New evidence shows water separates into two different liquids at low temperatures

[sl8]

https://www.birmingham.ac.uk/news/2022/new-evidence-shows-water-separates-into-two-different-liquids-at-low-temperatures

New evidence shows water separates into two different liquids at low temperatures

Fresh evidence that water can change from one form of liquid into another, denser liquid, has been uncovered by researchers.

Published 18 August 2022•5.5 min read

The research was carried out at the University of Birmingham and Sapienza Università di Roma.

A new kind of ‘phase transition’ in water was first proposed 30 years ago in a study by researchers from Boston University. Because the transition has been predicted to occur at supercooled conditions, however, confirming its existence has been a challenge. That’s because at these low temperatures, water really does not want to be a liquid, instead it wants to rapidly become ice. Because of its hidden status, much is still unknown about this liquid-liquid phase transition, unlike about everyday examples of phase transitions in water between a solid or vapour phase and a liquid phase.

This new evidence, published in Nature Physics, represents a significant step forward in confirming the idea of a liquid-liquid phase transition first proposed in 1992. Francesco Sciortino, now a professor at Sapienza Università di Roma, was a member of the original research team at Boston University and is also a co-author of this paper.

The team has used computer simulations to help explain what features distinguish the two liquids at the microscopic level. They found that the water molecules in the high-density liquid form arrangements that are considered to be “topologically complex”, such as a trefoil knot (think of the molecules arranged in such a way that they resemble a pretzel) or a Hopf link (think of two links in a steel chain). The molecules in the high-density liquid are thus said to be entangled.

In contrast, the molecules in the low-density liquid mostly form simple rings, and hence the molecules in the low-density liquid are unentangled.

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[Bernardo de La Paz]

1. Good thing it is not Ice-9. . . .nt

[Hekate]

3. Indeed not

[ProfessorGAC]

8. Speaking Of Which...

...this is in my top 5 songs by Satch.

[Aussie105]

2. Not surprising.

Most polar molecules (like water) will form into repeated patterns under the right conditions.
The molecules will fit together better under a low energy state, and be more dense.
It would need to be very pure water, with no other molecules present to form a nucleus for ice formation.

Interesting research for the sake of research.

Think of carbon - soot, basically - forming into a regular structure we call a diamond under the right temperature and pressure conditions.

[Backseat Driver]

7. Is shungite, (2 varieties) which is classified as a mineraloid, though carbon-based and said to have

fullerene structures within also on its way at some point to differentiated carbon states of alignment: crystal diamond and graphite, solid varieties of coal useful for combustion burning/graphenes having a single-layer honeycomb structure, or fluid-flowing liquid oil?

I was given to understand these shungite rock varieties are not commonly found, its largest mined deposit being found in Karelia, Russia. Could its existence/formation be related to this mid-point change in water?

Shungite seems to have a lot folk mythologies of properties allowing it to filter water. removing impurities, and also said to deliver other healthy dissolved minerals by absorption including guarding the human body by absorbing and collecting radiation/electro-magnetic waves that sail through our environment. Really doesn't seem that chemists or material engineers have much interest in any other science-based uses...Could this transitional state of water have any bearing on this mythologized rocky mineraloid?

[BumRushDaShow]

4. Water has always had such unique properties

like expanding vs contracting when in the solid phase and more easily reaching a condition of a "triple point" (with all 3 phases existing at the same time), so this seems to make sense as an "observed" transition within one of the states.

[Joinfortmill]

5. Fascinating

[reACTIONary]

6. Very interesting theoretical work...

... but no empirical confirmation as of yet. Maybe their colloidal model will help provide experimental evidence.