I see a market opportunity. Think about the ad campaign for *pure* ortho water. You *do* want all of your water be straight, don't you! On Sep 21, 2005, at 1:53 PM, Eugene Salamin wrote:
I found a great web site on water: http://www.lsbu.ac.uk/water/ . There is so much good stuff here; I'll just mention a few tidbits.
According to data from this source
Density of H2O ice = 0.9168 Density of D2O ice = 1.0175
So we might expect HDO ice to have density 0.967, i.e. floats.
Note that HDO does not exist as a pure substance; it is a mixture of H2O, HDO, and D2O molecules. Furthermore, in equilibrium at 25 C,
H2O + D2O <==> 2 HDO, Keq = 3.85,
not the value 4 one would expect from total randomization. This is attributed to D2O having stronger hydrogen bonds than H2O.
In addition to the isotopic molecular species due to H, D, and the radioactive T, and also the stable O-16, O-17, and O-18, there is another class of distinct molecules that differ in the alignment of their nuclear spins. Considering only H2O, the H nuclei (protons) have spin 1/2. In ortho-water, the two spins are parallel, resulting in total nuclear spin 1, while in para-water, the spins are antiparallel, resulting in total nuclear spin 0. The equilibrium ratio is all para at 0 K, and 3:1 ortho:para at high temperatures (> 50 K). The equilibration time is about 1 hour in liquid water and several months in ice. It appears possible to separate ortho and para-water, but I can't say more because I don't have access to the journal articles from here.
Similar considerations apply to the hydrogen molecule H2. When hydrogen gas is liquified, it retains the 3:1 ratio. As ortho-hydrogen slowly converts to para-hydrogen at cryogenic temperatures, the energy released causes a substantial evaporization of the liquid. For this reason, a catalyst is used to quickly convert the hydrogen to para form. This can double the storage lifetime of the liquid.
Occurring in conjunction with ordinary water is the extremely dangerous chemical dihydrogen monoxide (DHMO). Learn about it at http://www.dhmo.org/ .
Gene
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