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Have you heard of "The Mpemba Effect"?

Tommy 2012/07/31 13:38:03
Calling all budding Physicists!

Scientists have been offering a prize of £1000 ($1,566) for an answer to the question:

Why does hot water freeze more quickly than cold?

The article was contained in British Newspaper The Daily Mail and a link to the page is shown below.

Unfortunately the closing date was July 30th, 2012, but that does not stop you from having a go!

Read More: http://goo.gl/9VOon

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  • harristotle 2012/11/04 09:59:24
    harristotle
    +2
    mpemba effects mpemba effects
  • harristotle 2012/11/04 09:46:20
    harristotle
    +1
    Join the discussion. Express your opinion.
  • Dave Sawyer ♥ Child of God ♥ 2012/08/10 16:20:35
    Dave Sawyer ♥ Child of God ♥
    +3
    Because water expands when it freezes, and in hot water, the molecules are already farther apart, so freezing requires less energy to be transferred.

    freezing hot water
  • Tommy Dave Sa... 2012/08/10 16:31:51
    Tommy
    +1
    I don't think I follow but that is probably my fault. Presumably water will not freeze until its temperature is lowered to zero Celsius? If that is the case, then surely it is no longer 'hot' water? I hope that makes sense.
  • Dave Sa... Tommy 2012/08/10 17:01:52
    Dave Sawyer ♥ Child of God ♥
    +1
    Then "hot" water can never freeze.

    But if you happened to spray hot water into frigid air, you would get the effect, and probably snow.
  • Tommy Dave Sa... 2012/08/10 20:46:19
    Tommy
    +1
    I have seen hot coffee thrown out of a mug in a very cold place - cannot remember where now but I don't suppose it's too important. Anyway, the coffee trail froze almost instantly into either ice or snow. It was amazing. I did wonder at the time: what if that had been cold water instead of hot coffee?
  • Kozmo Tommy 2012/08/10 20:23:35 (edited)
    Kozmo
    QUICKIE!!!

    As said above water can exist in a 'supercooled' state until it's shocked, has anyone explained that? May be connected with Mpemba.
  • Kozmo Dave Sa... 2012/08/10 20:23:58 (edited)
    Kozmo
    I've mention the Hydrogen Bond (q.v.) as a factor. Water is most dense at 3.7°C as it cools further, it expands. When a particular amount of water is liquid at 0°C, it must shed Enthalpy (Heat) of Fusion (almost as much as raising the same water from 0 to 100°C). I notice on you provided graph, that the Hot water got down to 0° faster (my 'Momentum' hypothesis alluding to Entropy) but once there took quite much long to to solidify. A Mystery to me.

    [Digression] The Enthalpy of Vaporization explains why hot steams causes such bad burns, when it condenses on the skin, it releases (even more than melting) huge amount of latent heat.

    [Re·Integrate] The weather phenomenon of Sleet (or freezing rain) is the raindrops have supercooled below 0° but when they land on something, the shock of impact causes them to glaze whatever they hit. Looks like some sort "Thermal Inertia Effect" is working here.
  • Bastion 2012/08/10 13:00:32
    Bastion
    +1
    Lively molecules are more prepared to line up in a pattern.
  • lurx: the soda jerk 2012/08/10 12:34:56
    lurx: the soda jerk
    +1
    Water Freezing and Boiling Myths

    Hot water freezes faster than cold water. Most experts say that, all things being equal, cold water freezes faster. However, things are not always equal. A curious phenomenon known as the Mpemba effect can, under some very specific (and poorly understood) circumstances, result in hot water freezing faster than cold water. One of the several possible explanations for this effect involves evaporation: if you start with extremely hot water, a good bit of it will evaporate (and a smaller quantity of water will freeze faster than a larger quantity). And so, according to chemists, this one is not a myth, and this is presumably what my high school chemistry assignment was getting at.

    http://itotd.com/articles/521...
  • Tommy lurx: t... 2012/08/10 15:38:22
    Tommy
    +1
    I don't think the point is 'DOES hot water freeze more quickly than cold?' The assumption is that it does because it has been demonstrated over and over. The question is 'WHY does it?'. I read about the evaporation theory and I'm not convinced that it holds water. If it were down purely to the quantity, then surely it would level the playing field to ensure that there is a little more hot water that there is cold? I also am sure that if the explanation were as simple, then it would not have baffled scientists since the 1960s.

