Science

Indecisive water can exist as two different liquids

Indecisive water can exist as ...
Researchers at Stockholm University have discovered that water exists in two liquid forms, one more viscous than the other
Researchers at Stockholm University have discovered that water exists in two liquid forms, one more viscous than the other
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Researchers at Stockholm University have discovered that water exists in two liquid forms, one more viscous than the other
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Researchers at Stockholm University have discovered that water exists in two liquid forms, one more viscous than the other

Water is way weirder than you might think. We know it can exist as a solid, liquid and gas, but put it under extreme pressure and it converts into a freaky fourth state called tunneling, and it may even freeze at temperatures it would normally boil. But now, researchers have found that water actually has two different liquid forms, and its weirdness may come from the relationship between those forms.

The finding started with the understanding that ice exists in different forms. When we freeze water at home, its molecules line up in a crystalline structure that's fairly ordered and symmetrical. But out in space, ice tends to take on a less structured, amorphous form, and even then, there are two different types with low and high densities. It's long been thought that this could apply to its liquid form, but it's never been directly observed – until now.

Using two X-ray methods to watch how the molecules move around, researchers at Stockholm University observed high-density amorphous ice as it relaxed into the low-density form. One X-ray technique gave the team a window into the atomic structure of the transition, while another let researchers study its dynamics and motion. Showing clear signs of liquid behavior, the team realized both phases were technically liquids.

"I have studied amorphous ices for a long time with the goal to determine whether they can be considered a glassy state representing a frozen liquid," says Katrin Amann-Winkel, co-author of the study. "It is a dream come true to follow in such detail how a glassy state of water transforms into a viscous liquid which almost immediately transforms to a different, even more viscous, liquid of much lower density."

The conclusion the researchers reached is that water gets its weirdness mostly from the interplay between these different liquid forms. Understanding them could help paint a wider picture of how water is affected by changes in temperature, pressure, and the addition of other chemicals.

"The new results give very strong support to a picture where water at room temperature can't decide in which of the two forms it should be, high or low density, which results in local fluctuations between the two," says Lars G.M. Pettersson, co-author of the study. "In a nutshell: Water is not a complicated liquid, but two simple liquids with a complicated relationship."

The research was published in the journal Proceedings of the National Academy of Science.

Source: Stockholm University via Science Daily

8 comments
Bob Stuart
Does this explain the vigorous circulation of small particles sometimes seen in a thin film of water on a sloped or icy surface?
IgnacioRubioLandaluce
How does this relate to the "lentils" of water found off the Gibraltar Strait? There, pockets of water with a different density and temperature than its surroundings have been found, in the shape of "giant lentils" moving about without ever mixing.
Douglas E Knapp
Bob, what you are talking about is likely brownian motion. IgnacioRubioLandaluce, this is likely water not mixing do to salinity differences. A river pouring into the sea or two types of sea water not mixing med and atlantic.
AbsolutJohn
Though this reminds me of my high school science fair project on the triple-point and beer bottles in a freezer (never underestimate the power of opening a hyper-cooled liquid bottle of beer and having it freeze instantly in your hands when you pop the cap - which is great science by the way), this actually helps provides the intrinsic science behind several natural phenomena like... - How glaciers move while frozen at sub-zero temps - Why an arctic/antarctic shelf would melt faster than we thought because of these liquid vortices - and would lead to the rapid melting of polar ice caps - Bubble spots in sandstone resulting from tunneling high-pressure jets of water
Brooke
The first thing that needs to be clarified is did they first make sure they were working with pure H20 and that there was no D2O in the mix.
Jameswa40
This sounds a little like the Super Water of 30 or 40 years ago that was very viscous and ran up hill. It eventually turned out to a concentrated solution of dissolved glass.
Bob
Water is the most amazing chemical on earth. For such a simple molecule it has a tremendous number of extraordinary properties. One way or another it is the universal solvent.
LarsPettersson
The two-liquids picture helps us understand also normal tap water. See https://www.nature.com/articles/ncomms9998 for the connection to ambient conditions