Why does water have maximum density at 4°C?

[Borek]

Steve, I guess the real question here is at what pressure we will stop calling substance a water. We know matter can be squeezed to the limits seen in neutron stars, which is around 10¹⁷ kg/m³. Somewhere between 10³ kg/m³ and 10¹⁷ kg/m³ chemical substance stops to be a chemical substance.

 

[steve.mileman]

On at least one level about changes of state in water



Maxim Vengerov, the violinist said that he remembered that as a child in Siberia where he lived and learned to play the violin, the warmest place in the house was in the fridge where it was only 4 deg C. Outside it was -40.

 

[steve.mileman]

Glass is certainly not a liquid at room temperature.

There I beg to differ. It may flow very slowly but a liquid flows and that is what glass does. There are many examples in old window panes that are thicker at than at the bottom. But its easy to prove.

 

[Borek]

There I beg to differ. It may flow very slowly but a liquid flows and that is what glass does. There are many examples in old window panes that are thicker at than at the bottom. But its easy to prove.

Unless it is just an urban legend...

 

[Hootenanny]

There I beg to differ. It may flow very slowly but a liquid flows and that is what glass does. There are many examples in old window panes that are thicker at than at the bottom. But its easy to prove.

You can beg all you like, but as Borek says,

Unless it is just an urban legend...

it is just an urban legend.

Glass is an amorphous solid, which contrary to popular belief, does not flow to any appreciable extent. The thicker bottomed windows pains are a result of the pre-float line manufacturing processes.

 

[steve.mileman]

Steve, I guess the real question here is at what pressure we will stop calling substance a water.

Borek, thank you. I believe you are right that we ought to define the question more accurately if we can.

Reading Teboul's article (referred to above in one of my posts,) the problem is that in both bulk and hydrophilic nanopore simulations there were differences as a result of heterogeneity within the samples themselves.

We are really looking at the variety of states in which two hydrogen atoms and one oxygen can exist. We know that in one state we can simply call it “water” because we can see it and drink it and we don’t necessarily have to worry about how it behaves at a molecular level. Yet we know that in membranes (at the least for us as living organisms) we are fortunate the water is capable of it’s peculiar behave.

Down the tumultuous scale to rock bottom, these atoms are not as happy to share a confined space as Teboul says correlates with work on confined Lennard-Jones liquids.

My question is less about the relationship than about the divorce.

 

[steve.mileman]

You can beg all you like,

My apologies Hootenanny. I was too hasty. I want to focus on water, but since you raise it and I now I have to be suspicious at best about the ancient window pane through which I have seen my own distortion, let me say that there appear to be different views. Check out : http://www.xs4all.nl/~johanw/PhysFAQ/General/Glass/glass.html

“It would be convenient if we could conclude that glassy materials changed from being a supercooled liquid to an amorphous solid at the glass transition, but this is very difficult to justify. Polymerised materials such as rubber show a clear glass transition at low temperatures but are normally considered to be solid in both the glass and rubber conditions.
It is sometimes said that glass is therefore neither a liquid nor a solid. It has a distinctly different structure with properties of both liquids and solids. Not everyone agrees with this terminology.”

But I have to concede that it is not a simple question of being a liquid.

 

[Hootenanny]

My apologies Hootenanny. I was too hasty. I want to focus on water, but since you raise it and I now I have to be suspicious at best about the ancient window pane through which I have seen my own distortion, let me say that there appear to be different views. Check out : http://www.xs4all.nl/~johanw/PhysFAQ/General/Glass/glass.html

“It would be convenient if we could conclude that glassy materials changed from being a supercooled liquid to an amorphous solid at the glass transition, but this is very difficult to justify. Polymerised materials such as rubber show a clear glass transition at low temperatures but are normally considered to be solid in both the glass and rubber conditions.
It is sometimes said that glass is therefore neither a liquid nor a solid. It has a distinctly different structure with properties of both liquids and solids. Not everyone agrees with this terminology.”

But I have to concede that it is not a simple question of being a liquid.

I am more than happy to concede that there are different interpretations of the state of glass. Moreover, I am happy to have an in-depth debate on the merits of classifying glass, and other materials in general, into strict categories. I was merely, objecting to the assertion that glass is a super-cooled liquid, without any qualification.

 

[steve.mileman]

I was merely, objecting to the assertion that glass is a super-cooled liquid, without any qualification.

The question could be up for debate but I am inclined to agree having looked at the Scientific American article. A few things stand out though: I would have thought that to behave as a liquid it would have to flow within a fairly short space of time. The difficult of molecules being able to pass one another easily probably makes it behave observably like a solid rather than a liquid. I like the Scientific American quote for the moment.


"Glass, however, is actually neither a liquid—supercooled or otherwise—nor a solid. It is an amorphous solid—a state somewhere between those two states of matter. And yet glass's liquidlike properties are not enough to explain the thicker-bottomed windows, because glass atoms move too slowly for changes to be visible."

 

[Studiot]

For your information, Steve, even solids flow, albeit not as readily as fluids.

But what, exactly, is now your point or question?

 

[Danger]

Thank you, both Hoot and Borek.
Steve, can you please, just for the sake of this thread, disregard the fact that I'm an alcoholic? Even when I'm as pissed as a nit, I do try to maintain a scientific approach to things. I am not the one who instigated a reference to whiskey in this thread. (And by the bye, the suggestion that I would drink JD bourbon is very insulting. That's a poor substitute for real whisky.)

