Why is H2O the only liquid that expands when frozen?
440171
Because of hydrogen bonding, it forms a hexgonal ring, and this creates space in the middle of the rings.  This space accounts for why water expands when in it's frozen state.
101455
>>>>>at 4 degrees above its freezing point, water sinks.\n\nThis is true.\n\n>>>>any lower, and it begins to freeze, forms crystals, and floats.\n\nThis is not true. Water begins to freeze at 0oC, not at 3.9oC or even 1oC.\n\n>>>>any warmer, and the molucular action makes it less >>>>dense.\n\nThis is not true. Water becomes less dense at warmer temperatures due to kinetic motion impeding the formation of hydrogen BETWEEN molecules.
475191
it's my understanding that it doesn't really 'explode' - when liquids freeze they generally expand and become hard. since the coke is contained by a can, with part of the top thinner around the tab (due to the scoring), when the liquid starts freezing in some part of the can the remaining liquid is displaced so there is part ice and part liquid. Finally, the remaining liquid freezes, and because there is less room in the can (due to the previous frozen matter, which has taken up more room)there is not sufficient room for all the  material which is trying to freeze - and the can separates at its weakest points. That's why when you open the freezer you may find some contents which have burst out and refrozen once they have'escaped' confinement.
858544
Because water expands when it freezes..\nTherefore ice is of larger volume than the water it originated from\ntherefore it is less dense..
1142625
You are thinking of two different states of matter. If you liquify hydrogen and oxygen they are visable. Likewise, you cannot see a single molecule of water in the gaeous state. Now lets talk about steam and clouds both are water vapor and are visable. The water molecules are approaching the freezing point which is much higher than H or O. As the temp drops the H2O molecules lack the energy nescessary to overcome the forces which cause them to cling together. They are forming droplets. H and O would do this also if you started bring them close to there freezing point.
782187
When salt (NaCl) is absorbed into water (H2O) A new molecule is formed (NaH2ClO). When this new molecule is frozen, the crystalline structure is much stronger than that of regular water. This is why icebergs sink ships and ice cubes can be crushed by your refrigerator.
82013
The question about water expanding is not really broad enough to merit an entire project, much less an experimentation.\nThe reason why water expands when frozed can be easily researched and I cannot think of how you would try to turn this into a science project using the scientific method with an experiment.\n\nThe project involving gold balls however does have a clear problem and variables you could control.\nIf your forced to choose either of the two, the better project in my opinion is the golf ball project.
161280
Same reason a water bottle will crack(water expands when frozen), the only difference is the carbonated drinks aren't completely frozen so it leaks everywhere.
1010626
Could be that different chemical compounds freeze at different temperatures.  Water freezes at a lower temperature than 36 degrees but not everything does.  That is also like why you put salt on ice to thaw it, it lowers the freezing point, so it has to be a lot colder before you get ice.
706444
Density= Mass/Volume.  When water freezes, its volume increases. This is why a frozen bottle of water expands to the point of bursting. By the formula, if volume increases and Mass stays the same, then the value of density decreases.  Thus, this is why ice floats and is less dense than water.  When the ice melts, the reverse happens in that its volume decreases and again by the formula, density will increase.   Tahdaaaa!!
1078588
yes the glass would break because unlike any other liquid water expands when frozen therefore the glass would break regardless of how full it is
273941
to take grandeyeglass's link one level further,\nhttp://www.lsbu.ac.uk/water/phase.html\nWould be nice to get this chart overlayed with adiabatic and iso-volumetric contours.\n\nSo the answer is YES there are pressure/temp regions where the only difference between liquid and solid is purely pressure.\n\nAt a temperature of -10C, and a pressure of 200MPa, H2O is liquid. But if you increase the pressure to 450MPa, H2O solidifies to ice-V with a density of 1.23 g/cc. Also, amazingly, if you decrease the pressure from 200 to 100MPa, it solidifies to ice-Ih with a density of 0.92 g/cc.\n\nAt room temp (20C) you have to increase the pressure to 900MPa to solidify it to ice-VI with a density of 1.31 g/cc.\n\nH2O is amazing stuff... I have learnt something here...
895765
Temperature must get below 32 degrees Fahrenheit or 0 degrees Celsius.\n\nWhen it gets that cold, the H2O particles have more resistance moving around until they move around less and less until water freezes. The particles are still moving... just very slowly. The particles also get larger in this process; thus the reason why ice expands.
314279
The reason that water expands upon freezing is because of the strong hydrogen bonding between the water molecules. Water is polar having a positive end nearest the Hydrogens and a negative end nearest the Oxygen atom. Therefore The positive ends of some water molecules attract the negative ends of other water molecules. When water reaches 4 degrees Celsius the molecules have been pushed as close to one another as they will be. Below 4 degrees the water molecules begin to align themselves into the crystal structure of ice. This requires the water molecules to widen the angle between the Oxygen Hydrogen single bonds . When this happens the water molecules take up more space hence expansion.
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.
1047534
Ice expands during the freezing process by blending with air.. but when frozen it is one of the very few things that goes through a process called sublimination .. straight to vapor form from solid without being a liquid in between.. this is why ice cubes shrink over time when left in the freezer for long periods.. pretty cool stuff \n.. damn, I actually remembered something from high school .. haaa
313475
The primary reason water expands upon freezing is the breakage of hydrogen bonds.  The hydrogen bonding which occurs in the polar water molecules acts to bind water molecules closer together than they would otherwise.  When freezing, though, those hydrogen bonds must break in favor of the crystalline solid structure (which packs the molecules less densely).  Hydrogen bonding also leads to the extremely high boiling point of water for such a small molecule (most molecules of small molecular weight are gases at much lower temperatures than 100 deg C).\n\nIn fact, hydrogen bonding contributes to just about every unusual property of water.  There are very few molecules in nature that exhibit hydrogen bonding; and none, to my knowledge, exhibit it as strongly as water.  Alcohols have some hydrogen bonding, which is why they have higher boiling points than other, comparable molecular weight organics.