Skip to comments.RSC offers £1000 for explanation of an unsolved legendary phenomenon
Posted on 06/27/2012 12:41:32 AM PDT by neverdem
It seems a simple enough question - yet it has baffled the best brains for at least 2,300 years.
Now the Royal Society of Chemistry is offering £1000 to the person or team producing the best and most creative explanation of the phenomenon, known today as The Mpemba Effect.
Competition judges will be looking for an outside-the-box, inventive submission. In addition, the format of the submission should be creative and eye-catching.
Any medium or technology can be employed to make the case, including articles, illustrations or even film.
Submissions can be based on, and reference, existing research. The winning submission will be scientifically sound, and arresting in presentation and delivery.
The public has four weeks to crack the case before a group of the world's brightest young science brains take on the challenge in London as one aspect of a special science communications meeting entitled Hermes 2012.
Fittingly, that group's bid for glory will be made in the first week of the Olympics. The sharpest international postgraduate science students will travel to England from around the globe to participate in the Hermes 2012 event.
The Royal Society of Chemistry is sponsoring this visit to the UK of the hand-picked young scientists, who will gather at Cumberland Lodge in Windsor Great Park...
(Excerpt) Read more at rsc.org ...
Because G_d made it that way.
In fact, only The Lord knows. Ask Bacon or Aristotle or even anyone living.
This 'contest' is an effort to render objectivity as evil.
Close; but one of my courses in Chemical Engineering explained it so many years ago.
Now where do I collect my prize?
Every once in a while I would answer my geology or physics exam questions with that if I had no clue. Never worked though - although it is the truth!
How did anyone prior to refrigeration know that boiling water freezes faster than cold water?
I think the mythbusters busted that myth btw.
FReepmail me if you want on or off my health and science ping list.
One things for certain, if it didn't we'd all drown.
The two most volatile elements, put em together and they kill fire. Without chlorine life as we know it wouldn't exist either. Oh but it's all randumb chance, and accidental.
Why does ice float?
I did not know that. I honestly did not know that.
The Mpemba Effect, good one... cold water is more dense, so there’s more of it from which to remove heat? Oh wait, that doesn’t work, water is one of the few (or the only?) material which increases in volume as it approaches the freezing point (hence, ice floats), and as the temperature continues to fall in the ice, *then* starts to shrink.
For 40 years I've been told that the "hot water freezes faster" thing is a myth.
I feel that this "contest" is meant to be a joke.
Here's a summary of the Wikipedia explanation:
The oxygen atom in each water molecule attracts electrons more strongly than the hydrogen atoms, so the hydrogens have a slight positive charge. This allows water to form "hydrogen bonds" in which the positive hydrogens are attracted to the negative oxygen atoms of other molecules.
Each hydrogen can form a hydrogen bond with another water molecule and each oxygen can bond with two hydrogen atoms, so altogether one water molecule can have up to 4 hydrogen bonds with other water molecules. In an ice crystal there is a lattice of water atoms held together with these "hydrogen bonds".
The hydrogen bonds have a certain length that holds the water molecules in position at a certain distance apart from each other. As the ice is heated and melts, fewer hydrogen bonds can form, the lattice structure breaks, and the water molecules are allowed to come slightly closer together. This causes liquid water to have a lower density.
Because of the down hill slide effect.
Now send me my money. . . . .
That was what i was taught too, except that liquid water has a higher density, not lower, compared with ice.
If I remember correctly, water is at it’s densest at about 39 or 40 degrees Farenheit. The surrounding water around the ice is about or near that temperature. Lowest specific gravity always floats, while highest sinks.
The specific gravity of water goes down until 39 or 40 F, 4 C. Then it goes slightly up until 32F or 0C where it stabilizes.
Same reason a boat floats: the ice has a greater volume than liquid water, so it's less dense than the same volume of water. An object that is less dense than the water it displaces is forced upward, i.e., is bouyant. Young engineers at Old Dominion University are given first-hand experience in this effect in their annual Concrete Canoe contest.
What that whole essay seems to be saying is that the hot water freezing faster is an illusion, caused by other factors which act upon the water.
Apparently, quite a few things need to be controlled in order to test the hypothesis that hot water freezes faster. The water must be degassed (to control for the change in freezing point caused by solutes). The water must be prevented from evaporating, which causes other complications—hot water can only be prevented from evaporating by putting it in a container that does not expand, and preventing it from expanding increases the pressure, and increasing the pressure increases the freezing point. So the cold water would have to be subjected to the same pressure. The water must be cooled slowly, so as to avoid the supercooling effect. And the water should be stirred to maintain an even temperature—but the stirring will lower the freezing point—although this may not be necessary if the cooling is sufficiently slow to prevent supercooling.
I remember doing crystallization studies back in undergrad chemistry classes. We had to put crystals into a tiny glass tube, and put the tube into a heater that took forever to heat. Then we sat there, looking through a magnifier at the crystal until it started to melt, and record the temperature. As I recall, the temperature change had to be very slow to get an accurate reading.
I also recall from those chemistry classes that a pure substance has to spend some time at a particular internal temperature before it undergoes a phase change. That is because the substance must gain or lose internal kinetic energy (depending on the direction of the phase change) before it can undergo the transition. Once the energy is gained or lost, the phase change occurs fairly rapidly.
