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9

It's certainly possible for ice to sink in water under the right conditions. The diagram this section of Wikipedia's ice page will show you the conditions under which the various types of ice can form. Most of the "exotic" ones such as XII will form only at pressures greater than around 200MPa. These high-pressure forms are all denser than water, so they ...


6

The situation is well represented in the following very pictorial picture but this is a very active field of study. It is interesting to note that a real proof of existence for the critical endpoint (CEP, indicated as a critical point in the figure), both from a theoretical and numerical point of view, does not exist yet. The reason, at least for the ...


5

From the densities of liquid nitrogen and nitrogen gas at standard pressure the volume ratio is about 1:700. For an ideal gas in a closed 1L container this would result in a pressure of 700 atm according to $$P V = n R T$$ From the phase diagram nitrogen is a gas at standard pressure and becomes supercritical at approximately 100 atm. The ideal gas law can ...


5

I am curious to know under what conditions of the air pressure(atm), temperature, solute density in the water would cause the Niagara fall frozen? In general, the answer is "a bit lower than 32 Fahrenheit". Here's two things which one might think would come into play, but actually do not to an appreciable extend. Solute concentation The major ...


5

(1) Classifying "Phase Structure of (Quantum) Gauge Theory" (with a gap) is roughly the same as classifying phase structure of topologically ordered states. Some topologically ordered states are described by a group and can be related to a gauge theory. Some other topologically ordered states are not related to gauge theory. (2) One way to classify "Phase ...


3

Consider that the liquid was saturated, for a density of ~808 kg/m^3. Conservation of mass requires the density of the vapor to be the same. Using NIST's property tables you can find the pressure to be about 43,000 psi or 2,900 atm. Never do this... Both 700 atm and 82 atm are very low... NIST Data Table: http://1.usa.gov/12fCuhv


3

yes, hydrogen (and anything) evaporates/sublimes in vacuum


3

I'll make an attempt of partial answer here, and perhaps extend the question a bit : I think liquid water-gas water are already phases that spontaneously break symmetry of say your "water Hamiltonian". Since you can go continuously (without any phase transition) from one phase to the other phase (by going around the critical point at high temperature and ...


3

You are right, these terms are related. Metastability usually comes about in systems which are described by a Landau free energy which contains a cubic or power 6 term on top of the usual $\phi^4$-theory. E.g. the Landau free energy with a cubic term is shown below. There are three special temperatures: $T^{**}$ at which an additional local minimum forms ...


2

If the ice floats (and not falls to the bottom), then it is completely irrelevant what density it has. It displaces exactly the volume of the water that corresponds to its mass, and since ice melts into the water it will not change the level. Let me just supplement you that the reported density of ice XII 1.29 g/cm$^3$ is for the temperature of 127 K, I ...


2

consider the conditions of nearly completely frozen falls: which means there are water branches from the very top of the falls are frozen connected to the bottom of the falls. The picture you shown suggests the stuffs connecting from top of waterfall to the bottom is icicle, which can only be formed with not so fast flowing of water, otherwise high ...


2

We normally consider the various states of matter to be separated by a phase transition, and generally this is a first order phase transition (an exception is the second order glass-liqid transition). So for example the solid to liquid transition is (usually) a first order phase transition, and likewise the liquid to gas transition. However if we move from ...


2

The way to distinguish intermetallics (or any other phases) is to used the commonly accepted phase description, such as Mg$_{2}$Pb as you did above. This phase descriptor than points people to information on the crystal structure, thermodynamics of the phase, etc. The point is that these are thermodynamically distinct phases - a first order phase transition ...


1

No. As @Jim said, the heat would weaken the rock, which would cause a tunnel collapse before any sublimation could occur. Also, remember that the air in the tunnel would generally be at the same temperature as the rock (unless a large cooling system was put in), so thermal equilibrium would be maintained without any sublimation.


1

In principle, it is very simple and straightforward. The problem is to map out the region where the integer filling state is the ground state. Suppose you have $L$ sites. Take $N=L$ particles, find its ground state energy, which is denoted as $E_g(L)$. Note that here the Hamiltonian does not contain the $\mu $ term. Do it again for $N=L+1$, the ground ...


1

Introduction In this answer, I first tackle the simpler problem of a mixture with three types of molecules identical in size. This has relevance to the original question in that the third component does not directly interact with the others, yet its introduction changes the phase diagram through entropic effects. Small molecules Take the Flory-Huggins ...


1

By definition, as long as you are only talking about floating ice, the water level must stay the same when the ice melts - it is already displacing it's mass of water, whether it is solid or liquid. (For land based ice, please have a look at my answer to this question over on Skeptics)


1

(Assuming that you don't heat enough to change the density of the pre-existing liquid water) Any floating body displaces as much liquid as its weight. So, let's say we have 5g of ice. Part of it will be above water. The part that is below the water level will have a net volume equal to the volume of 5g of liquid water. So, if the ice melts, it will become ...


1

The theoretical equation you are looking for is actually referred to as a model, which you must hypothesise based on sound reason. The exponential model is one that allows for a rate of change proportional to the current value--for experiments such as objects being decelerated by air resistance (air resistance depends on how fast the object is moving), or ...



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