Steve
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Registered: 30th Mar 02
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went to the fridge this morning and got the lemonade out, new bottle unopened.
When i got it out it had frozen, undid the top and the ice was bursting to get out, spilling over the top etc!
In science i was always taught that when sumthing changes state to go fro liquid to solid the molecules slow down etc and group together tighter to form a solid, so if the molecules are coming together closer how come the general mass expands 
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Cybermonkey
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steven, when water freezes in a bottle, it actually expands, not contracts. Only water based liquids do this. Water actually uses the least space for same mass in liquid state rather than as a solid or gas.
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Red_SXi
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8/10 from the nigerian judge
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Steve
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Registered: 30th Mar 02
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quote:
Originally posted by Cybermonkey24
steven, when water freezes in a bottle, it actually expands, not contracts. Only water based liquids do this. Water actually uses the least space for same mass in liquid state rather than as a solid or gas.
so water is the exception to the rule then?? to becomne a solid though the molecules MUST come closer together else it wouldnt be a solid, i dont understand if they are coming closer together surely that would mean it would condense
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Cybermonkey
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yes water is the anomoly to the rule. It is the way the bonds between water molecules form. It is an unusual process that results in overall expansion
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Gavin
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 waaayyy too early on a sunday (esp when ur still pissed from the previous nite) to be reading this post
pew pew pew pewwwww
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SetH
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ditto
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vibrio
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quote:
Originally posted by Steve
went to the fridge this morning and got the lemonade out, new bottle unopened.
When i got it out it had frozen, undid the top and the ice was bursting to get out, spilling over the top etc!
In science i was always taught that when sumthing changes state to go fro liquid to solid the molecules slow down etc and group together tighter to form a solid, so if the molecules are coming together closer how come the general mass expands
Water is peculiar. When most substances change from liquid to solid form, they shrink together, become denser, their molecules packed most closely together.
But when water changes from a sloshy liquid to solid ice, it expands, becomes less dense. Which is why ice floats to the top of your Coke, rather than sinking like a stone to the bottom.
At normal atmospheric pressure, molecules usually behave in predictable ways as their temperature changes. Molecules fly apart into a gas when heated, condense into a flowing liquid when cooled, and shrink into a frozen solid when chilled still further. The changes in state parallel changes in energy: from high energy to medium energy to barely jiggling.
Boiling water expands into a gas (steam) and wafts off into the kitchen. But we also see water expand when chilled in the freezer. An ice cube tray filled to the rim the night before overflows with big cubes of ice in the morning.
Water starts out behaving normally. As its temperature drops, water obediently shrinks together--until it reaches 4 degrees Celsius (39 degrees F.). Then, amazingly, water reverses course, its volume slowly increasing as it chills. When water finally freezes, at 0 C (32 F.), it expands dramatically.
Scientists say water's quirky behavior is caused by the shape of its molecule and by how its molecules bond to one another.
Each water molecule is two hydrogen atoms bonded to one oxygen atom (H2O). Because of how the atoms share electrons, a water molecule is slightly positively charged at the hydrogen atoms, and slightly negatively charged at the oxygen atom. The molecule's charged ends attract the oppositely charged ends of other water molecules ("hydrogen bonding").
In liquid water, as molecules slip-slide past each other, bonds form, break, and re-form. But by the time water has cooled to 4 C., the molecules' energy has dropped enough that they are very near one another. So each H2O molecule forms more stable hydrogen bonds, with up to four fellow molecules.
By 0 C. (32 F.), the H2O molecules are snappily lined up in a frozen crystal lattice, an open hexagonal (six-sided) shape. Unlike in liquid water, the molecules in ice are held rigidly apart. That means more empty space between molecules, so frozen water occupies more room.
Result: Put 10 cups of water in the freezer, take out nearly 11 cups of ice!
Other real-world results: Water pipes freeze and burst in unheated houses. Water collects in roadway cracks in winter, turns to ice, and enlarges crevices into gaping potholes.
If frozen water weren't less dense than liquid, there would be no floating icebergs to sight off the bow of a ship. There would be no skating on ice-covered ponds, while fish and other life shelter in insulated water below. If water froze from the bottom up, much of Earth's water would solidify in winter, and life might be impossible.
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Cybermonkey
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Ctrl-C
Ctrl-V
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vibrio
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yes - although it did al come back to me when I read it. ah thermodynamics
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Cybermonkey
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yes, i can see myself now sitting in Physics next to a girl with big breasts. I am quite suprised i remember anything considering this.
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