Okay. 'series'. I was gonna say what you did neverdem, but in a simpler way.
Kinda like hot water molecules = car going 100 mph and hitting a concrete wall, vs a car going 10 mph and hitting the wall. The 'wall being Ice' in the case of water. And mph = molecular 'speed'.
I haven't had to use that stuff since I learned it around 1975. Then forgot it as soon as I could thanks to those personal computer thingys and MS programs from that nasty and evil Bill Gates guy.
"But by the 20th century the phenomenon was only known as common folklore, until it was reintroduced to the scientific community in 1969 by Mpemba, a Tanzanian high school pupil. "
Something about this rings false to me. In 1965, a high school teacher of mine challenged me to do this same experiment at home, in private conversation with him. Later on that week or maybe a month later, he extended that same challenge to others in my class. So, somehow it was not "reintroduced to the scientific community" by someone who lived in Africa, but was apparently widely known in America.
By the way, no one who did the experiment found that hot water froze more quickly. The teacher laughingly explained that it success was more an effect of poor housekeeping -- that hot water melted ice/frost in the freezer, allowing the container more intimate contact with the freezer coils.
Look at your line going to your icemaker in your frige——bet it is hooked up to your house hot water line. lol
My guess would be that it involves the amount of adsorbed gasses in cold water as opposed to hot water.
Heating the water over an extended period drives the adsorbed gasses out. So cold water will have more gasses adsorbed in it.
Adsorbing a gas in water lowers the freezing point. We’ve all seen this with a can of coke that’s very cold but still liquid, and when you pop-the-top and let some co2 out it immediately freezes.
I once heard on a science radio show that evaporation (aka, less mass to freeze) is the key to the story.
Warm water makes for less cloudy ice cubes.
“Warm water makes for less cloudy ice cubes.”
I didn’t know that, but probably the same reason... less devolved gasses. You could test this by putting the cold water in an ultrasonic cleaner first. This will drive the gasses out.
Because if that we not true, life on this planet would probably not have been possible. The fact that ice floats is incredibly important. I've always found it fascinating that water is one of only a couple of known substances that are less dense as solids than they are as liquids.
That's pretty much what I thought as well, mainly because of the clarity of the ice you get with hot water, as opposed to cold, although I think the speed of freezing also has something to do with how cloudy ice is.
Stand back folks! I'm going to attempt ... science!
Whoever he was.
Hint: It’s related to the fact that water takes longer to boil if you stand there and watch it.
RSBC offers £1000 for explanation of an unsolved legendary phenomenon
Royal Society of Body Chemistry ^ | 26 June 2012 | NA
Posted on Wednesday, June 27, 2012 3:41:32 AM by neverdoneit
Why does a hot woman warm up faster than a frigid woman?
Note to self: When doing technical writing at 3 AM, expect to make glaring mistakes.
The layman’s version of wideminded’s answer: Because H20 in it’s solid form forms hexagonal crystals. Any lattice structure is always going have more surface area for the same mass as a non-latticed structure. What made you think this was unknown?
Sometimes, some places, it gets cold enough to freeze water even without refrigeration. Besides, you can make ice in cool temperatures that are way above freezing. The Romans did it in antiquity.
Isn’t this a test by the Royal Society, to see who is dumber?
The general public or their students ?
A new ‘evaluation’ method, perhaps?
Or is the Royal Society training their students to accept ‘academic’ knowledge (the belief that hot water freezes faster) without question?
If you put two identical ice trays, filled with exactly the same amount of water, at the exact same temperature, in the freezer, which one will freeze first ?
If you look at the water molecule it is ‘lopesided’. When heated, a body of water tends to layer thus tends to align the lopesidedness, allowing a faster crystalization when the temperature drops.
I like your answer best.
Hot water freezes faster than cold water for the same reason that global warming e-mails keep getting changed by outside forces when subject to observation by discriminating minds.
That's part of it. Evaporation itself causes cooling, which is another part.
I remember trying to test the old wive's tale as a kid, by putting a tray of cold water and one of hot water in the freezer at the same time. I don't know which froze first, but the hot water tray only had half sized icecubes.
Maybe I’m stupid, but I still don’t get it. Please help me our here if you would. Thank you.
Let’s say I make a canoe out of solid ice and a canoe out of solid concrete, then drill a 6” hole in the bottom of each.
Which one will meet with the bottom of the lake sooner?
The ice canoe will still float. The concrete one will sink faster than....well, a concrete boat with a 6” hole in the hull. I am aware of boats using concrete hulls.
Remember those little ice cubes that had hole in the middle? They floated.
I’m not trying to be sarcastic or mean, just realistic, IMHO. Please correct me if I’m wrong.
Phooey. It is not the case with other molecules.
After reading all that, I’m now more convinced that it DOES have something to do with the lopsidedness of the water molecule and the easier crytalization of a more uniform molecular array. What other molecule has the unique property of water that it is expands to reduce density when frozen?
After reading all that, I’m now more convinced that it DOES have something to do with the lopsidedness of the water molecule and the easier crytalization of a more uniform molecular array. What other molecule has the unique property of water that it expands to reduce density when frozen?
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