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Questions tagged [phase-diagram]

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Why does placing liquid nitrogen in a low pressure chamber lower its temperature?

As you can see in this demonstration and read in this Wikipedia article if you were to place a cup of liquid nitrogen in a low pressure environment then it would reach a triple point and begin to ...
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Is the triple point of water exactly 0.01 $\deg$C?

Is the triple point of water exactly $0.01 \deg$C, or is this an empirical value/is there some uncertainty to it? If so, how do we know it is exact, and why?
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What's the difference in a PV diagram that is curved versus one that is straight?

So what would the difference be between the graph above versus one that has the same inital and final points but the path is curved. I'm sure it has something to do with temperature, so does it mean ...
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Viscosity table or diagram for melts of oxides

Is there a table or diagram to relatively determine which oxides have low 'melt-viscosity' (i.e relatively flow readily when melted)? Is it possible to determine such property based on phase diagrams ...
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Is it possible to have a planet entirely made out of liquid water?

Earth is mostly covered in oceans, but they only go a few kilometres deep. It's obviously not possible to have a planet the size of the earth to be made entirely out of water, because of the kind of ...
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Multiple Triple Points

I was reading Chandler's Introduction to Modern Statistical Mechanics and noticed a strange feature in one of the figures. The phase diagram in the image has two triple points; however, according to ...
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1answer
71 views

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 $...
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54 views

Is there a temperature-pressure phase diagram of carbon dioxide for the lowest temperatures and pressures?

The image above will probably be well known to visitors of Wikipedia on CO$_2$. But is there a temperature-pressure phase diagram of CO$_2$ for still lower temperatures and lower pressures as well ?...
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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?
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Can phase transitions occur in open systems?

Is it possible that in open systems can occur phase transitions if the required conditions (i.e., temperature and pressure) are met? Are there examples?
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1answer
695 views

Are saturation temperature and boiling point same thing?

In my view they both are same thing. Boiling point is the temp at which vapor pressure of water becomes greater than pressure outside vessel. Liquid water change it's phase during this. And. At a ...
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107 views

Definition of boiling point of water

As we all know at normal boiling point, vapor pressure of water is equal to atmospheric pressure. Vapour pressure of water is pressure exerted by its vapor(in dynamic equilibrium with water) on the ...
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Is $H_2O$ the only compound which has a density anomaly? [duplicate]

My question is simple: are there any elements, compounds or materials other than water ($H_2O$) which have a density anomaly characterized by a turning point in the $T-\rho$ curve?
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Phase of refrigerant when entering evaporator?

In the diagrams for refrigeration cycle(vapour-compression), the refrigerant at the inlet to the evaporator lies under the vapour dome i.e partly vapour and partly liquid. Now i have been studying ...
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138 views

Data for plotting phase changes in water

I want to plot phase diagrams of water that show its density, heat capacity, and entropy as it undergoes various first order (discontinuous) phase transitions with increasing temperature. I'm ...
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1answer
54 views

Does carbon form a gas in the absense of oxygen?

If I take pure carbon and heat it in an inert atmospher, at what temperature will it vaporize into carbon gas?
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1answer
120 views

Why should the vapor pressure exist at all tempratures?

According to P-T phase diagram, at a constant pressure, liquid and gas attain equilibrium only at a certain temperature, (i.e. boiling point). So in a situation where I'm keeping a liquid in a closed ...
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491 views

What is the difference between vapor and liquid with same temperature?

When the temperature is same, it means that the kinetic energy of the particles of both phases are the same, so what is the difference between a vapor and liquid of a substance, such as ethanol, when ...
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Is there a material that boils when heat is removed at constant pressure?

Echoing the marvelous question of a material that freezes when heat is added at constant pressure, I am wondering whether there is a material that would boil when heat is removed at constant pressure. ...
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Finding phase diagram in the region of unstability

I have a question regarding the construction of following phase diagram : (Above image is taken from the book Thermodynamics in Material Science by Robert T. DeHoff) In the above diagram (a binary ...
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Phase evaluation in complex periodic functions

I need to evaluate how out of phase are two complex periodic functions that have the same frequency. Two examples of pairs of periodic functions are depicted in the figures.
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1answer
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Converting units, ternary phase diagram [closed]

I have a task with a ternary phase diagram with units given in mol/mol, but in the description I am also given a feed-to-solvent ratio at 2.5 kg/kg. The molecular masses (and in the equation you see ...
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2answers
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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 ...
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279 views

Pressure-temperature dependence of a pure substance

Saturation temperature is defined as the temperature at which a pure substance say water, changes phase, at a fixed pressure. So water boils at 100⁰C , if the external pressure is kept constant at 101....
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Is the $\lambda$ point in superfluid helium understood?

When liquid helium is cooled below a certain temperature, it undergoes a second phase transition from He I to He II. The specific heat spikes at the famous lambda point. Is this spike in the specific ...
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Meaning of the term “phase” in chemistry and thermodynamics

I have some doubts about the definition of the term “phase” in chemistry and thermodynamics (is the meaning the same?). The "textbook" definition is: "A phase is a form of matter that is uniform ...
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1answer
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When plotting phase plane portraits are constants considered equal?

