new more stable state.
But sure it might be ways to do it somehow but I think it answers at least the practical side of your question anyway, if it is possible it is very very hard and expensive.
But so its proven that it is specifically about freezing? The temperature does not reach 0 faster in hot water? Cause my guess would be that the bigger differences in temperature causes stronger currents to allow for more efficient cooling. Don't know if these currents would stick around after a few hours of slowly cooling though.
Water is NEVER pure (at the very least it has dissolved gasses inside it). It is the type of imperfections present which determines the waters freezing point. Water with absolutely no nucleation sites will not freeze but this is not physically possible. See my comment about freezing points of liquids for an in-depth explanation.
I think this channel is the only channel that I watch all the videos that are uploaded, well done guys 😂
Why does peanut butter always get stuck between my toes?
+Simon The Digger Because it's difficult to make sandwiches with no arms.
+Simon The Digger Because you like how your dog's tongue feels on your feet. :3
+Albie Beck i damn near spit my soda out when i saw that comment!!
It's called the PB Effect
i have the same problem, only that it's on between my buttcheeks
i always wake up like that and it's getting irritating
Hello, I am a material scientist and my thoughts may be a little skewed on this. But here they are… I am curious to know what the purity of the water is that’s being used for these experiments. Or if there are extractables from the containers that are being used for these experiments. This is going to sound like a hand waving explanation for which I have no experiments to prove. Say there are impurities in the water/container that dissolves readily when heated. Once dissolved, these impurities may take a long time to precipitate back out, if at all. However, these impurities may take an extremely long time to dissolve in the first place in chilled water, if at all. These impurities could be crystallized mineral deposits or extractables from the container being used. In this situation, the mineral deposits or undissolved solids can serve as nucleation sites that lower the energy for the crystallization of water.
"Who know? Maybe you'll get an affect named after you." lol
*effect
this was not the answer I was expecting. very nice video!
I did this for my science fair project in 6th grade which is an idea I thought of all by myself and completed all by my self. The hot water froze first.
My teacher told me it was dumb, that I was too, and failed me.
🤭
The paper "Effect of Initial Temperature on Water Aggregation at a Cold Surface" by Lemont B. Kier* and Chao-Kun Cheng tries to explain this through a cellular automaton simulation of water cells. They try to explain it from a structural perspective of water.
They suggest that at higher temperatures, there are more interactive water cells that are either not bonded (f0) or bonded to just one other water cell (f1).
They consider f4 to be solid water.
"This difference in the initial structure of water at the two temperatures produces a significantly greater opportunity for rapid and extensive migration of the less bonded f0 and f1 water cells in the warmer water. Under these circumstances, the formation of higher order clusters, as measured by the f4 parameter content, is more likely to occur sooner in the originally warm water."
I don't understand their model super well, so feel free to read the paper yourself!
Can disprove logically: hot water has to BECOME cold water in order for it to freeze. So, any effect will be down to whether heating water does something to it to later allow it to freeze faster, for example, causing dissolved gasses to escape may make the water a better conductor, allowing heat to transfer out faster. So, it's all down to the side conditions of the experiment, not the main thing being tested for.
Thanks
1:42 , There are not a lot of "theories" as to why this happens. There are hypotheses.
***** this is a Science Show. There is no use for this.
+Andrew Chason This is a science show for a casual audience, with some more technical viewers. The colloquial use is understandable.
+UnashamedlyHentai No! COLLOQUIAL IS EVIL! Proper science terms are precious...
+Andrew Chason isn't it the same?
It has been known for quite sometime that the hot water lines in our home freeze faster or sooner than the cold water lines. It could be that hot lines can create a nucleation site sooner supporting the ice crystals. It has also been theorised that due to the more energy and spacing of hot water, the bigger gaps between the molecules allows for faster loss of thermal energy. Well just thought I'd share, thank you!
Aristotle wasn't alive in 4 B.C. guys.
+Biedrik they corrected it in a youtube annotation.
In 400 Bc they say now
Are we talking minor temperature variations? Because I would imagine it would take longer to freeze 90C water as opposed to 10C water. Maybe not a lot longer because the temperature differential is bigger for the hotter water and therefore the cooling would go faster in the beginning but should be pretty similar when the hot water hits 10C.
