🚀 go-pugleaf

tom@stl.stc.co.uk (Tom Thomson) writes:
>In article <29046@boulder.Colorado.EDU> eddy@boulder.Colorado.EDU (Sean Eddy) writes:
>>Osmosis is a colligative property. That is, osmotic pressure is
>>dependent on the *number* of particles in solution -- *not*
>>their size, mass, etc. 
>The interesting thing is how much space they take up, not how big
>they are:  it's not as if they were closely and rigidly packed so
>that the space they take depends on their size.   Even with BIG
>molecules in solution, the average radius is SMALL compared with
>the mean free path.

What you say is generally true of a gas.  A liquid is not a gas.

In a solid you will probably agree that the molecules are more or less
"closely and rigidly packed."  Since liquid water is more dense than
ice, we can conclude that water molecules are pretty closely packed as
a liquid.  The space occupied by small molecules and radicals in solution
cannot be anywhere near the space occupied by a DNA molecule.

density of water == 1 g/cc == 1/18 mole/cc == 1/3 * 1e24 molecules/cc
Since 1 cc == 1e24 cubic Angstroms,
density of water == 1 molecule / 3 cubic Angstroms.

Richard M. Mathews			D efend
Locus Computing Corporation		 E stonian-Latvian-Lithuanian
richard@locus.com			  I ndependence
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