h a l f b a k e r yRecalculations place it at 0.4999.
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Amidst searching to see if my newest idea was half-baked or
not I came across 'Evactuated Ice Cubes". It's kind of close
to
this, but really different and serves a different purpose.
Basically: An ice cube tray that bubbles air into each ice
cube
as they freeze. So we have ice cubes
with air bubbles in
them. Put it in your drink and they pop/explode
open. Increasing the surface area of the ice and cooling
your
drink (and you) faster.
Not meant to replace normal ice, just used for those really
hot days.
Close
http://www.halfbake...uated_20Ice_20Cubes
[swimr, Oct 04 2004, last modified Oct 05 2004]
A sealed ice cube system could work something like this:
http://www.funforal..._popping_thing.html
[Amos Kito, Oct 04 2004, last modified Oct 05 2004]
Prince Rupert's Drop
http://www.cmog.org/index.asp?pageId=735
Exploding glass [Aq_Bi, Jan 25 2005]
[link]
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(responding to original idea of high-pressure bubbles due to air temp warming - I'm leaving my comments because the original idea was interesting, if incorrect) |
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The problem is that the temperature of ice doesn't change as it's melting, and it melts at the same temperature as it froze. Unless you froze the ice at a much different pressure than you are melting it at, your bubbles will be at atmospheric pressure when the ice melts. |
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Right. But you have to look at what temperature the air was when the ice froze: 0°C (32.2°F). Then look at the temperature of the air when the ice melts: 0°C (32.2°F). So although air compresses quite a bit when it's colder, it's not colder. |
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I'm with [World] on this one. |
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um, I always thought my freezer was a little colder then
that but ok. I just tested this by looking for the ice cube
with the biggest (any) bubble at all. It cracked a corner
clean off. I'm not an engineer or anything, and in fact I
just woke up. Why did it crack open and how can I
duplicate it? |
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Yes, your freezer is colder than that, but ice freezes at 0°C (32.2°F). It's actually the basis of the Celcius system - ice freezes at 0 and boils at 100. They decided to use this as a temperature measurement system because it's easy to measure and doesn't change (assuming air pressure at sea level). |
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Now, why does ice crack when you put it in water? Because it's brittle. When you put ice in water you create a thermal gradient. Assume the ice is at -5°C. Putting it in water, the surface of the ice approaches 0°C, but the center is still near -5°C. Since 0°C ice takes up a little more volume than -5°C ice, there is now a pressure across the cross section of the cube. This often results in cracking, especially if there is an imperfection such as a bubble. |
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How do you duplicate it? Your idea might work. But not because of a difference in pressure. Note that I haven't voted against it. I think foamed ice would be neat. |
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OK, I understand now, thanks! Now this makes sense, and
now it's time to delete my earlier anno. |
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[World]'s explanation is correct - you actually have a stretching ice cube, rather than one that explodes. It's still pretty cool. |
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Now, if you wanted an *exploding* cube, all you'd have to do is figure out how to heat the air in the central bubble. We'd all beat a path to your door for that one (and anyone who says, "Convergent laser!!!one!1!" should be more original). |
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Hydrogen and oxygen mixture filled bubbles? Just add laser ignition. The great part is that the reaction will just yeild water (well, and heat but let's ignore that for now). |
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Of course, the next step is to have a cool flaming drink. High-proof liquor on hydrogen ice. Light liquor. As hydrogen ice bubbles burst, bubble rises to surface and light into small fireballs. |
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There was a company in the seventies that imported ice cubes cut from glaciers in Greenland. As they had been frozen under some pressure for hundreds of years, they would shatter satisfyingly when dropped in your gin and tonic. I can neither buy them nor Google them, more's the pity. |
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I wonder if the stress in the ice could be increased by freezing it very quickly, rather than the quite slow rate in a domestic freezer. Then maybe it would crack more when dropped in your drink.
To freeze more quickly, prepare very salty water in the freezer section. Hopefully it should not freeze. Then use an aluminium ice cube maker with normal water, and dip it into the brine. |
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Excellent idea, [Ling]. A saturated solution of brine should freeze at -21 degrees C, so it would stay liquid in any normal freezer.
