Water; has unusual not explained features (Introduction)

by David Turell , Sunday, July 19, 2020, 00:36 (1591 days ago) @ David Turell

Another study:

https://www.sciencedaily.com/releases/2020/07/200716144719.htm

"A new study provides strong evidence for a controversial theory that at very cold temperatures water can exist in two distinct liquid forms, one being less dense and more structured than the other. Researchers conducted computer simulations of water molecules to discover the critical point at the transition between the two forms.

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"Now a new study provides strong evidence for a controversial theory that at very cold temperatures water can exist in two distinct liquid forms, one being less dense and more structured than the other.

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"Water's oddities include that as water cools, it expands rather than contracting, which is why frozen water is less dense than liquid water. Water also becomes more squeezable -- or compressible -- at lower temperatures. There are also at least 17 ways in which its molecules can arrange when frozen.

"A critical point is a unique value of temperature and pressure at which two phases of matter become indistinguishable, and it occurs just prior to matter transforming from one phase into the other.

"Water's oddities are easily explained by the presence of a critical point, Debenedetti said. The presence of a critical point is felt on the properties of the substance quite far away from the critical point itself. At the critical point, the compressibility and other thermodynamic measures of how the molecules behave, such as the heat capacity, are infinite.

"Using two different computational methods and two highly realistic computer models of water, the team identified the liquid-liquid critical point as lying in a range of about 190 to 170 degrees Kelvin (about -117 degrees to -153 degrees Fahrenheit) at about 2,000 times the atmospheric pressure at sea level.

"The detection of the critical point is a satisfying step for researchers involved in the decades-old quest to determine the underlying physical explanation for water's unusual properties.

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"'You can imagine the joy when we started to see the critical fluctuations exactly behaving the way they were supposed to," Sciortino said. "Now I can sleep well, because after 25 years, my original idea has been confirmed."

"In the case of the two liquid forms of water, the two phases coexist in uneasy equilibrium at temperatures below freezing and at sufficiently high pressures. As the temperature dips, the two liquid phases engage in a tug of war until one wins out and the entire liquid becomes low- density.

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"Some of the odd behaviors of water are likely to be behind water's life-giving properties, Zerze said. "The fluid of life is water, but we still don't know exactly why water is not replaceable by another liquid. We think the reason has to do with the abnormal behavior of water. Other liquids don't show those behaviors, so this must be linked to water as the liquid of life."

"The two phases of water occur because the water molecule's shape can lead to two ways of packing together. In the lower density liquid, four molecules cluster around a central fifth molecule in a geometric shape called a tetrahedron. In the higher density liquid, a sixth molecule squeezes in, which has the effect of increasing the local density.

"The team detected the critical point in two different computer models of water. For each model, the researchers subjected the water molecules to two different computational approaches to looking for the critical point. Both approaches yielded the finding of a critical point."

Comment: A very strange liquid but extremely vital for life to exist. Must be purposeful.