why water expands when it is cooled?
86483
Actually, Gonpatrick, the original question is quite correct: Unlike most substances, water does actually expand when it is cooled, over a narrow temperature range from about 4 degrees C to 0 degrees C (the freezing point.)  This is why water freezes from the top down: the cooler water that is closer to freezing is less dense than, and so floats above, slightly warmer water.  (Above 4 degrees C, water expands when it is heated just like most other substances.) When the water freezes it expands some more, which is why ice floats.\n\nThe reason why it does this has to do with the way water molecules are put together.  The two hydrogens and one oxygen in H2O are assembled in a triangular pattern, with one part of the molecule more positive and the other more negative.  Above 4 degrees C, the molecules move freely around each other, but when it gets close to its freezing temp, the molecules start to align themselves with the positive part of one molecule near the negative part of another, ultimately forming, when it freezes, a hexagonal pattern.  This arrangement takes up more room than when the molecules are free to move around.
770181
Because ice is less dense than water and thus take up more volume than equal amounts of liquid water. So when the water freezes in the pipe, the ice expands and the pressure from the expanding ice cracks the pipe.
955519
The density of a solid or liquid is determined by the various kinds of intermolecular bonds, see the reference.  These bonds tend to attract a molecule to its neighbors.  The molecules tend to keep getting closer until the electrostatic repulsion between the positively charged nuclei equals the attraction.\n\nAs you increase the temperature, nothing changes within a molecule, the molecules just move more.  In a solid, they generally stay in place and vibrate with respect to their neighbors.  The repulsive force is inverse square with distance, so as molecules get closer, the repulsive force increases rapidly.  Thus, the vibrations involve more movement away from the neighbors than toward the neighbors.  That's why the average distance between molecules increases with temperature.\n\nRarely, other factors dominate.  As water cools, it contracts until it reaches about 39 degrees F, and then starts expanding.
74872
I'm sure this isn't the only material with this property.  \nDo you know what a phase diagram is?  If the line between the liquid and solid phases has a negative slope (goes down as you read it across) like the second phase diagram at this website: http://wine1.sb.fsu.edu/chm1045/notes/Forces/Phase/Forces06.htm\nAny material with a phase diagram that has the line between the liquid and solid phases as a negative slope becomes less dense (expands) when it freezes.  \nThe reason that water expands when it freezes is because when water crystallizes into ice, the structure leaves this pocket of emptyness in the middle of a ring of water molecules.  This makes the ice larger than the water it was when it was liquid.  Anything else that does this will also expand.
913425
When the ice was floating on water, the water had lifted by certain level..tht level was equal to the weight of the ice..s when the ice melts , the water level wont increase since the water from icemelt is equal to the earlier weight of the ice ...and the water on which ice was floating had already risen to accomadate tht weight..so it wont rise again when the ice melts...
85146
When you freeze water it expands, which increases it's volume. With a closed bottle, the pressure gives the expanding water no where to go, therefore the bottle must expand with the water, making it explode.
549327
Freezing water expands.
194414
Water is denser than air and transfers heat more rapidly.
993848
Water is a very unusual substance. When it becomes a solid and crystallizes. The structure of the ice crystal become less dense and floats. The crystalline structure actually pushes the water molecules away from each other and thus expands. This is very unusual because water is one of the only (if not the only) substance that floats as a solid when it is within its on liquid (if that make any sense). So, in an unconfined area, such as a glass of ice water, you would see that the ice floats and rises above the water. In an confined area, such as a bottle, the Ice has no place to go so it expands the bottle. When you let a little of the ice melt and the is some water in the bottle, the bottle is still under pressure from the ice and the water will come out. To prove this, go ahead and freeze a bottle of water, then let it thaw completely; if there is no ice in the bottle, then the water will not come out. It only come out due to the expansion of the ice.
798005
water has an anamalous behaviour. normally substances contract on cooling but water behavs in an opposite way meaning they expand on freezing\nat a very low temperature water freezes and expands.therefore the water pipes lines burst at very low temperatures. same with glass bottles containing water kept in a freezer explodes.\nhope that helps!!!
256189
Assuming that the fluid increase is due to an increase in water, the cells will expand due to the water moving down its concentration gradient.
236269
Because the atoms in heated water are farther apart.  It actually makes the water less dense.  It then becomes easier to freeze less dense liquid.
542873
Given that water in an hypotonic environment would tend to enter the cell, causing it to swell, it would constitute an expanding force aiding cell´s growing. Think of a baloon when you blow air into it: it kindda grows.
30270
In general, a gas turns into a liquid by cooling it.
155920
Uh, the ice melts.\n\nWhen all the ice melts, you'll find that the water level of your beverage has gone down a little.  This is because water expands when frozen, which is the opposite of pretty much everything else.
251316
It expands.  \n\nHere's an interesting point... becauase it expands, the same molecules of water take up more space as a solid than as a liquid, so it's less dense.  If it contracted (like most other things do when they go from liquid to solid) it would take up less space and be more dense... so frozen water would be heavier than liquid water.  If that were the case, ice would sink, which would be a serious bummer for fish.  As it is, since water expands, solid water (ice) is lighter than liquid water, so it floats - a serious bummer for the Titanic, but a good thing for cold drinks and fishies.\n\nI love this stuff.
312206
Water continues to become more dense as it cools until just above the freezing point.  I can't remember the exact temperature off-hand, but I believe it is very near 33.5 to 34 degrees Fahrenheit.  \n\nBelow that water begins to expand and once it has frozen, its volume increases approximately 10%...that's why ice floats...less dense than the water it came from!  Cool, huh?