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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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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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494 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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78 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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62 views

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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437 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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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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56 views

Phase description for a substance dissolved in a solvent other than water?

I'm trying to write an equation for which I have $\ce{CuI}$ dissolved in acetonitrile. Usually if you have a salt dissolved in water you can denote that using $\ce{(aq)}$, but is there a notation for ...
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633 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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82 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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39 views

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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136 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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348 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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100 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

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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58 views

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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58 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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56 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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29 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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101 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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32 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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34 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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142 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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39 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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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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243 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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675 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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109 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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48 views

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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214 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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37 views

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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25 views

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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471 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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Freezing point depression of salt solutions

I have recently come across this particular equation which is used to estimate the freezing point depression of a salt solution: $$\theta_\mathrm{B} = \frac{\Delta H^\mathrm{fus}_{0,T_\mathrm{F}} - ...
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97 views

Why are Txy diagrams curved for dew point and bubble point?

What is the reason behind drawing dew point curve and bubble point curve as curved (and dew point curved outwards and bubble point curved inwards) for Temperature vs Composition Phase Diagram as per ...
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85 views

How to calculate the enthalpy of fusion at a different temperature?

The heat capacity of liquid iodine is $80.7$ $\ce{J*K^{-1}*mol^{-1}}$, and its enthalpy of vaporization is $41.96$ kJ $\ce{*mol^{-1}}$ at its boiling point ($184.3$ $\ce{^oC}$). Furthermore, the ...
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35 views

Which phase offers resistance when oxygen is being absorbed in strong alkaline pyrogallate solution?

While solving a few questions from interphase mass transfer I came across this question. The question stated that when oxygen is being absorbed from air to water it is a liquid phase resistance ...
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31 views

How many components and phases are in an equilibrium system comprising lead sulfate, lead ions, and sulfate ions?

I am going to calculate the degrees of freedom ($F = C-P+2$) on the following system, but I can't figure out whether we have to take $\ce{PbSO4}$, $\ce{Pb^2+}$ and $\ce{SO4^2-}$ as a single component ...
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63 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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226 views

Freezing of alcohol water mixtures below the triple point pressure of water

What happens when you try to lower the pressure of an alcohol-water mixture below the triple point of water? To give a specific example, the freezing temperature of a 50-50 (by mass) ethanol-water ...
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90 views

Can every liquid pure substance be compressed to solid?

Apart form the fact that liquid are often misleadingly considered incompressible, fact that I recently find out to be true only as an approximation in specific circumstances. I was curious to know if ...
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51 views

Can the experimental mole fraction equal one?

I recently did an experiment on the temperature dependence of phase equilibrium acetone $\ce{C3H6O_{(l)}} \to \ce{C3H6O_{(g)}}$ I'm at the stage where I need to find the experimental mole fraction $\...
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51 views

Literature values for NaCl Eutectic - Calculating the eutectic

For the NaCl eutectic I've seen two values widely used: 23.3wt% NaCl - James G. Speight: Lange's Handbook of Chemistry 2017) 5.1 M NaCl (Marion + Kargel 2008 - Cold Aqueous Planetary Geochemistry ...
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290 views

Will the DNA in a solution containing DNA and water evaporate?

I understand that water will evaporate as long as the partial pressure of water vapor is lower than equilibrium vapor pressure. But I am not quite sure if DNA in a solution can, like water molecules, ...
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75 views

Does this freezing point depression problem make sense?

The solvent is water. Pure water has a freezing point of 0 degrees Celsius. How come, in this problem, the addition of solute results in an elevation of the freezing point from 0 to 0.46 degrees C? Is ...
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31 views

Melting point of Ammonia at 143 psia

I'm currently working on a theory involving ammonia based life, but I need information about the freezing point of ammonia at high pressure to determine several ecological limitations at hand. I've ...
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66 views

Solid/Liquid/Gas Phase Change Energy

If energy is put into a solid, for example ice, and the phase changes, where does the energy go? Does it change the length between molecular bonds or get absorbed when the crystalline bonds break?
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Are open system phase transitions physical equilibriums?

I have been told that phase transitions=physical equilibriums. How can phase transitions be physical equilibriums? For example, if you have liquid water going into gas phase, doesn't delta G have to ...
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61 views

Hydrogen phase transition

A sample of hydrogen at a pressure of 7.10×10-2 atm and a temperature of 26.4 K is compressed at constant temperature to a pressure of 18.5 Which of the following are true? 1. One or more phase ...