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.
487
questions
0
votes
0
answers
37
views
Do we group reversible reaction with all reactants and product solid as homogenous or heterogeneous equilibrium?
My personal thought is that they should be in heterogenous equilibrium as we define it as all reactants and products being of different phase (phase-their must not be a visible boundary) and solids ...
- 1
2
votes
2
answers
76
views
Fractional Distillation Question
We're covering fractional distillation in my physical chemistry class. I'm confused regarding this diagram:
From your starting point, you heat the binary mixture (in this case benzene and toluene) to ...
- 309
0
votes
1
answer
56
views
Sign of ∆S in conversion of diamond to graphite
It is said that ∆S is positive as randomness is increasing from diamond to graphite as in diamond molecules are tightly packed together but we know that ∆S=∆H/T for phase transition and that ...
- 33
-3
votes
1
answer
75
views
Liquification of ideal solution of two liquids from vapor phase [closed]
A and B form an ideal solution. In a cylinder piston arrangement, $\pu{2.0 mol}$ of vapor of liquid A and $\pu{3 mol}$ of vapor of liquid B are taken at $\pu{300 torr}$ and $T~\pu{K}$. At what ...
0
votes
0
answers
45
views
How can two separate phases interact with each other in an separatory funnel
Hello I was thinking about the following process.
I was working in the lab, and synthesized a chelator for various metals, iron, copper etc.; however, when extracting the mixture with water and ethyl ...
- 277
6
votes
0
answers
110
views
Which xylenes, if any, are immiscible with DMSO?
"Xylene" is reported to be immiscible with dimethyl sulfoxide (DMSO), according to a few solvent miscibility tables found online (chart 1, chart 2, chart 3). I have tried to locate some ...
- 792
6
votes
0
answers
60
views
Is gallium slippery at room temperature in an inert atmosphere?
Ice is slippery when it isn't too far below it's melting point because the surface molecules are less loosely bound than the bulk and form a thin liquid layer.
Pressure melting is a much smaller ...
- 784
2
votes
0
answers
48
views
How do I plot ternary phase diagrams using Flory-Huggins solution theory?
I have three components, $A,B,C$, with 3 exchange parameters: $\chi _{AB}, \chi _{BC}, \chi _{AC}$. I want to create a FH ternary diagram to see how such a mixture behaves and how phase separation ...
- 121
5
votes
1
answer
211
views
Why can't the change in a crystal structure be due to the rotation of octahedra?
I have the following information about barium titanate ($\ce{BaTiO3}$).
It adopts the perovskite structure and
has a phase transition from a cubic to a tetragonal phase at 120 °C.
The space group of ...
- 61
2
votes
1
answer
53
views
Are there distinct phases of amorphous ice?
Amorphous ice is a solid phase of water that lacks crystal structure. It is stable below about 150K, above which it converts to crystalline ice.
There are four phases of amorphous ice: low medium, ...
- 784
-4
votes
1
answer
72
views
What is the relationship between solutions and changes to states of matter?
For example, when liquid water evaporates, my instinct is to say that of course it's become gas, but I'm a bit unsure because, if I understand correctly, evaporation occurs because air dissolves the ...
6
votes
1
answer
436
views
Does "brine rejection" happen for dissolved gases as well?
"Brine rejection" is the effect of sea ice pushing out dissolved salts, forming sweetwater ice and brine. I understand "freeze distillation", a method to concentrate alcohol in ...
- 483
3
votes
0
answers
64
views
Why does gallium expand on solidification
I've heard that Ga exist as Ga2 molecules in its crystal lattice. Does that have anything to do with expansion of Ga while solidifying? Why and how does it actually expand?
4
votes
0
answers
61
views
Is there experimental evidence to show boiling point increases with external electric field, and if so, by how much?
I was wondering whether anyone has demonstrated that a liquid will have a higher boiling point if it is placed in a very large electric field. I believe to be the case, since induced dipoles would be ...
- 149
-1
votes
2
answers
167
views
When we boil water, does the generated steam remain at the same temperature of boiling point until all water is boiled? [closed]
Suppose we are boiling water in such conditions so that the boiling point of water be $\pu{100 ^\circ C}$.
Does the generated steam have the same temperature of 100 C until all water is boiled?
And ...
- 222
1
vote
0
answers
35
views
How to get Raman shift frequency values from neutron scattering measurements?
I have read some papers that say that a Kohn anomaly mode is a particular feature of 2H- transition metal dichalcogenides and that the existence of such a mode can be seen in neutron scattering data ...
- 65
0
votes
1
answer
936
views
Methanol/water mix freezing point vs specific gravity?
I need to determine the freezing point of the methanol-water mix in the ground loop of my heat pumps. I have a hydrometer and have measured the specific gravity as 0.905. How do I convert this to a ...
- 111
1
vote
1
answer
55
views
More minerals in seawater at greater depths?
