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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3answers
450 views

Can precipitation occur in states of matter other than liquids?

This answer to Are precipitation and crystallization both analogous between chemistry and meteorology? discusses the history and use of the term "precipitation" in chemistry. From what I ...
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Is there a way to convert the dissociation constant (Kd) to the Flory Huggins Interaction Parameter (chi) or visa versa?

I'm trying to figure out a way to convert the dissociation constant (Kd, Units: nM) in the form ([A]^x[B]^y)/[AB]into the Flory Huggins interaction parameter (Unitless) but I can't seem to find any ...
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98 views

Partial molar volume of binary mixture

A 2% (weight %) solution of a salt with Mr = 190.6 g mol-1 was prepared at 25 0C. The density of the prepared solution was 1.00926 g cm-3. The density of water at 25 0C is 0.99707 g cm-3, and the ...
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1answer
61 views

Does helium freeze at absolute zero? [duplicate]

Does helium freeze at absolute zero? In theory, it should, since all random motions of particles stops at absolute zero, right?
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Is it easier to mix a solution that is in the liquid or in the vapor phase?

In the article on dilution, Wikipedia has the following statement: The same direct relationship applies to gases and vapors diluted in air for example. Although, thorough mixing of gases and vapors ...
0
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1answer
25 views

The formation of ice crystals on/in frozen food that has been defrosted and then frozen again

I made a mistake. I put my ice cream in the refrigerator instead of the freezer and left it there for a night. I realized my folly the next day. I put it in the freezer. When I took it out, I noticed ...
7
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0answers
59 views

Why does diethylmethylamine have such a low melting point?

According to PubChem, diethylmethylamine has a remarkably low melting point of $-196.0\ \mathrm{^\circ C}$. This is substantially lower than the melting points of dimethylethylamine ($-140.0\ \mathrm{^...
2
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0answers
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Working out energies of hydrogen bonds by comparing chemical potential of vapour and condensed phase - equation derivation

I want to ask a question about working out the energy of a hydrogen bond between two water molecules, $w_{AA}$ using the chemical potentials of vapour and condensed phases. I was reading K. Dill, ...
8
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3answers
3k views

At what pressure will hydrogen start to liquefy at room temperature?

I want to increase a fixed-size object's internal gas pressure by generating hydrogen in it, but I could not find the proper phase diagram for it. So I am wondering how high pressures I can get.
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1answer
40 views

Why is change in internal energy not equal to zero during a phase transition? [closed]

Many books state that when there is no change in temperature $\Delta U$ is equal to zero. Why is this not applicable for phase transitions? I have had this question for a while now and have been ...
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1answer
48 views

Why is the temperature graph sigmoidal in simple distillation of components with very different bps?

I'm writing an organic chemistry lab report on distillation and I thought I understood this, but the more I look at my lab textbook, I realize I don't. My textbook 1 explains that the temperature of ...
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1answer
51 views

Brittleness of Ice?

I am curious as that I know that various materials can be subjected to fragility from ductile-brittle transition via temperature, where an item is more likely to fracture of shatter such as increase ...
3
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1answer
19 views

Formulations for wax thermostatic element for effect in alternative temperature range

Wax thermostatic elements are used automobile cooling systems and anti-scald mixing valves to control flow rates or to adjust mixing of flow inputs. These devices operate on the principle of thermal ...
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0answers
38 views

Does fractionation use enough heat to destroy nutrients in Coconut Oils when seperating the MCT oils?

We have recently been giving MCT (medium-chain triglyceride) oil to our dogs in place of Coconut Oil as from what I understand the majority of the benefits of Coconut Oil comes from the MCT's ...
0
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1answer
35 views

Place cooling bath apparatus in freezer to speed up the process?

As part of an at-home lab, my chemistry class is creating cooling baths to measure the freezing point of different solutions. We have to determine the molar mass of the solutes in these solutions by ...
2
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3answers
80 views

Does the temperature during ice melting change? [duplicate]

I did an online test for physics and one of the questions was: Salt was added to ice. Because of it the ice melted. What was happening with temperature DURING the process of melting? The right ...
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0answers
67 views

Freezing point of solution of Water, Ethanol and Sugar (aka, Limoncello)

I'm looking for a diagram of the freezing point of a water solution depending on its content in sugar and ethanol. More colloquially, I want to know how to balance alcohol and sugar so that my ...
2
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1answer
47 views