    Thanks for your submission. :-)
  • Kozmo 2012/08/08 16:21:59
    Kozmo
    +1
    Hot water is in a higher energy state than cold so there's more kinetic activity. I think Radiation of Heat goes up to the 4th power of the differential. By way of Convection is similar but a different curve. Conduction is likely similar too.

    Perhaps there's a 'Momentum Effect' that lags a bit behind the cooling of the fluid.
    Water also is also densest at ~3.7°C & the reason why Ice floats is that it's less dense (unlike almost all other material, Type Metal an exception).
    This is because of the Hydrogen Bond. The hydrides of Oxygen's neighbors on the Periodic table (N, C, F, Si, P, S, Cl, Ge, As, Se, Br, Sn, Sb, Te, i, Pb & Bi) are gases at Room Temperature (20°C/68°F) because the H-bond is too weak or doesn't bind as well to keep these substances as liquids there.
  • Tommy Kozmo 2012/08/08 16:39:53
    Tommy
    +1
    This is very impressive! Thank you for the submission. I like the concept of the 'momentum effect'. I assume the (topical) analogy is that the sprinter (Eusain Bolt) will pass by the long distance runner even though the sprinter started further back in the field?

    There are some experiments that, given access to a lab and equipment, I'd love to try out. I'd like to submerse accurate thermometers in two beakers of water, one hot (say 60c) and one at room temp (say 20c). The readouts for both would be on a computer screen and the beakers placed in a deep freeze. I would record both readings say every minute and observe the possibility of the momentum effect taking place. I would be very surprised if this has not already been tried in some shape or form since the '60s!

    Thanks again - first serious answer!
  • Kozmo Tommy 2012/08/09 08:59:32
    Kozmo
    +1
    Seen posted on an office coffee machine:

    Do not move, it may disturb settings - Engineers

    attached below was:

    Do not look at, it may change Quantum States - Physicists

    After seeing this, I came up with a hypothesis for "A Watched Pot Never Boils" using Quantum Principles. When one looks at such a pot, "spooky action" occurs & the cerebral-spinal fliud in the viewer's head instead goes exothermic.
  • Tommy Kozmo 2012/08/09 10:38:53
    Tommy
    +1
    LOL - Amusing, if a wee bit less scientific!
  • BeerJingle 2012/08/08 00:34:33
    BeerJingle
    I've heard about the mixing juice and milk effect.
  • Tommy BeerJingle 2012/08/08 02:11:30
    Tommy
    And what happens there? Anything special?
  • BeerJingle Tommy 2012/08/08 03:07:35
    BeerJingle
    +1
    about 9 hours of stomach aches.
    And a morbid fear of juice for about a week.
  • Tommy BeerJingle 2012/08/08 09:06:05
    Tommy
    Oh dear! Well, perhaps not the best mix!
  • BeerJingle Tommy 2012/08/08 09:30:36
    BeerJingle
    +1
    I learnt the hard way....
  • Kozmo BeerJingle 2012/08/08 16:24:50
    Kozmo
    +1
    (Often) acidic fruit juices will curdle Milk in the stomach.
    Do you have an aversion to Cottage Cheese?
  • Tommy Kozmo 2012/08/08 16:45:00
    Tommy
    Mixing fruit juice and milk should not have had this effect. I suspect that there was another coincidental reason for the stomach aches and the mixture was (wrongly) blamed. It reminds me of the guy that drinks ten pints of beer, then eats a pie and then throws up. He blames the pie and suggests that it was stale. Uh hu!
  • Kozmo Tommy 2012/08/09 09:02:14 (edited)
    Kozmo
    You last sentence is easy! It's a combination of "the last straw" & projective denial. Been there, first time I drank 10 beer & had half a bucket of KFC. When I went to bed & lay on my back, I puked, lucky I didn't choke.
  • BeerJingle Kozmo 2012/08/08 22:20:58
    BeerJingle
    +1
    Nope, I was eating chedder at the time.
  • Kozmo BeerJingle 2012/08/09 12:13:17
    Kozmo
    Aged cheese has MAO Inhibitors, so do ALL fruit. Perhaps it was a serotonin spike, being on anti-depressant exacerbates, potentially lethal. people attempting to "trip" on Ayahuasca (uses two plants, on with DMT, the other with MAOI's) have to be careful what they eat for up to a fortnight beforehand.