Here's my theory, Hot water raises the temperature of the freezer making it cycle more frequently freezing the water faster.
only thing i can think of is that hot water is less dense than cold water, closer to the density of ice than cold water, either the pressure differential on the surface of the water is playing a role, or less likely the cold water expanding into ice has to contend with gravity in a contained rigid container (rise up the container as it takes up more room frozen than liquid). its probably a combination of ALL of it (impurities and SHAPE of the containers used imho are MOST likely the largest sources of discrepancies). that being said, water has a rather high specific heat due to it having such a high amount of polarity with so little size making it take more energy than most liquids to raise in temperature each degree (or in this case, more energy to pump the heat away from water because the effect works both ways if i remember correctly)
would VERY much like to see this experiment done in microgravity with both rigid and non-rigid containers.
We can send people in space, but we can't know something that seems simple such as this. That blows my mind.
seriously
I believe that the Mpemba Effect is plausible. Liquid water atoms are actually more tightly packed than solid water atoms. This is because the atoms create a certain hexagonal structure when the water is solid; this is why solid water is less dense than liquid water (and is why when you freeze water in a water bottle, there seems to be more than what you began with). Also, heating liquid water will cause the atoms to spread apart.
So if we begin to freeze hot water, the atoms are probably already around the distance that they need to be to form this hexagonal structure. But heating cold water, where the atoms are in a more tightly packed mesh than the hot water, it will take more time for the atoms to spread out and begin forming the structure. The inconsistent results from experiments are likely due to atoms being in somewhat different positions to the others for each trial.
Wait what? 1:25 Solute containing water freezes at a lower, not higher, temperature.
The answer is simple, and it has nothing to do with the water being cold or not. Water can supercool in some cases, and the conditions for supercooling are so delicate that two water containers in the same freezer can freeze differently. Surely hot water is unfavoured because no matter what you do, you'll have to remove that excess energy first (which takes time), while you haven't to with cold water. But cold water can supercool and start freezing after hot water has been cooled to 0°C (and started freezing). It also doesn't happen sometimes, and as I said the conditions are really delicate, so it makes sense that the experiment gives different results every time.
How did Aristotle freeze water?
Hello sci show answer me , he didn't have a freezer soooooo wtf ? 😇
LOL IDK!
Maybe is was.. Oh idk... Cold outside?!
I copy and pasted this answer from an engineer on a different website:
Until the invention of the refrigeration cycle, all ice was a result of natural freezing. Ancient people's had basically two options, if they wanted ice in hot weather. If they lived near mountains that had snow on top, they could have ice and snow carted down, or they could try to store ice during the winter in such a way that it wouldn't all melt before the weather warmed up. Ice houses, generally insulated with straw, have been around in one form or another for a long time.
In the early 19th century, an American entrepreneur worked out a way to cut ice out of frozen lakes, pack it in sawdust to insulate it, and ship it across the country (and eventually across the world. Unfortunately for him, it was a pretty easy process for competitors to copy, which means that he didn't really become rich, even though the process became widespread. That became the primary way of providing ice to much of the world, until mechanical freezers were invented.
Captain Sili' I mean I don't picture greece being that cold, but maybe it did Idk , you're so smart and clever and beautiful, thank you I love you
Johnny thanx man , that was. Cool of you , I could have easily done that too but I'm lazy and fat af
The slight of hand is in thermal contamination between samples. Look to the zeroth law of thermodynamics. Mpemba effect is only observed when both hot and cold water are in the same freezer.
why do they use tap water in stead of RO/DI water? btw, mpumba? hahah!!!
+Potion of Kings Reverse osmosis cleaned or distilled water might actually not freeze at all. Click the annotation about super cooled water.
+Tjita1 Then why not add your own impurities? That way you can achieve a level of impurities present in tap water but you will know both samples have the same amount and type of impurities.
That's... not unreasonable..
+hellterminator indeed not a bad idea!
A whole lot of I don't know and suggesting random combinations. Great job guys.
N-th!
