Questions tagged [phase]

An entity of a material system which is uniform in chemical composition and physical state. This tag should be applied to question regarding chemical and physical properties of phases, systems of phases and also phase transition processes.

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What happens when para-water ice is suddenly melted?

Background (hydrogen) In the case of recently liquified hydrogen (which is quite cold of course) it must be re-equilibrated before loading on to a rocket as fuel to avoid a sudden exothermic ...
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340 views

Is helium-4 a liquid at zero temperature and zero pressure?

As far as I know, for all substances other than helium, if you extrapolate the solid-gas line on the phase diagram, it passes through the origin. That is, no matter how low the temperature is, you can ...
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572 views

Vapor-pressure or Vapor-concentration

To summarize from my textbook: rate of evaporation: proportional to surface area but essentially independent from pressure (of surrounding gas) rate of condensation proportional to both surface ...
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84 views

Describing evaporation without entropy — what about Helmholtz?

I have in mind a rigid, impervious, heat-insulating vessel containing a monatomic liquid and vacuum. The vessel has an insulating forcefield inside, exactly at the surface of the liquid. It can be ...
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36 views

How are phase transition diagrams calculated?

How are diagrams such as above plotted? Since empirical studies are slightly off from the 'ideal', what is the source for the phase plots?
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Can anyone explain this condensation pattern?

What is the hair-like polymer that condenses on the caps of the plastic cell vial? Inside vial are cells in a mixture of FBS and DMSO. The vials were frozen slowly in a special isopropanol-filled ...
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593 views

State symbol for electron

Is it correct to write a state symbol of "g" or "l" for an electron? In the textbook I am currently reading, the state symbol "g" was used for the electron when it described the electron gain by a ...
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29 views

What dynamical features allow for the existence of a liquid-liquid transition?

Recently it has been shown theoretically[1] and then experimentally[2] that a liquid-liquid transition (LLT) takes place in pure supercooled water. That is to say, two distinct liquid phases have a ...
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171 views

Clausius–Clapeyron relation for states of water and vapor

I've seen many questions about this topic on this site, but I still have some issues trying to understand this aspect. Here's what I believe I understood looking at the phase diagram for a pure ...
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732 views

Determining pressure of sublimation of iodine

The pressure of sublimation of iodine can theoretically be determined by considering the two hypothetical steps: the sublimation of iodine at $\pu{298 K}$, followed by an isothermal expansion of our ...
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113 views

Dilution of whisky – the molecular perspective

Not a chemist. I'm trying to understand this abstract. In particular: We found that guaiacol is preferentially associated with ethanol, and, therefore, primarily found at the liquid-air interface ...
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Chemical that won't freeze below melting point

I have an organic chemical (can't say due to an NDA) that has a nominal melting point of 28 °C. When I raise it above this temperature, it melts, but then it will stay a liquid indefinitely at lab ...
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127 views

How to without calculations understand the liquid-liquid extraction efficiency?

I'm asking myself this question for a very long time and I haven't found a simple an good explanation yet for the fact that it's better (if you want to clean them) to wash your hands two times with ...
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290 views

Given this liquid-liquid phase diagram, is the green line the nitrobenzene-rich phase?

The temperature-composition diagram for hexane and nitrobenzene at 1atm. The region below the curve corresponds to the compositions and temperatures at which the liquids form two phases. The upper ...
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Looking for a pressure phase diagram of selenium at large ranges of pressure and temperature

I'm doing undergraduate research and our group is having a lot of difficulty finding a comprehensive pressure phase diagram or phase table for selenium (including most known packing geometries that ...
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211 views

Reforging tungsten/tungsten carbide temperatures

I was wondering about the reforging of tungsten and the temperature needed. As I understand it, tungsten melts at $\pu{3442 ^\circ C}$ and tungsten carbide at $\pu{2870 ^\circ C}$. However, once a ...
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452 views

How to measure chemical potential

I wonder if there is a way to measure the chemical potential of a substance in a two-component mixture and also to account for its dependence on the number of moles. Explaining it further, suppose ...
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125 views

Properties of metallic hydrogen

Given the possibility that metallic hydrogen may have recently been produced, and the massive media bloviation that followed, I am curious about some of the "properties" that I heard from multiple ...
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1k views

Why is phenol a solid at room temperature?