    The symptoms are often described as a clinical triad of abnormalities:

    Cognitive effects: headache, agitation, hypomania, mental confusion, hallucinations, coma
    Autonomic effects: shivering, sweating, hyperthermia, hypertension, tachycardia, nausea, diarrhea.
    Somatic effects: myoclonus (muscle twitching), hyperreflexia (manifested by clonus), tremor.

    Many MAOIs inhibit monoamine oxidase irreversibly, so that the enzyme cannot function until it has been replaced by the body, which can take at least four weeks.

    Does this sound close?
  • BeerJingle Kozmo 2012/08/09 21:24:09 (edited)
    BeerJingle
    +1
    SURE!

    But this happened in 2006, I was not on pills and Mao was the ruler of china until 1972 not the cause of my stomach ache.
  • Tommy BeerJingle 2012/08/09 23:48:58
    Tommy
    +1
    LOL

    (Monoamine oxidase)
  • BeerJingle Tommy 2012/08/10 07:31:00
    BeerJingle
    Oh.
    I am glad that the dictator of china didn't come for a visit then.
    Although that would have made the report I did a couple days ago quite easy...
  • Kozmo Tommy 2012/08/10 18:17:46 (edited)
    Kozmo
    There's a new Psychology Theory for Autism from Europe: "Caetextia" (context blindness) but it can affect anyone who's stressed out(& who isn't nowadays). Since I've heard of it, it explains quite eloquently why the World's going to Hades by making everyone a Basket Case.

    For Society - http://blog.humangivens.com/2...
    For Organizations - http://www.lornemitchell.com/...
    Original Psychology (nerdy) - http://www.caetextia.com/
    for small groups, check out any Sit-Com, it's exaggerated,
    but in the Real World, it's nothing to laugh about.

    Also, you're online when you're here in the Soda Headlands, can't you push a few keys or clicks & summon Google?
  • Tommy Kozmo 2012/08/10 18:29:23
    Tommy
    You have now challenged my brain to near its capacity. Does the above have any connection with: The Mpemba Effect, Vomiting due to mixing milk and fruit juice, or with Chairman Mao?

    I'd appreciate the clarification. :-)
  • Kozmo Tommy 2012/08/10 18:42:40 (edited)
    Kozmo
    +1
    Being Autistic, I have the 'scattered' (right brain) kind of Caetextia.
    A few entangled threads ("Inception" & "Premonition" makes sense to me):

    The MAOI reference was to your comment about mixing milk & juice
    The Caetextia was in reference to dude (mindlessly) confusing MAO with the late Chairman, just attached to links to read at your leisure, if so desired, but may elucidate why our Society seems Hellbent to dive down the toilet.

    My Mind (et al.) is a Hive of activity. Being Bless/Cursed with Asperger's (check out "Mozart & the Whale") my Thought Processes are a like a

    "Byzantine Machiavellian Rube Goldberg Gordian Knot" & I have a "Complicated Complicating Complex with Complications",
    if only Carl Jung (he coined the term Complex) were still alive.

    but being a former Cub & Boy Scout, I'm fairly good with knots,
    I'm also a Jungian. Follow Kierkegaard too.
  • Kozmo Tommy 2012/08/10 20:06:59 (edited)
    Kozmo
    +1
    Being Autistic, I suffer from the Dysphoric (Mixed) kind of Caetextia.

    You reference to mixing milk & juice sent me off on a tangent from the Mpemba Effect (being human, we ALL digress but I'm more prone)).

    The word play with MAO sent me into InfoMania Mode which pruduced the deluge of references to Caetextia (at least I only sent the links, others like me would post the entire articles(seen them on SH, since unfriended & blocked), so I've got some Restraint.

    I'm not DICTATING that you read the article (again Caetextia) but just suggesting you peruse them on your time, the two upper ones may elucidate why our Society seems to be Hell-Bent on creating more problems rather than solving them (some Theology [I'm a Deist] can explain that, another discussion for later).