On a really cold day up in the north in my homeland Norway (and when I say cold, I mean around negative thirty degrees), you can take a cup of hot water, throw it into the air, and it will freeze before it hits the ground. This does not occur with cold water
surely hot water cant freeze as it has to cool down first?
here is the way i think about this question: Hot water has more temperature, thus its molecules give away more heat in order to cool down. Since stuff can't cool down instantaneously(or can they? i don't know. Haven't read any theories regarding this. Heat transfer should at least have some time function. May be it was explained under thermodynamics), it would mean hot stuff cool down at a slower rate than cold water. BUT WAIT. May be hot stuff cool down faster than cold stuff - this is the easiest to experiment, and should be done before we do any experiment with water. We can just take two pure solids for this experiment. Then we can use two cans of pure gas. And finally, we will move to liquid. Then to water.
Someone needs to put some supercomputer on this task and stimulate the whole thing, then try to reproduce it experimentally.
How did Aristotle say that in 4 BCE? Didn't he die 322 BCE? Did he come back from the dead?
4th century ... look first
Krasimir Ivanov look where? It says 4 BCE. Where does it say century?
Turn on annotations.
I did, and I still can't see it for some reason. Something's wrong here! lol
+Krasimir Ivanov He says "in the year 4 B-C-E". How does that imply 4th century?
The Mpemba effect is NOT about freezing water. It's about the cooling process of ordinary tap water in an ordinary freezer. You can easily make 2 time graphs ( one with a hot cup and one with a lukewarm cup ) and the graphs can INTERSECT. The intersection is the interesting thing ( that completely breaks modern theories ) and not the freezing time
That was a very interesting video in which you said absolutely nothing
impurities decrease the melting/freezing point (colligative properties). I understood it the other way around in the vid.
I think you are right and they got it wrong in the video.
Impurities act as "starting points" for the formation of ice crystals, this is why tap water freezes more easily than distiller water.
+Davide Ragazzon if the impurities are dissolved in the water, the meltingpoint goes down and if the impurities are dispersed and float around, then they can act as nucleation point leading to faster formation of crystals but don't change the melting point.
If you throw it into the air maybe the lower surface tension of the hot water allows it to spread out with more surface area allowing it to freeze faster
As a Canadian, when it gets down to -40 here, boiling water will freeze when thrown into the air, but room temperature water/cold water will not.
i've always heard that...and i never really understood why or how it was. Good to finally know i wasn't the only one.
1:42 This is like saying that water freezes faster when it's in a leaky container.
Logically speaking wouldn't hot water HAVE to freeze slower than cold water. If you're freezing hot water, it will eventually become cold water but by now, time would have past and the originally cold water would be more frozen than the hot water would be. Continue this pattern and the cold water will have to be more frozen than hot water.
Correct me if I'm wrong because I'm genuinely curious.
That's whats supposed to happen. But as he said, sometimes that happens, sometimes not.
Michael Furtado i think it has smth to do with Stephan Boltzman law that hot bodies lose heat more quickly than cold colder bodies...
There are a lot of variables but the main idea behind why hot water freezes faster than cold water is because of energy transference. Bigger difference in temperature... Bigger attraction and push towards an equilibrium but like I said, there are a lot of other variables.
Actually, impurities in the water make it freeze at a lower temperature. That is why people throw salt on roads during winter... (1:25)
Get two samples of RO water, add a quantitative amount of known impurities to each (to make freezing possible). Then heat one sample up and then freeze.
A video on ocean currents (It's Okay to be Smart) stated that a given volume of warm water contains fewer molecules than the same volume of cold water. Therefore, it should follow that a given volume of hot water should freeze first as there is less water to freeze. Then of course there is the time it takes for hot water to give of heat energy, etc., but in not in a lab, in in front of my TV
so why not take 2 distilled waters, one heated one not, super cool them and then add a catalyst for crystallization and see which freezes faster? also if it could be done at water level that would be great too.
I think it has to do with rate of transfer of heat, the higher the temperature difference between hot water and the freezer, there is an acceleration of rate of heat transfer due to higher potential difference.