There's a possible extension to this, although I'm not sure whether it would work or not. Put an unsaturated solution into the freezer compartment. Wait for it to cool down to the temperature of the freezer. Then add more salt. I think it should get even colder, allowing you to freeze your cubes even quicker. |
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Try "plastic ice cubes" -- hollow sealed cubes of water. Design them with air pockets and popping "buttons". Have the pressure balanced so well that freezing can set the buttons, and melting can pop them. You may use a gas in the sealed cubes that expands faster & with more volume than ordinary air.
Now your face can be splattered as badly as the sloppy athletes in Gatorade commercials. |
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//faster & with more volume than ordinary air// (sigh) Too bad ice melts at the same temperature it freezes, so whatever crazy properties it has at other temperatures doesn't matter. See discussion above. |
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//crazy properties//
That's right. Expanding ice may overwhelm contracting gas, anyway.
If you can't use heat as a trigger, use the water. Each plastic ice cube can have a spring mechanism. Freeze them solid, then set the spring on each one (maybe freezing can set it?). As the ice melts, it occupies less volume and transforms to liquid water. This moves the spring trigger, and causes the cube to "pop". |
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Ok, that I like. Though I'm not sure I'd want to end up with a bunch of plastic bubbles in my drink. |
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Sometimes my ice cube would explode on contact with the drink when I was a kid. Just POW and it would fly in half. I thought it was the greatest thing ever. I would hope it would happen every time I put ice in a drink. I noticed a correlation with the temperature of the liquid and the likelihood of detonation, the hotter the better. This event was most likely to occur on days so hot the cold water tap ran hot, i.e. the days I most needed ice, so it worked out pretty well. |
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Give me an option for a cold water detonating ice cube, and I will be eternally grateful. |
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[GPL] Turn your freezer down. You'll have a higher thermal gradient, and if cold enough have every glass of water be an ice popping experience. |
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Or drink from the glass you put it in. |
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Hmmm... Liquid nitrogen would freeze a tray of ice cubes REALLY fast... |
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In the name of science, I tried it. Liquid N2, distilled H20, and a little "ice cube mold" I made of parafilm (in retrospect I should have used foil). |
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Things it did:
1. Froze the everloving fewmets out of my fingers.
2. Froze too quickly (unevenly?) to form a coherent crystal.
3. Shattered as it was freezing. |
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Things it did not do:
1. Explode when dropped in room temp. distilled water. |
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Back to the drawing board, guys. |
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P.S. I have a -80 degree celcius freezer, do you think a cube formed at conventional freezer temperatures (-4 C) would benefit from being cooled in it? Or should I start with room temp water to acheive a more stressed crystal? |
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You don't want it to be pre-stressed. Ice isn't that strong and you'll likely shatter it as it forms. Start with freezer ice, and perhaps surround it by an insulator (such as a towel) to let it slowly reduce to a very cold temperature. With luck it won't shatter on it's way to -80. Now drop in normal water. |
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That's something to do at work tomorrow anyway. |
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I like [wagsters] comment about the imported ice.
Basically it's ice that was froze under high pressure.
Would this be a practical form of getting it to explode/
shatter? My only concern is whether or not the pressure
needed would be too great for the ice to freeze in a
household freezer. |
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Ice cubes often have a pressurized air bubble. It comes from air dissolved in the water that is excluded from the forming crystal. Cooled slowly and evenly the ice forms a shell on the outside first as clear ice, the air and other stuff are driven toward the center. Water will dissolve about twice as much air when cold than at room temperature, so letting water stand in the fridge long enough to become saturated before freezing would improve the explosions. |
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Hey, I hate to play trogolodyte, but what's the real goal here? As I read it, swimr wants to "cool your drink faster" "for those really hot days". Why is the explosion part necesary at all? |
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One way to increase cooling is just use smaller ice cubes. I used to have a plastic ice-cube tray that made *tiny* little ice cubes. It worked nicely. |
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Then there's the "slushie" or "slurpie" or "margarita" effect... sand-sized ice grains that can freeze your brain quite effectively. |
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You could also use so called phase-change materials such as "eutectic" salts that absorb more heat than ice in order to exhibit a phase change, perhaps encased in a high thermal conductivity material, such as silver-plated copper. |
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But it's not clear to me why the "exploding" part is necessary. |
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[musicator], you're right, of course. But it is so satisfying to drop an ice cube into a drink and then hear a big cracking sound. Don't ask me why.