    I've Realized that I'm some sort of (undiagnosed, had 3 three assessments over the last 2 years, all different, the Shrinks are clueless, or also afflicted) Asperger's (capacious memories) coupled with Complex PTSD which when done to US, leaves us with "Hyperthymesia" a "Phenomenon"al Auto-Biographical memory.

    I'm quite aware that my Thought Processes operates much like a

    "Byzantine Machiavellian Rube Golberg Gordian Knot" (Vista?)

    but being a former Cub & Boy Scout, I know a bit about knots. I also made it through the...







    Being Autistic, I suffer from the Dysphoric (Mixed) kind of Caetextia.

    You reference to mixing milk & juice sent me off on a tangent from the Mpemba Effect (being human, we ALL digress but I'm more prone)).

    The word play with MAO sent me into InfoMania Mode which pruduced the deluge of references to Caetextia (at least I only sent the links, others like me would post the entire articles(seen them on SH, since unfriended & blocked), so I've got some Restraint.

    I'm not DICTATING that you read the article (again Caetextia) but just suggesting you peruse them on your time, the two upper ones may elucidate why our Society seems to be Hell-Bent on creating more problems rather than solving them (some Theology [I'm a Deist] can explain that, another discussion for later).

    I've Realized that I'm some sort of (undiagnosed, had 3 three assessments over the last 2 years, all different, the Shrinks are clueless, or also afflicted) Asperger's (capacious memories) coupled with Complex PTSD which when done to US, leaves us with "Hyperthymesia" a "Phenomenon"al Auto-Biographical memory.

    I'm quite aware that my Thought Processes operates much like a

    "Byzantine Machiavellian Rube Golberg Gordian Knot" (Vista?)

    but being a former Cub & Boy Scout, I know a bit about knots. I also made it through the Canadian Armed Forces Militia Boot Camp despite this Altitude I'm "Possessed" with. I'm also studying Carl Jung to better understand myself. Just over 2 years ago I was a reticent miserable depressed 'stick in the mud' but I had one Mutha of a "Spiritual Awakening" and now damned to be an

    "Obstreperous Irrepressible Vociferous Orifice" (can be anything)
    but still mired in the muck but I'm now making tsunamis with it. If only
    Jung (suspected Aspie too) was still alive, he coined the term Complex. He'd like me to examine my head. I make an affirmation: I have a…

    "Complicated Complicating Complex with Complications"

    (wow wow)
    (more)
  • Tommy Kozmo 2012/08/10 20:42:01
    Tommy
    +1
    Thank you for the clarification! Your self-deprecation is worded in an amusing manner and I did enjoy reading it. That is not to say of course that I find the condition that afflicts you amusing. Not in the least. I did have an inkling about the condition called Asperger's but you have helped me with a personalised view of it. Enjoy the Jung. I hope it brings some enlightenment.
  • Kozmo Tommy 2012/08/10 20:52:00 (edited)
    Kozmo
    +1
    No offense taken, to paraphrase Mr. Spock
    (Gene Roddenberry [May He Drift in Space] was one of US!):

    "I (now) know how I think (& others) better
    (but imperfectly) than most others know themselves"

    "Benny & Joon" (Depp) alludes to it (eccentricity) &
    "Mozart & the Whale" (just saw last night) NAILS IT!!

    I like to stop this thread, you?
  • Kozmo BeerJingle 2012/08/10 18:22:47
    Kozmo
    +1
    Have you fully read my comment? (read the one to Tommy below too)

    MAOI's are found in a bunch of different foods so there could be a "last straw" effect. It's also found in Red Wine which may be why Wine & Cheese parties are popular, apparently with little risk, you just get a subtle 'buzz'.
  • BeerJingle Kozmo 2012/08/10 23:49:26
    BeerJingle
    +2
    Yeah I read your comment I am trying to be comedic.
  • Kingarthurup 2012/08/02 07:51:40
    Kingarthurup
    +1
    because of global warming
  • Tommy Kingart... 2012/08/02 10:10:00
    Tommy
    ha ha ha! Very good. It's probably Obama's fault too!
  • ray 2012/07/31 13:56:51
    ray
    +1
    Great post , never heard of the Mpemba effect . Thanks for the chance to learn.
  • Tommy ray 2012/08/01 01:20:58
    Tommy
    +1
    A pleasure, sir!

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