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Questions tagged [phase-diagram]

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16 views

Surface tension and definition of boiling point

The boiling point of a substance is defined as the temperature at which the vapor pressure of a liquid equals the pressure surrounding the liquid and the liquid changes into a vapor. Does the pressure ...
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0answers
37 views

What to use as reference state for free energy curve of a gas?

My goal is to determine the temperature at which xenon would sublimate (if it didn't turn into liquid first). To do this, I set the free energy of solid Xenon equal to the free energy of Xenon gas, $ ...
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Function to describe changes in water's phase diagram

I measured the barometric pressure over 4 days and I obtained the next image: The Y axis is the pressure in hPa and the X axis is the time (4 days) I think it is very interesting the fact that the ...
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2answers
78 views

Can vodka turn to a solid?

How can I turn vodka into a solid? If I boil it, and then cool completely, will it still be a liquid? Is there any way to turn vodka to a solid?
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1answer
33 views

How to graph the properties of steam?

I need to render this graph in Unity: I'm using this as a resource: http://www.iapws.org/ I've found various implementations of IAPWS (95, 97, etc...) in various languages (python, c++, fortran, ...
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Does anyone knows where can I find the phase diagram of oxygen free copper (OFC or OFHC)?

I am having problems with a niobium deposition I made on a substrate. I increased the temperature to 500 degrees celsius and in theory the film should have a better quality. However this wasn't the ...
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3answers
158 views

Shape of isotherms in $P$-$V$ phase diagram

Please explain the shape of the isotherms in this P-V phase diagram. In particular, why are the isotherms flat in the liquid-vapor region? (image from Lumen Learning | Physics | Phase Changes)
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How are drawing common tangents to get diffusion different for concave and convex phase fields?

Whenever there is a concept of diffusion involved and we need to decipher what is going to happen we tend to draw common tangent s in the phase field diagrams and decide which direction the diffusion ...
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1answer
57 views

Why doesn't the phase diagram of water look different?

How can sublimation occur at much lower temperatures than 0 degrees celsius provided that the pressure is sufficiently low? The melting point of water is relatively unaffected by the external pressure ...
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45 views

Thermodynamics, Phase change diagrammes

What would be the phenomena and PV, TV diagrammes for a closed vessel partially filled with water and subjected to heat, How change in vapour pressure would effect its boiling?, How PV, TV diagrammes ...
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28 views

Phase diagram of a fluid

How is it look like the phase diagram of a fluid in density-pressure plane? I came across the phase diagram in Pressure-temperature plane most of the time. But I can't find the phase diagram in ...
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38 views

Applying the Clausius-Clapeyron relation

An example of the Clausius-Clapeyron equation, according to Wikipedia, is: I'm a bit confused with the process. As far as I'm concerned, this slope is the rate of change of pressure with respect to ...
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1answer
137 views

How to interpret phase diagrams?

I find quite difficult to interpret phase diagrams in general, for example I see people discuss them along the following lines: Here we see the coexistence line between liquid-solid phases.. a ...
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0answers
87 views

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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1answer
80 views

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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3answers
230 views

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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2answers
148 views

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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1answer
99 views

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
86 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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1answer
80 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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2answers
175 views

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
2k 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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1answer
200 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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0answers
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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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1answer
65 views

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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211 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
55 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
158 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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1answer
774 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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45 views

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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1answer
60 views

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
18k views

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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2answers
427 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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1answer
102 views

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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3answers
567 views

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
32 views

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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4answers
6k views

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
130 views

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
43 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
874 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
697 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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2answers
70 views

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
383 views

Phase diagram mixture nitrogen oxygen

Consider a phase diagram of Oxygen Nitrogen. Now my question is : if a take a box containing air (80 % N2 - 20 % O2) at standard pressure and I start cooling it from room temperature to -196°C (BP of ...
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2answers
85 views

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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3answers
149 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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0answers
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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 ...