 

[steve.mileman]

QUOTE=Studiot;3028493]For your information, Steve, even solids flow, albeit not as readily as fluids.



But what, exactly, is now your point or question?[/QUOTE]



Yes Studiot, but we are way off my question answering anything but:



Three posts that may resurrect the question:



Steve:



We are really looking at the variety of states in which two hydrogen atoms and one oxygen can exist. We know that in one state we can simply call it “water” because we can see it and drink it and we don’t necessarily have to worry about how it behaves at a molecular level. Yet we know that in membranes (at the least for us as living organisms) we are fortunate the water is capable of it’s peculiar behave.



Down the tumultuous scale to rock bottom, these atoms are not as happy to share a confined space as Teboul says correlates with work on confined Lennard-Jones liquids.



My question is less about the relationship than about the divorce.



The second Last Post.



Borak says:

Steve, I guess the real question here is at what pressure we will stop calling substance a water. We know matter can be squeezed to the limits seen in neutron stars, which is around 1017 kg/m3. Somewhere between 103 kg/m3 and 1017 kg/m3 chemical substance stops to be a chemical substance.



The Last Post: A return to the question under debate in relation to water:



Steve Quoted



"It is evident that most anomalous behavior must involve a quite sudden discontinuity at about the homogeneous nucleation temperature (~228 K, where the densities of supercooled water and ice approach) as the tetrahedrally arranged hydrogen bonding approaches its limit (two acceptor and two donor hydrogen bonds per water molecule) and no further density reduction is possible without an energetically unfavorable stretching (or breaking) of the bonds"

"Supercooled and cold (< 3.984°C) liquid water both contract on heating [68]. As the temperature decreases, the cluster equilibrium shifts towards the expanded, more open, structure (for example, ES), which more than compensates for any decrease in volume due to the reduction in the kinetic energy of the molecules."



Steve now says:

And then what? Let's take the last statement to its next level. My gut is saying that the distortion of atomic bonds referred to Teboul, (I think) should cause some interesting new characteristic to arise. For the sake of the debate, let's still call this water in deference to Borek’s point on the definition of water.

 

[steve.mileman]

Thank you, both Hoot and Borek.
Steve, can you please, just for the sake of this thread, disregard the fact that I'm an alcoholic?

Danger,

Never fear! I hope I sussed you out at the beginning. I don't believe a word of what you say about your own "state" other than I suspect that you watch with a keen and interested scientific eye, while lightning the mood with some banter. I really enjoy it and I am waiting for the invertible spot-on observation from you.

As the the JD I have to say that I think perceptions of both quality and state are relative. I bet that exposed to more JD you would abandon all competing views. If you say "no" then I would be interested to know why you think those views may not change.

Thanks for being there.

 

[steve.mileman]

Steve, even solids flow.

The difference between solid and liquid states is not clearly defined. I think we have to leave the "glass" discussion which was a mistake for me to introduce.

But let's bear in mind that we are looking beyond the distinction between solid and liquid. We are looking into a state where I suspect that we will find several intermediate states that have different characteristics within different time frames. I hope will capture the interest of someone who can look at the change of state as it approaches a break or bending in the forces. Those conditions in which hydrogen and oxygen can no longer bond. We have prescribed that they cannot escape (immediately and hypothetically) so we can look at how they attempt to escape and under what conditions. How those bonds are stretched until they break?

It’s like the several different states of ice water. Let’s not call all states of ice just "ice" so to speak. That prevents us from asking how each state distinguishes itself from the other. I expect we will several states of solid and transitions between those states.

 

[steve.mileman]

So there are no more takers ... ?

Well here is David Peat's view in “Superstrings”:

"Below the Planck length, we would not expect to see many of the usually space-time properties; there would be no sense of length, no measure or metric to the space."

“…at around Planck length, something like a phase transition occurs. [A phase transition takes please when ice changes into liquid water or water into steam. While a dramatic change occurs at 0 degrees C or 100 degrees C, the “essence “ of water in its molecular form does not, however, change, so that “water” could be said to exist in several phases or forms.}

“Above Planck length distance has a meaning: below the Planck length physicists would have to reply on topological properties”

Peat gives “carbon” as another example of the many phases in which this element can exist. The phase is which it breaks down is where relativity and quantum states are difficult to describe (or imagine) in 4 dimensions.

One theory of the phase change below Planck length is that the molecular structures break down into superstrings that are best described in more than 4 dimensions and probably work best in 10 dimensions. In any event I would expect that strange things begin to occur in water as it approaches a very dense state. I wonder if the same thing happens to all molecules as they breakdown. Perhaps there is a similar window period between very dense and breaking apart.

Is there anyone who has an up-to-date view on this?

 

[alxm]

Peat gives “carbon” as another example of the many phases in which this element can exist. The phase is which it breaks down is where relativity and quantum states are difficult to describe (or imagine) in 4 dimensions.

That sounds like a load of nonsense. It seems to me Peat made an analogy to phase changes to describe symmetry breaking. That does not mean he's talking about chemical phase transitions, which have nothing to do with string theory at all, and are completely understood in our current understanding of quantum mechanics*.

Superstrings, if they exist, and the Planck length are farther removed from the atomic scale than the atomic scale is from the everyday scale. It's like claiming the motion of billiard balls is quantum-mechanical.

* Which does not mean there aren't things we don't know about phase changes. In fact, there's plenty we don't know about phase changes. But the fundamental interactions involved in them are completely known, and hardly require General Relativity to explain.