Predicting sign of enthalpy of allotropic transition of phosphorus

How to predict the sign of enthalpy during the transition $$\ce{P(s, white) -> P(s, red)}?$$ $\ce{P(s, red)}$ is more stable than $\ce{P(s, white)}$ due to release in angle strain. Since during ...
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1answer
80 views

Latent heat of vaporization/evaporation

It's the amount of heat required for liquid ---> gas phase change of a substance at it's Boiling point. But my question is, does providing energy equivalent to latent heat of vaporization to a ...
2
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2answers
139 views

Internal energy for Phase Transitions

Can we justify that "For sublimation of a solid at 1 atm $\Delta U>0$ at low temperature and $\Delta U<0$ at high temperature?" I read several answers and came to know that $U=f(T)$ ...
6
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2answers
335 views

Why is the molar entropy of hexane lower than that of butane?

Entropy is dependent on the complexity of the molecule. Due to this, I expected entropy to increase as the complexity of the molecule increased. According to p 918 of Atkins' Physical Chemistry (9th ...
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1answer
55 views

Molality of solution to be used when finding water separated from solution as ice

Question $\pu{1 kg}$ of a solution of cane sugar is cooled and maintained at $\pu{-4 ^\circ C}$. How much ice will separate out if molality of solution is $0.75$? $K_\mathrm{f} \ \text{(water)} = 1....
2
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1answer
48 views

What is happening at the various boundaries of a phase diagram? [closed]

Hoping to clarify a few questions I have that the textbook doesn't address. Lets just say I have a piston (at equilibrium) with 100 moles of gaseous compound that looks like this: And here is the ...
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1answer
33 views

Aluminium oxide phase diagram

I have been looking for the phase diagram of alumina or Aluminium oxide, could it be that there is not something like that? thank you
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2answers
446 views

What happens to boiled (BMIM)PF6?

[BMIM]PF6, or 1-butyl-3-methylimidazolium hexafluorophosphate, is commonly used as an ionic liquid. As has been shown by the accepted answer to this question, sodium chloride that has been made to ...
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1answer
70 views

Does the depth of a lake affect how quickly its water is evaporated? [closed]

Suppose there are two freshwater lakes, each with identical surface areas and circumferences. One lake is 1 ft deep and the other is 20 ft deep. Although they exist in nature, lets assume they are ...
3
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1answer
739 views

Can silicon dioxide melt at 20 °C?

Can $\ce{SiO2}$ melt at $\pu{20 ^\circ C}$? I have searched the web for $\ce{SiO2}$ phase diagram, but it seems to me that almost all the graph I can find have the temperature axis where the minimum ...
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0answers
32 views

How to measure deuterium concentration in DDW at home when you try to DIY DDW from freezing process?

I tried to automatize the Deuterium Depleted Water (DDW) receiving from the freezing process, but the result can be reached only after deuterium concentration measurement. Anybody knows how to make it ...
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0answers
29 views

Lowering the freezing point of a lipid by adding another lipid

I'm trying to stop bacon grease from congealing in the fridge by adding another lipid with a lower freeze point to it, but I'm not sure how much to add, as I'd like to keep the ratio as bacon-grease ...
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2answers
30 views

Doubt concerning Andrews Curve [closed]

In Andrews Curve of $\ce{CO2}$, what do the horizontal lines signify? I know that the gas changes to liquid in that region, but since the pressure and temperature is held constant, how does the gas ...
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1answer
85 views

Clausius–Clapeyron equation: shape of phase diagrams makes no sense

I am trying to model the melting point of a substance at varying pressures (ranging from very small to very very large). All I am trying to do is make an equation that relates melting temperature to ...
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1answer
43 views

Vapour pressure of a liquid subjected to pressure

I am following the derivation by Atkins in section 4B(c) (Physical transformations of pure substances; thermodynamic aspects of phase transitions), in which the authors derive the equation ${p = p_* * ...
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1answer
64 views

What is heterogeneous catalysis in gas phase?