There are lists such as the one below detailing how much of different minerals seawater contains:
https://web.stanford.edu/group/Urchin/mineral.html
(For instance )
Would you expect this to be the ...
- 127
0
votes
0
answers
39
views
How to determine whether a reaction is possible by using a phase diagram?
Given the following phase diagram for a binary mixture of $\ce{MoO3}$ and $\ce{Bi2O3}$:
I am asked to determine whether from $\ce{Bi2O3}$ and $\ce{Bi6Mo2O15}$, can $\ce{Bi10Mo3O24}$ and $\ce{...
- 17
2
votes
1
answer
203
views
Formation of AZ91 Magnesium Alloy
I have been researching on how to form AZ91 Common Magnesium Alloy which consists of 90% Mg, 9% Al, 1% Zn, 0.3% Mn. Referring to the article at here, I have read and highlighted important text and ...
- 153
2
votes
1
answer
47
views
Why is the fugacity of a pure component not equal to the pressure calculated by an equation of state for that pure component?
I don't get why fugacity coefficients, $\phi = f/p$, of pure components are usually calculated via integrating an eos over a pressure or volume range. For example, when using a pressure explicit eos (...
- 21
0
votes
1
answer
135
views
Why the density of liquid decreases and density of vapour increases as we approach towards the critical state/point
Pressure and temperature have opposite effects on density. As temperature increases at constant pressure density decreases and as pressure increases at constant temperature the density increases (and ...
- 370
2
votes
0
answers
83
views
Is there a chemical compound which does not have a liquid state but a solid and a gaseous state? [duplicate]
Is there a chemical compound which does not have a liquid state but a solid and a gaseous state? Meaning no matter the temperature or pressure it will never be in its liquid form. According to my ...
- 137
8
votes
1
answer
207
views
Does water expand on freezing more than any other known substance?
Several substances expand on freezing. Gallium expands 3.1% and bismuth 3.3%. However, both of these are much less than water which expands 9%. Is there any substance that expands more than 9% on ...
- 784
-1
votes
2
answers
74
views
Spontaneity criterion for phase transformations and chemical reactions [closed]
Why is the Gibbs free energy (G) considered a spontaneity criterion for phase transformations and chemical reactions? Why are other thermodynamic parameters such as enthalpy (H), entropy (S), and ...
0
votes
3
answers
725
views
Why does equilibrium of ice and water only exist at 273K at normal pressure?
I am a high school student and I am a little confused in the concept of spontaneity of a reaction and how equilibrium works for a reaction, I got some confusions:
Let's take example of freezing of ...
- 242
10
votes
1
answer
819
views
Are molecules exchanged between a solid and liquid in equlibrium?
In Vapor-Liquid Equilibrium, it is my understanding that molecules exchange between the gas and liquid continuously; even when no difference in temperature or partial pressure exists.
Regarding Solid-...
- 471
6
votes
1
answer
256
views
Water getting hotter once frozen?
I packed a fridge with temperature sensors and took over the temperature control in order to have extra cold beer.
One of those sensors is submerged in the middle of a container containing a 4.5% ...
- 171
1
vote
0
answers
195
views
What polyatomic substances have the lowest known freezing points at standard pressure?
At standard pressure, helium never freezes, so that's clearly the coldest liquid—but it's also a monatomic substance.
Diatomic hydrogen freezes at 13 K.
Neon freezes at 24 K.
And then the next coldest ...
-3
votes
1
answer
91
views
Melting and Freezing [closed]
Ok so I needed some help understanding one concept, for eg:- we are in an isolated room that has a room temperature of 0 degrees Celsius. And I bring in some water in the room, so eventually it will ...
- 17
3
votes
2
answers
138
views
Explaining the process of boiling a liquid
I am confused by the thermodynamic definition of boiling. It is stated that boiling occurs when the vapor pressure of a liquid is the same as the ambient atmosphere. Now suppose we deal with an open ...
- 277
2
votes
0
answers
164
views
Interpreting Ternary Phase Diagram Stoichiometry
I am trying to locate the lowest-melting mixture in a system of three nitrate salts: sodium, potassium, and calcium nitrate. I have the relevant ternary phase diagram, but I am unsure exactly about ...
- 792
3
votes
1
answer
391
views
Doesn't the eutectic diagram violate Gibbs's phase rule?
EDIT: As the question hasn't attracted any answers, I tried to put in more detail.
Gibbs's phase rule for a 2 component system at constant pressure says that $F=3-P$, i.e., that the number of degrees ...
- 773
0
votes
0
answers
56
views
Solubility of multiple solutes and limits of solubility during freezing
I'm interested in modeling the freezing of solutions of water and I'm not really sure what happens in water after the solubility of a given material is reached. I know that as ice crystals form they ...
- 217
1
vote
0
answers
79
views
What is the difference between milk and cream that causes disparate result when freezing and thawing?