The commonly cited reason is inter-molecular hydrogen bonding. But won't the hydrogen bonding in phenol be weaker than that of most alcohols because of resonance-effect? And yet, alcohols with ...
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Heat capacity during state change

I read that the heat capacity of water when it is at 100 °C or 0 °C is infinite because all the heat given to it will not be used to increase temperature but to change the state. I am unable to ...
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Generating Precipitation Diagrams with CompuTherm Pandat

I am trying to develop precipitation diagrams for an Ag-Cu-Sn alloy to figure out the kinetics involved using the CompuTherm Pandat Software (Demo Version). The precipitation diagrams need the ...
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Can amorphous polymers have a melting temperature as well as their glass transition transition temperature?

Above the Tg, amorphous polymers are described as viscous liquids. What then would they be likened to above their melting point, should they have one?
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Is there any sort of correlation between melting point and the degrees of freedom for the molecules of a substance?

Suppose I had a solid whose molecules did not have rotational freedom. But if I were able to make it so that the molecules had rotational freedom ceteris paribus, is there a way to tell how the ...
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29 views

Reaction that will produce a silica coating (glaze)

The normal way to create a coating of pure silicon dioxide glaze is to coat the object to be glazed in a slurry of silica particles and then put it in a kiln. However, if I have an object that is too ...
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147 views

What's the density of a frozen ethanol or ethanol solutions?

How can we know what's the density of ice (water), but there's no data on how much is the density of frozen ethanol? (as far as I know)
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99 views

How to determine the phases in a complex phase diagram?

In my school notes, we have the following phase diagram that shows an example of how complex things can get when we have intermediate phases. I tried filling in phases, but I have no idea how to check ...
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72 views

What causes both components of a binary gas mix to condensate at the same time for a given composition

Okay, so recently I encountered the temperature - mole fraction diagrams for binary vapour-liquid equilibrium. For now, I only consider two-component systems where the components are very similar and ...
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32 views

Why do frozen whipped cream remain “frozen” when thawed?

I froze some pastry with whipped cream on the other day (by mistake, I placed it on my balcony and expected it to be a few degrees above zero, but it wasn't). When I unfroze it again I was expecting ...
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127 views

Why does CO2 only exist in gaseous and solid state under STP/SATP?

Why does carbon dioxide only exist in gas and solid state under STP/SATP conditions? $\ce{CO2}$ pressurized to $\pu{5.1 atm}$ can exist in all 3 states: solid, gas, and liquid. However, why couldn't ...
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33 views

Do all supercritical fluids dissolve the same substances?

In the case of regular fluids, polar solvents dissolve polar molecules and nonpolar solvents dissolve nonpolar molecules. Is there something analogous for supercritical fluids? In other words, does ...
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37 views

Equilibrium involving water and solid component

$$\ce{A + B <=> C(s) + H2O(l)}$$ Why when $\ce{H2O}$ is liquid and $\ce{C}$ is solid, the equilibrium constant of the reaction is $$K_\mathrm{eq} = \frac{1}{[\ce{A}][\ce{B}]} \quad ?$$
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163 views

Anhydrous ammonia vapor-liquid equilibrium

I have been given a anhydrous ammonia vapor liquid system in an air-tight container where the pressure is 30 bar and the temperature is 30 degrees. They claim the system is in equilibrium, which I ...
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42 views

What type of catalyst would this be?