Give examples of heterogeneous catalysis (i) in gas phase and (ii) in liquid phase. Now, I came to know that heterogeneous catalysis involves different phases between the catalyst used and the ...
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2answers
43 views

Effect of pressure on transition temperature

I was wondering if someone can explain why the answer to the following question is volume instead of the others. If pressure has no effect on the transition temperature between two crystalline forms ...
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2answers
282 views

What does the phase diagram mean by “liquid” at NTP? (The liquid and vapor coexist even when the situation is not on the curve)

[Solved. For anyone who is also confused, see the comments under Poutnik's answer. As Poutnik reminds me, remember there is no air involved. I successfully picture that with the piston experiment in ...
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0answers
48 views

can a vapour denser than air evaporate in a closed chamber? [closed]

Imagine a closed container filled with air. There is some liquid substance on a bottle placed on the floor of the container. Let's heat the liquid until it starts to evaporate. Let's say 20% of the ...
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0answers
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Formulation chemistry. Can somebody suggest me an introductory book on this subject? [duplicate]

I am looking for an introductory book on formulation chemistry: the book should cover physico-chemical aspects in designing a formulation and also, if possible, the chemometric basic concepts used in ...
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1answer
29 views

Does toxicity depend on state of matter? [closed]

Does the toxicity of an element depend on the state of matter (liquid, solid, gas)? Could there be an element, which is totally non-toxic when it is solid, but toxic when it is liquid. Which elements ...
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1answer
43 views

Is ethane or carbon dioxide easier to liquify? [closed]

Let's say $\ce{CO2}$ and $\ce{C2H6}$ are both in gas form, not vapour. Now which one will be easier to liquify? My take is that the molecule of $\ce{C2H6}$ should be much larger than $\ce{CO2}$ and ...
4
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2answers
263 views

Why can't Carbon Dioxide be liquid at 1 atm?

Wikipedia says that Carbon Dioxide cannot be liquid under atmospheric pressure. I thought the phase of an element was related to both pressure and temperature. If that is so, then should you not ...
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0answers
40 views

Liquid neon freezer?

Liquid nitrogen is approximately -330 degrees Fahrenheit. Liquid neon is approximately -413 degrees Fahrenheit. I want to know about if this type of freezer is easily possible in practice and if such ...
0
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1answer
112 views

Is there a phase diagram available for hydrogen fluoride?

Has a phase diagram for hydrogen fluoride been published in an article on the internet or in a book ? Or is there a table for HF for different pressures up to 100 atm. and temperatures up to 500$⁰$ C ...
3
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0answers
162 views

Is the active mass of every solid and liquid taken to be unity?

I learnt from my textbook and the question/answer - Why is active mass of a pure solid or liquid always taken as unity? that active mass of a solid or liquid is taken to be unity as: $$[A]=\frac n V=\...
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1answer
24 views

Difference between a species and a phase in a solution? [closed]

Overview: As of my knowledge from metallurgical thermodynamics a phase is a thermodynamically stable and homogeneous entity made up of different species of a given concentration. e.g = 'Austenite' ...
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0answers
39 views

Is kinetic energy proportional to temperature for non-gases?

If the molecules in a sample of ice at $\pu{-15 °C}$ and $\pu{1 bar}$ all have their kinetic energy doubled, then what is the final phase? The answer is gas, but I am not sure how to get this answer. ...
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0answers
17 views

Two-Phase Pressure Drops in Screen-Plate Bubble Column

I am reading the paper A Correlation of Two-Phase Pressure Drops in Screen-Plate Bubble Column The goal of the paper is to come up with a regression model for a correction factor (denoted $K$) for a ...
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1answer
62 views

Isothermal transforamtion diagram - Austentite [closed]

A steel alloy is rapidly cooled to $\pu{600^oC}$, held for $\pu{4 sec}$, rapidly cooled to $\pu{450^oC}$, held for $\pu{10 sec}$ and quenched to room temperature. What phases are produced? Why is ...
0
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1answer
140 views

What is the mass fraction of C2HCl3 in the liquid phase using vapour pressure and mole fraction in gas phase?

Vapour-liquid equilibrium of a two-component ideal solution of trichloroethene ($\ce{C2HCl3}$) and trichloromethane ($\ce{CHCl3}$) is established at $\pu{25 °C}$. The mole fraction of $\ce{CHCl3}$ in ...
1
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1answer
65 views

Why does eutectic point have three phases, but consolute point have only two phases?

At eutectic point, there are three phases: solid A, solid B and homogenous liquid phase containing both A and B. But at consolute point, we are told it has 2 phases: liquid A and liquid B. Why isn'...
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2answers
125 views

Why when deriving the Clapeyron equation can you assume that dH = dq, as surely the pressure is not constant?

Part of the Clapeyron equation involves replacing $\Delta S$ with $\Delta H/T$. I can see the step from $\Delta S$ to $\Delta q/T$ but I'm not sure why you can replace $\Delta q$ with $\Delta H$. From ...

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