Questions tagged [phase-diagram]
243 questions
98
votes
3 answers
First and second order phase transitions
Recently I've been puzzling over the definitions of first and second order phase transitions. The Wikipedia article starts by explaining that Ehrenfest's original definition was that a first-order transition exhibits a discontinuity in the first…
N. Virgo
- 35,274
69
votes
2 answers
Why was water freezing almost instantaneously when shaking a bottle that spent the night outside during a frosty night?
Due to the forecasted frost last night, I placed yesterday evening, some 1.5l standard PET bottles filled up to 90% with warm tap water(+60°C) close to some vegetables that I wanted to protect in my garden. The temperature dropped to roughly -3 ~…
s.k
- 799
46
votes
2 answers
What happens when you put water under intense pressure?
Pretend you have an indestructible tube that cannot leak, inside which is water. Imagine that in each side of the tube, you have very powerful pistons
What would happen if you compress the water inside?
Would it turn into heat and escape the…
Kiran Kharel
- 515
32
votes
5 answers
Why does a critical point exist?
I still cannot fully comprehend the essence of a critical point on phase diagrams.
It is usually said in textbooks that the difference between liquid and gaseous state of a substance is quantitative rather than qualitative. While it is easy to…
xaxa
- 1,672
23
votes
1 answer
Phase Structure of (Quantum) Gauge Theory
Question: How to classify/characterize the phase structure of (quantum) gauge theory?
Gauge Theory (say with a gauge group $G_g$) is a powerful quantum field theoretic(QFT) tool to describe many-body quantum nature (because QFT naturally serves…
wonderich
- 8,086
19
votes
2 answers
Phase transition water
The water-gas phase transition is said to be similar to the ferromagnetic-paramagnetic phase transition (same set of critical exponents = same universality class). In the former case the order parameter is the difference in the densities, while in…
nervxxx
- 4,520
14
votes
3 answers
How to freeze the Niagara waterfalls?
Here is a picture of the usual vigorous Niagara Falls (in the winter).
Here is the picture of Niagara Falls frozen in 1933 (in the very cold winter).
Here is the picture of Niagara Falls frozen in 1911 (in the extremely cold winter).
Background…
wonderich
- 8,086
14
votes
2 answers
What leads to the existence of critical temperature?
We know that $T_c$ is the temperature above which no amount of pressure could force a gas to liquefy.
But why is this? Somehow I don't buy the point that the gas molecules exert too much pressure back to get close and turn into a liquid. If we had…
cst1992
- 305
13
votes
4 answers
Could a gas go directly to a solid without becoming a liquid?
If water vapor is pulled inwards and cooled at a fast enough rate could if be frozen back into a solid form? i understand that they would have to be froze together as soon as contact is made but if this is possible what would the temperature have to…
12
votes
3 answers
Pressure of sealed in liquid nitrogen
If you
take a container of great strength,
fill it to the brim with liquid nitrogen,
seal the container, and
heat it to room temperature.
What will the pressure be inside?
Bonus: The same with liquid Helium.
(I posted this
Reference for phase…
hpekristiansen
- 1,460
11
votes
3 answers
What is the topology of a phase diagram?
Looking at various two-variable phase diagrams I was struck by that on every one I have seen so far all the phases formed simple connected regions; see, for example the phase diagrams of $H_2O$ or of $Fe-Fe_3C$ in 1. Every phase is a connected…
hyportnex
- 21,193
10
votes
1 answer
Phase diagram of simplified QCD
Consider QCD with a single generation of massless quarks (u, d). This is probably the simplest variant of QCD which bears some relation to the real world. The theory has the following exact global symmetries:
U(1) acting on u and d (baryon…
Squark
9
votes
1 answer
Can any element be a metal?
I was reading that hydrogen can become a metal in some cases, like in Jupiter, and the same for helium. Is this true for all non-metals?
noteaming
- 101
- 5
8
votes
1 answer
Will interstellar helium condense to a liquid as space expands and cools?
Intergalactic space is 2.7K (https://en.wikipedia.org/wiki/Outer_space) Interstellar space is a little warmer. My understanding is that these will decrease over time.
The phase diagrams of helium I can find vary a little bit; eg
but they all show a…
Alex K
- 488
8
votes
3 answers
Simple estimation of the critical temperature of water
I'm trying to develop fermi estimation skills and I came up with a question for which I don't even know where to start from. Here goes:
Is it possible to estimate the critical temperature (say in Kelvin degrees) of water in a simple way using fermi…
Steven Mathey
- 4,425