***** no, it doesn't, hot water has higher entropy than normal water, when it is brought inside a system with low entropy, the water gets colder much faster, and it is carried on, since heat is continuesly removed. This depends on the volume of water against the freezing capacity. For lower volume of water, this effect is pronounced, while higher volume, the rates tend to be similar, after the hot water reaches the normal water's temperature, because rate of transfer of heat is low for higher volumes.
***** Think of it like this, an object is dropped from 10m, when it reaches 5m, drop the another one of same kind from 5m. which has higher velocity? The one dropped from 10m, hence it will reach ground first.
+Sidharth Satheesh Your analogy doesn't work. Both objects still have the same acceleration. It will take the same amount of time for the 10m object to reach the 5m mark as the 5m object will take to reach the 0m mark. Remember that we're trying to time them. If I dropped both objects at the same time and observed the 10m object hitting the ground first, then your analogy might make sense. The whole point Feynstein100 was making is that at some point the hot water will be at the same temperature as the cold water. At that point, its temperature gradient, which determines how fast it will cool down, will be the same as the cold water initially. What you're proposing is that there is some difference in the water that allows it to "remember" that it had a higher temperature at some point which will drive it to cool down faster. What exactly do you propose this difference is?
Okay, use pure water 100% H2O, then on an interval poke it with a needle to induce freezing (with a robot of course.)
Refine the timing so the needle is only added to the water near the freezing point, then see what water cooled to its freezing point fastest.
Basically the water has no impurities up until we want it to start freezing - and the small amount of Iron or silica from a steel or glass needle would add so few that the freezing points cant be far off.
Here's an experiment I propose:
You'll need 2 peltier modules, 2 steel cups(with a flat surface), 1 big liquid container.
Put the peltier modules under the cups, one of them upside down. Use something to keep it in place and use thermal paste if possible. Fill the big container with water. Stir it to distribute impurities. Fill both cups with water from the big container. Power both peltier modules and let them sit for a bit. Then turn them off and shove them in the freezer!
Really cool video!
dT/dt = -k(T2 - T1), which means that hot water can't freeze faster since once it cools to the same temperature as the cold water, it will start cooling at the same rate, at which point the cold water will already have cooled more.
+Jay Something Unless hot water has a bigger k value. Hmmmmmmmm
Impurities in water actually cause melting/freezing point depression, not elevation. This is why people spread salt when roads become icy. The salt (an impurity) decreases the temperature water will freeze at and prevents ice from forming. Therefore, hot tap water would have a lower freezing point than cold distilled water.
In addition to him being wrong, I'm not too thrilled with how he tried to explain why hot tap water would freeze faster than cold distilled water. He basically said "the reason it happens is because it just happens." What kind of scientific explanation is that?
+iamihop in explaining why hotter water with impurities has a higher freezing point than water without impurities (which it doesn't, see my first comment) he essentially says "water with impurities has a higher freezing point because it just freezes at a higher temperature." That is not an explanation, it is a reiteration. Not only is he wrong (again, water with impurities has a LOWER freezing point), but he attempts to make it look as if he is giving an explanation for has false statement when he is just reiterating the observation. This is misleading to people who have little to no science background because it makes him seem as if he knows what he's talking about when he doesn't. It would be like me saying "the sky is blue because we see blue."
Freezing point of liquids. Completely pure water with no nucleation sites can be brought down close to absolute zero without freezing. Completely pure water is physically (and maybe theoretically) impossible as there is no way to eliminate every single atom in a container except for hydrogen and oxygen atoms bound in water. The container itself has atomic imperfections which will function as nucleation sites once the water is cold enough (-10 C or so depending on a lot of factors). However, if you were to use a theoretically-perfect surface free of imperfections (such as a pure carbon container where all carbon atoms are bonded to other carbon atoms) and use this to hold the theoretically-perfectly pure water then you could get the water very close to absolute zero before it would freeze. However, once the water and container are close to absolute zero quantum weirdness gets involved and everything we thought we knew about physics goes out the window. Because we don't live in a theoretically perfect world with perfect pure water or perfect containers freezing has more to do with the level of impurities and imperfections than the average molecular motion of molecules (temperature).
