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Water Expands When It Freezes !




The molecular structure of ice is awesome.  Each molecule of water in the crystal lattice structure of ice is bonded tetrahedrally to four others through hydrogen bonding.  This is the same structure as DIAMOND in which each carbon atom is covalently bonded tetrahedrally to four other carbon atoms.  



Diamond is the hardest substance known to man. Consequently ICE is also very tough as the owners of the TITANIC discovered !

In liquid water the water  molecules (H2O) are random which is why water is fluid.  The water molecules are close together which gives liquid water a relative density of ONE. ICE has a relative density of 0.92 which is why ice floats on water. Consequently about 90% of an iceberg is under the surface of the sea another factor which was incidental in the sinking of the TITANIC.  Because ice is less dense than liquid water - water expands when it freezes as anyone will testify who has left a can of coke overnight in a freezer. This can be seen when a bottle of milk is left on the doorstep in freezing weather. The bottle has also started to crack due to the pressure. Cow's milk is 87% water. Most other liquids contract when they freeze (solidify) and become more dense.

    

One very interesting ecological outcome of water expanding when it freezes is that ponds and lakes freeze form the top downwards and not the bottom upwards.  Water has a maximum density at 4C so the water under the ice remains liquid at 4C.  Ice is bad conductor of cold so once a layer is formed the cold outside the pond cannot penetrate the ice. The ecological outcome of this is that the "pond life" stays alive and thrives under the protective covering of ice !



KOI CARP SWIMMING HAPPILY 
UNDER A layer OF ICE !




INUIT FISHING THROUGH AN ICE HOLE

DEDICATED TO ALL EP AQUAPHILES !
deleted deleted 26-30 1 Response Jun 11, 2012

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Very informative