6 ms·
ELI5 please?
by rosstex 10y ago
ELI5 please?
- chadcmulligan 10y agothe conclusion probably says it all? "In conclusion, a review of the physical properties of water in the 0–100°C temperature range reveals a bilinear behaviour that defines a crossover temperature at 50 ± 10°C. This observation supports the hypothesis that there are two states of liquid water. We find that these two states play an important role in the thermal and optical properties of nanomedical systems. Finally, our preliminary findings suggest that the structure of liquid water strongly influences the thermal stability of proteins. More in-depth research on the thermal stability of proteins dispersed in liquid water is needed."
- simooooo 10y agoIs this why hot water from a tap sounds notably different from cold?
- CamperBob2 10y agoMost likely that's due to different amounts of dissolved air in the water.
- pizza 10y agoIt has to do with the size of the produced air bubbles and the mechanics of/lengths of the columns of falling water. But that said, this could play a bit of a role in those reasons.
- carlob 10y agoI don't think most taps reach 60° C. That would be 140° F in freedom units…
- mirimir 10y agoYes, but just what are those states? I see no explicit hypotheses. The clearest hint that I see is that the calculated dipole moment is 2.3 Ds at 0–60°C, "which is close to the value for ice", and 1.8 Ds at 60–100°C, "which is comparable to that reported for the vapour phase". Lower dipole moment means weaker hydrogen bonding, and less tetrahedral structure.
- chadcmulligan 10y agooh ok, I don't think they know yet - still some research to be done, the states have just been identified
- the8472 10y ago> Yes, but just what are those states? That's covered in the introduction. > Despite these efforts, the structure of liquid water is still not fully understood. > This suggests that there are of two states in bulk liquid water that differ in the amount of their dipole moment. Unfortunately, a correlation between the dipole moment and the microscopic structure of these two states has not yet been determined.
- mirimir 10y agoYes, I should have quoted those bits.
- zeofig 10y agoThe (purported) states are very similar. They have slightly thermal conductivities, electrical conductances etc. but still have all the usual properties of water (as they must, since we observe 60 degree and higher water all the time, and it still behaves like water).
- marcosdumay 10y ago> Lower dipole moment means weaker hydrogen bonding Wouldn't weaker hydrogen bounding imply on much lower surface tension? There is some smaller tension, but the trend is really tiny.
- mirimir 10y agoWell, all of the reported differences are small changes in temperature dependence. Water is a strange thing. But for the strong hydrogen bonding, it would be a gas at ambient temperatures. Consider methane and ammonia, for example. So I don't think that they've found a new phase of water. Rather, as the title states, they argue that liquid water is a mixture of two states, one ice-like with strong hydrogen bonding and tetrahedral structure, and the other more disordered, gas-like, with weaker hydrogen bonding. It's just that there's something like a figure/ground transition at 50-60°C. Going from islands of "gas-like" structure in a sea of "ice-like" structure, to islands of "ice-like" structure in a sea of "gas-like" structure.
- raverbashing 10y agoI wonder if this is related to https://en.wikipedia.org/wiki/Mpemba_effect https://en.wikipedia.org/wiki/Mpemba_effect
- joveian 10y agoUnlikely, see "When does hot water freeze faster then cold water? A search for the Mpemba effect" by James D. Brownridge: https://arxiv.org/abs/1003.3185 https://arxiv.org/abs/1003.3185