Lol, That dang water, so mysterious!
Water does not freeze on it's own. Ice crystals require a nucleation point to form around. Tests should control for how different impurities are introduced into the water while varying how much boiling is taking place.
I assume that how the impurities are distributed is the cause of the cascading effect.
Well with hot water the particles move faster. So it probably has a bigger chance to meet a slow moving particle so the temperature will balance out more quickly. My theory probably filled with holes
+Gabriel Tzukishiro he's using the word colloquially. Everyone knows what he meant...
A theory does not have to be true. then it would be called a fact, right?
+MrMellek Like swiss cheese.
Aparetly so simple... I'm puzzled about all the complexity behind! I'll think about it...
Could it be that hot water dissolves more impurities from the tap/pipes/container it's in?
i think this happens because the heated container melts the ice you put it on and comes in contact with the steel in the freezer and that way it freezes faster due to faster heat transfer because of the touching while the cold container sits on the ice which is a good heat insulator and therefore takes longer to give off its heat
I would think it would be caused by the conduction of the heat to the container it is in. the hotter water has a greater temperature thus heats the container more/faster, thus cooling the water off faster. my question is however, regardless of the actual freezing point, this means that the hot water is actually loosing more heat per time then the cold water, yes?
I thought this was just some old wives tale I heard about growing up. My parents taught me to always use hot water to make ice. Later I quit caring, because it seemed nonsensical. I had no idea it was actually an unknown.
fantastic video...
If you can't use two samples of water for them being different, Why not simply repeat the experiment with the same water in the same sealed container and time how long it takes? Boil the water first, put it in the container and seal it, then measure. Then take the water out, allow it to melt and warm to room temperature, and then refreeze it again. Maybe even use some kind of stirring (magnetic stir-bar?) to keep impurities always evenly distributed?
There's a Newton Law that predicts that the rate at which something cools down depends exponentially on th difference of temperature between THAT something and the environment, so this could be a plausible explanation. I have tried this in the laboratory with some hot crisols and it really worked: crisols who were in the oven at 400°C cooled faster than those at 150°C
When you heat up water, you give the water molecules more energy. They start moving around faster and faster. So, when you cool down hot water and cold water to the same temperature to make ice, the hot water already has some molecules moving really fast.
When you put both hot water and cold water in the freezer, the hot water has more of these fast-moving molecules. This means that hot water starts to freeze faster than cold water because it's already got some molecules that are moving towards becoming ice.
It's kind of like having a head start in a race. The hot water has a bit of a head start because some of its molecules are already moving fast, so it can turn into ice faster than cold water.
Isn't that cool? Even though it might seem weird, it's just how the tiny particles in water behave!
I reproduced this experiment 9 times, each time the cold water froze quicker, under different conditions as well.
I came across this experiment in a science fair idea book back in 4th grade (2003 or 2004) and got these same results. My teacher gave me a "P" for pass in the E>S>P>N grading, and her reason was that she thought I controlled the experiment wrong because my results didn't make sense to her. I hypothesized 2 of the reasons actual scientists have (obviously less clearly) about why I thought my hot water froze faster all 3 times (one was sealed). Convection and frost melting, I just didn't have the resources then to know what I was talking about.
I looked more into it now after seeing this video and am "P" for pissed off. The old cow's last name was Windberg but everyone called her "Ms. Windbag" outside of the classroom. I felt bad about it until now...
I always just figured hot water froze faster because the faster moving molecules spread the energy around a lot more, so even if the evaporated water doesn't go anywhere, it transfers energy away that in cold water would have to spread to the... Stuff around the water, slower.
Then again I'm not in physics, I'm in biomedicine.
Uhh, hot water is capable of harboring more dissolved gas than cold water of the same impurity concentration whether that be salinity or heavier elements like copper. William D. McCain Jr. proved this in 1990 and published it in his book 'The Properties of Petroleum Fluids 2nd Ed.'
1:22 "Hot tap water will freeze before cold distilled water... because impurities in the tap water means that it freezes at a higher temperature." I think you have that backwards. We salt the roads because the ions mixed in the water lower the freezing temperature.