We were discussing types of catalysts, homogeneous and heterogeneous. Our question is: If you have two reactants, one reagent is aqueous and the other is a gas, and the catalyst is aqueous, what type ...
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60 views

Is it possible to supercool hydrated salts like magnesium nitrate hexahydrate supercool just like for sodium acetate trihydrate?

Recently I stumbled upon the phenomenon of supercooling. I know that you can do this with water as well as with some phase change materials, like sodium acetate trihydrate (from the wintersport ...
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294 views

Water condensation above dew point

Anyone who stores rust-prone instruments knows that even in temperature-controlled air spaces rust can form on uncoated steel. Since rust requires water, this suggests that water will condense out of ...
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796 views

How can I estimate the triple point of a substance given the densities of its liquid and solid phases and its enthalpies of fusion and vaporization?

I am trying to find the triple point of H2O given only the densities of water and ice, the enthalpy of vaporization, and the enthalpy of fusion. I know that I should be able to use some combination ...
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121 views

Effects of inert gas on heterogenous equilibrium

What is the effect of the presence of an inert gas on a reversible reaction that was in more than one phase, such as a decomposition reaction? If a solid or liquid or compound in aqueous solution ...
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Why is including phase info in chemical reactions important?

I would like to ask why do we have to include the phase change in a chemical reaction e.g from solid to aqueous or liquid. Why is it important actually?
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248 views

What are the physical properties of exotic ice?

This chart shows the phases of water that form at various combinations of pressures and temperatures. It has multiple exotic forms of ice (labeled II through XV) listed. What are the physical ...
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Equilibrium saturation/depostion rate calculation

I found the Knudsen/Langmuir equation for calculating the sublimation rate of a solid. If I have a closed system, once the vapor reaches the saturation pressure, the solid will continue sublimating ...
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Fluid Separation

I've been trying to find a way to prevent cornstarch and water from separating. If I'm right, emulsifiers are used to prevent fluid seperation with oils, but will an emulsifier fix my problem too? If ...
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520 views

High quality phase diagram for ethanol

I know the more general question has been asked here: Open Database of Phase Diagrams? And this has a link to slightly more specific question with more answers: Phase diagram for first 10 elements ...
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Deformation of the nematic phase of liquid crystals surviving in the solid state

Does anyone know if I were to cool a liquid crystal with a deformed nematic phase quickly, if it will preserve the deformation in the crystal lattice? I didn't find any information in classical ...
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183 views

Nucleation and Phase Equilibrium at the Melting Temperature

I used to think that at the melting point, the solid and liquid phases are in equilibrium. That’s because the Gibbs free energy change for the transformation is 0, as is characteristic of equilibria. ...
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Data of phase diagram of water?

I am trying to build a mathematical model that represents the curves of a phase diagram. Is there somewhere I can find the data points of the phase diagram of distilled water?
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Diffusion between phases based on chemical potential

How is the concept of diagram(b) different from that of (e) and (d) from (f)?Someone told me in one of my earlier posts (Why will A atoms diffuse from β phase to α phase and B atoms from α phase to β ...
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Phase Diagram-Fe-C, and TTT: Hardness Scale

So far I know that the Hardess scale of these materials is this: Martensite> Bainite> Perlite > Cementite> Ferrite Where is Austenite along this scale? I know that Cementite is harder than Austenite....
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Can we estimate if a substance will be in gas state at certain temperature?

Sometimes, by ballparking, we can estimate that a certain substance isn't in the gaseous state at room temperature because it has a large molecular weight. There is a direct relation between ...
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Will evaporation from two immiscible liquids blow up a balloon?

Consider the following setup: Two immiscible liquids A and B are placed inside a balloon at a temperature where neither one of them boils. The inside of the balloon contains some argon, and the ...
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Eutectic Phase Diagram of Al-Si Analysis

Hello, How can I know from this phase diagram: 1. The composition of the alloy Al-Si that allows precipitation to occure? 2. The range of temperatures where the Al-Si is soluble? 3. The range of ...