If you freeze milk and then let it thaw/melt again you just need to shake and it is more or less indistinguishable from unfrozen milk. That is not true for cream - after letting frozen cream (40 % fat)...
- 217
1
vote
2
answers
2k
views
How does water sublimate at normal atmospheric pressures/conditions (i.e., without a phase boundary between solid and gas)?
I remember my high school chemistry teacher stating that water could sublime under normal atmospheric conditions that would exist in e.g., Lancaster County, PA, where Amish would hang clothes to dry ...
- 111
0
votes
1
answer
139
views
Mechanism of successively melting ice with table salt [closed]
Hi I was reading about how regular sodium chloride in itself can melt ice outside, for example ice on roads during low temperatures. However, I am unsure about the exact details, as I have found some ...
- 277
1
vote
0
answers
19
views
Will a liquid-liquid emulsion and the separated emulsion have same volume?
Let's assume that there is no dispersed gas (bubbles). Not sure about dissolved gas; maybe you can tell me if that matters. Ordinary liquids (aqueous solution and biological oil). Surfactants are ...
- 19
4
votes
0
answers
323
views
Is ozone paramagnetic?
This answer shows why ozone should be diamagnetic. Still, Wikipedia article says it is weakly paramagnetic, having positive magnetic susceptibility $χ = \pu{+6.7E−6 cm^3 mol^-1}.$ There's a paper ...
- 1,614
-4
votes
2
answers
70
views
How does part of frozen liquid ( like soup) boil and still be frozen at same time if temperature stays same while melting?
I was reading the following basic question about temperature change during phase change (During phase change in matter, why doesn't the temperature change?), and the answers provided clearly ...
- 763
0
votes
1
answer
343
views
What gas particles are formed when diamond turns to gas?
If you heat up diamond away from oxygen (air completely) until the solid diamond is now gaseous, what are the gas particles made of? Just the element carbon without a charge?
- 748
3
votes
2
answers
305
views
At constant temperature, can the solid phase be more stable than the gas if pressure decreases?
In a phase diagram, the triple point is the point at which the three phases can coexist. If we consider, for example, CO2
If we go below the triple point by decreasing pressure and keeping ...
- 520
0
votes
0
answers
295
views
Does the 1s orbital have two different phases? [duplicate]
How can the 1s orbital (in H atom for example) interfere both constructively and destructively (to give rise to bonding and antibonding molecular orbitals) with another 1s orbital, if the 1s orbital ...
- 31
11
votes
2
answers
184
views
Peak in beer freezing temperature plot
I left an open beer in the freezer while monitoring its temperature. The first minutes works as expected. But after the plateau, at about −8 °C, a peak appeared:
I thought it was an artefact because ...
- 181
1
vote
1
answer
190
views
Why does boiling occur when vapor pressure equals ambient pressure?
Here is my understanding of the boiling process: pressure of the atmosphere is pressing down on the liquid and this pressure is propagated throughout the liquid. That is, pressure everywhere inside ...
0
votes
1
answer
738
views
Boiling of ammonia water [closed]
L̶e̶t̶'̶s̶ ̶m̶a̶k̶e̶ ̶i̶t̶ ̶s̶i̶m̶p̶l̶e̶.̶ ̶I̶ ̶h̶a̶v̶e̶ ̶a̶ ̶p̶o̶o̶l̶ ̶o̶f̶ ̶a̶m̶m̶o̶n̶i̶a̶ ̶w̶a̶t̶e̶r̶,̶ ̶a̶n̶d̶ ̶w̶h̶e̶n̶ ̶I̶ ̶h̶e̶a̶t̶ ̶t̶h̶e̶ ̶a̶m̶m̶o̶n̶i̶a̶ ̶w̶a̶t̶e̶r̶,̶ ̶a̶m̶m̶o̶n̶i̶a̶ ...
- 19
2
votes
1
answer
61
views
Is it possible to have non metallic lithium
I have heard that hydrogen under extremely high pressure and cold temperatures can enter a metallic phase (or just ungodly amounts of pressure and high temperature)
Can the inverse of this be applied ...
- 269
1
vote
1
answer
268
views
Does the vapor pressure of a substance depend on the presence of other gases?
The Clausius-Clapeyron equation (CC equation) can be used to find the (saturated) vapor pressure of a substance ie. the gas pressure at which the two phases (vapor + liquid or vapor + solid) reach ...
- 19
2
votes
0
answers
132
views
Raising melting point of water at STP (using disolved impurities)
Typically, water experiences melting point depression when it is impure. The more impure it is, the lower the melting point, up to a point.
I understand you could raise the melting point by increasing ...
- 157
1
vote
1
answer
340
views
In an open system, can water vapor escape into the atmosphere before reaching the boiling point? [duplicate]
In a closed system, water vapor would have nowhere to go and atmospheric pressure would not be a factor. It would reach dynamic equilibrium with only water vapor.
But in an open system, I think that ...
- 35