The phase plane representation of the system, [x';y']=[1,-1;3,-1][x;y], would be concentric ellipses about the Eigen vectors. But, in the case that the constants C1 and C2 are different, can't these ...
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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 ...
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1answer
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Phase diagram. When will I have a phase transition?

Take this phase diagram : At the point "A" I will have a liquid, at point B a gas. But what I want to know is : which phase do I have at point C. I know that this is precisely where the phase ...
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1answer
39 views

resonanting frequency phase [closed]

I know phase at resonating frequency is Zero!! Now the question is, can anyone help me to prove it. I was looking for a better clarification with diagrams that can help me grasp the concept.
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1answer
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Can I ice skate on toluene?

I thought about that can I ice skate on toluene? We can ice skate on ice but can we do it on ice? Please help me it would be helpful for me
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2answers
677 views

Is water vapor in a metastable state at 1 atm and at room temperature?

At 1 atm and room temperature, is water vapor in a metastable state? As I understand it, water vapor is water in a gaseous state when the stable phase of water under this temperature and pressure is ...
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1answer
364 views

Pressure-Volume Diagram

Why does pressure start off high in the Pressure-Volume Diagram starting from a compressed liquid to a super heated vapor? Noting that the temperature is constant in the process,I can't seem to ...
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2answers
2k views

Phase diagram of water

In the phase diagram of water, in relation to the gas phase region and bordering lines, what is the relevant pressure? Is it the partial vapour pressure of water, or is it the total pressure including ...
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Phase diagram surfaces

When looking at the 3D phase diagram of water I felt unsure whether the only physical points were the ones on the surface of the plot. If it is unphysical to move outside the surface of the phase ...
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1answer
324 views

Phase diagram mixture nitrogen oxygen

At this page, the phase diagram of Oxygen Nitrogen can be seen http://liquidair.org.uk/full-report/report-chapter-nine Now my question is : if a take a box containing air (80 % N2 - 20 % O2) at ...
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Meanings of the word “phase”

I have been confused at points due to multiple uses of the word "phase". Mainly, when I think of a phase diagram, I think of a graph relating temperature to pressure, and segments the possible ...
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2answers
107 views

What exactly is the driving force of a vapor turning into a liquid once it tips just above the saturated state?

I'm a first timer here. In a normal liquid-vapor P-V biphasic curve at a temperature below critical temperature, we can compress a vapor at a constant temperature till it becomes saturated, or is just ...
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Phase diagram of $\text{He}^3$ at low temperatures

The $p(T)$ phase diagram of $\text{He}^3$ at low temperatures is given here: https://de.wikipedia.org/wiki/Pomerantschuk-Effekt#/media/File:Phasendiagramm_He3log.gif How can one physically explain ...
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Why does temperature remain constant at the boiling point of the liquid? And what kind of an equilibrium is boiling?

When we were in school, the teachers used to tell us that heat increases the kinetic energy of the particles (reflected in the temperature) until the boiling point is reached. Afterwards, all the heat ...
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1answer
580 views

Goldstone bosons, quark and gluon masses counting in color-flavor locking QCD

Consider QCD, with three flavors of massless quarks, we like to focus on the possible Cooper paired phases. For 3 quarks $(u,c,d)$ and 3 colors $(r,g,b)$, the Cooper pairs cannot be flavor singlets, ...
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I need the phase diagram for ethanol [closed]

I have been googling for a while and I cannot find a phase diagram for ethanol. Does anybody know of a site that has it? Is there something I should be googling other than phase diagram for ethanol? ...
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1answer
322 views

Why are eutectic transformations considered incongruent?

A eutectic reaction is one in which, upon cooling, a liquid transforms to two solid phases: L --> A + B My textbook defines a congruent phase transformation as: "A transformation for which there ...
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1answer
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How cold can a pile of dry ice nuggets get inside of a vented insulated box?

The question: Dry ice sublimates at -78.5°C at sea level pressure. So how can I be measuring temperatures as low as -90°C within the box? The setup: The box is at sea level and is sealed to be gas-...
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Shifting of minimas in transmission spectrum due to phase transition

Given is the following transmission spectrum of heptadecane for different temperatures: Approximately at $T = 294.5\,\text{K}$, there is a phase transition from liquid to solid. Now, one can see ...
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Intensity of light and phasors

I have now been learning about interference through slits, and we considered a phasor approach to this. I notice that the intensity detected on the screen was the square of the net phasor at that ...
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1answer
463 views

Direction of the wavevector?

According to this website and several other websites I have come across, the wavevector direction is in the direction of wave propagation. On the other hand, Wikipedia suggests that The direction ...
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1answer
80 views

Superposition of waves: why do they not cancel?

I am not sure what I am doing wrong here or if I have made some wrong assumptions, however my intuition is contrasting with my mathematical result. I am considering a case where there are two ...
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Phase diagram of the Z_N-invariant clock model

A well-known 1985 paper by Fateev and Zamolodchikov "Nonlocal (parafermion) currents in two-dimensional conformal quantum field theory and self-dual critical points in Z_N-symmetric statistical ...
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Phase diagram for water

The phase diagram for water shows that at very high pressure and room temperature water becomes ice. Is it possible to this confirmed this by experiment?