Perhaps it's the same reason as why crisps are crunchy.
By the way, perhaps [Worldgineer] is right, and the best way to get a good crack is to freeze the ice very slowly. I've noticed that some cubes don't crack, and others do, even if they are frozen in the same batch.
Definitely room for experimentation....Effect of dissolved air, size of cube, shape of cube and so on. |
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Leading of course to the invention of the shape charge ice cube tray. |
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If the popping is caused by stress fractures, you can manufacture the ice in a way that maximizes this stress. Make a sandwich of ice layers, each frozen at different rates. The ice then shears as it contracts. The final shape is important, maybe a "waffle" shape covered in sheets of ice would fit the idea -- cooling faster as ice melts.
A specialized machine can build the popping ice cubes for you. |
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Well, flash-freezing does prevent the formation of ice crystals...that's why it's the preferred method of tissue-prep the world round. |
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I'm in favor of the whole slow-freeze-in-a-normal-freezer-then-toss-it-in-something-much-colder method. |
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[GutPunchLullabies], you were on the right track. This idea is very similar to tempered glass. Tempered glass is made by quickly cooling near molten glass. This puts enourmous stress on the glass, but as long as the outer layer is intact, it will not break. |
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By trial and error, you could get the water to freeze in the same way as glass. Once the outer layer has melted, the ice will explode like tempered glass. Just like Prince Rupert's drops. [link] |
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Of course, [GPL] hasn't been around in a while. I wonder if this fact has anything to do with these experiments? Is s/he somewhere right now in a -80 freezer with ice crystals embeded into the walls? |
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Wanna' see ice explode? Drop a cube in a deep fat fryer. Oh, do it from distance. |
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I guess it's not, technically, the ice exploding but it sure is ferocious. |
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So ferocious in fact that it would be a really bad idea to do it anywhere other than a "what not to do" advisory. |
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Shake the tray about half an hour into freezing. You want to see an ice layer on top, and an airbubble forming underneath. This will give you all the 'sploding ice you want. |
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After my own practice, I believe I have concocted a relatively easy way to do this:
Put a stopper in the bottom of an ice cube tray. Drill a hole for the stopper to go into first, of course. Pour in water. |
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After the edges of the cube have frozen, turn the tray over and pull the stopper out. |
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Insert a heated nail through the hole in the tray and into the ice cubes. Turn them over and drain them for a few moments, though not until they are completely devoid of liquid water. |
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Re-insert the stopper. Re-insert the tray, allow to finish freezing. |
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Gravity will pull water back into the cavity you've made, increasing the amount of free air, but also allowing for a strong bottom. This will lead to a larger explosion when the critter ruptures. |
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Another idea: Make an ice cube with a chunk of solid CO2 (dry ice) in the center of it. The CO2 will slowly change to gas, even while at the freezing point of water, thus making a pressurized cavity in the center of the cube. |
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Granted the pressure might get too high and blow up the cube prematurely. In that case, use a small piece of CO2 that doesn't completely fill the cavity (I have some clever ideas on how to do this). Then the pressure won't get so high. |
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You'll want to make very sure the CO2 completely sublimates though. Swallowing a chunk of still-solid CO2, even wrapped in ice, is hazardous to your health. |
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I see the way we are going with this. At first we tried to get a satisfying 'crack' from the ice cubes. Now we are blowing up the glass. Next on the list... exploding ice-cube proof glasses and handling tongs. |
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Somebody mentioned dissolved gas bubbles as being a likely culpret. Has anyone tried freezing up a tray of seltzer water? |
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That can be done, but you get a foamy ice. It'll be more of a continuous, Rice Krispies-style snapping than a good satisfying crack. |
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I've had canned carbonated water freeze. Sometimes the cans explode quite violently. I'm guessing the CO2 is forced from solution when the water freezes, increasing the pressure. I don't remember what the ice was like though. |
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