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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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2answers
645 views

Why does water condense on grass and iron grills in cold weather?

In my book it is said that in cold weather fog appears. This fog is nothing but water droplets. After a hot day if the night is cold then the moister in air starts to condense. What I do not ...
5
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0answers
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 ...
2
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2answers
5k views

Why is carbon dioxide gas used in soda?

Why is carbon dioxide used in soda? What makes it preferable to other gases for this purpose?
5
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2answers
165 views

Phase subscript for supercritical reagent?

When writing a chemical reaction, one can use subscripts to denote the phase of a reagent, e.g. $\ce{SiO2 (s)}$, $\ce{H2O (l)}$, $\ce{F2 (g)}$ or $\ce{Na^+ (aq)}$. However, I need to write a reaction ...
2
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2answers
161 views

Why don't substances have a condensation point?

All substances have a freezing point at which they transition from a liquid to a solid. They all also have a melting point at which they transition from a solid to a liquid. However, as far as I can ...
4
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1answer
45 views

Kinetics of air evolving from water on heating

Is there a simple relationship describing the kinetics of air evolving from water on heating? For example, if I let water at room temperature and pressure saturate with air, it should have some ...
1
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0answers
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 ...
1
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0answers
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 ...
3
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0answers
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 ...
13
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5answers
23k views

Difference between state of matter and phase

What is the difference between state of matter and phase? This site said that: Phases are different from states of matter. The states of matter (e.g., liquid, solid, gas) are phases, but matter ...
1
vote
1answer
398 views

What equipment to use to make liquid oxygen?

I'd like to do some experiments with liquid oxygen but as a first step I'll have to make some. Unfortunately I don't have any experience designing cryogenic experiments. I'm thinking I'll cool gaseous ...
0
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0answers
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 ...
0
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1answer
85 views

Can you call a table frozen? [closed]

Someone has argued that the table sitting in front of us is 'frozen'. I do agree that the table has a freezing point. The table has a melting point, but that is beyond the ignition point and the ...
13
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2answers
5k views

Burns from boiling water and steam

Why is a burn to the skin caused by steam more serious than a burn caused by the same amount of boiling water at the same temperature? The temperature is the same, which implies that the kinetic ...
0
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2answers
11k views

Sublimation of Iodine

Why does iodine sublime? I have researched it myself and I have got the same answer; it sublimes because it directly converts from solid to gas. But why don't bromine or chlorine also sublime?
0
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0answers
106 views

Ice under very high pressure phase transitions [duplicate]

If you put a piece of ice into a very high pressure chamber and increase the pressure, I can understand how the ice turns to a water state. But what happens after that? Does the pressure push the ...
10
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1answer
2k views

Why must both the critical temperature and pressure be exceeded to achieve the supercritical phase?

The characteristics and properties of supercritical fluids and the associated vapor-liquid critical point are well established. One thing that I've always been curious about, though: what is the ...
2
votes
2answers
535 views

What is the state of the oxygen free radical in the following reaction?

$$\ce{O2(g) ->[h\nu][\nu\,<\,240~nm]2O^{.}(?)}$$ Oxygen is split by UV light below 240 nm to form oxygen radicals, which then go on to react with oxygen molecules to form ozone. Firstly, is ...
3
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1answer
141 views

How long does it take to change states of matter?

I'm interested to know how long it takes to change states of matter and why it takes the time that it does. For example, what is the very quickest that we could freeze a packet of chicken breasts? ...
29
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2answers
5k views

What happens if you cool water in a container too small for it to freeze?

Freezing a full bottle of water tends to shatter the glass bottle. What if you used something tougher than glass, like diamond? What would happen if you kept dropping the temperature, but restrained ...
1
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1answer
2k views

Properties of plasmas

In chemistry one can recognize that the four states of matter are solid, liquid, gas and plasma. The first is rigid, and has a definite shape and volume. The second doesn't have a shape, and assumes ...
2
votes
2answers
618 views

Making Liquid CO2

I recently saw a video on making liquid $\ce{CO2}$: https://www.youtube.com/watch?v=8AN_XMcD3yI Basically we seal some dry ice in a container. As the dry ice sublimates the pressure inside the ...
0
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0answers
47 views

What phase of matter is salt when dissolved in water? [duplicate]

Being an ionic solid, salt is very susceptible to being torn apart by the polar molecules of water. Inside the water, salt exists as sodium and chlorine anions; but what state of matter is it in? My ...
2
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0answers
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 ...
5
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2answers
518 views

Contact explosion of nitrogen triiodide

Nitrogen triiodide, on slightest physical contact, explodes to evolve dense purple fumes of iodine. Why does this phenomenon occur? video link - https://www.youtube.com/watch?v=2KlAf936E90
9
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3answers
792 views

Is there a gas with metallic luster?

We know that both solids and liquids can exhibit metallic luster. I wonder whether there is a gas that when filling a transparent envelope (such as a glass tube) would make it appear with metallic ...
5
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2answers
1k views

Why does sodium polyacrylate solidify, on addition of water?

Sodium polyacrylate is a white powder with a characteristic odor. But when we add water to this powder, instead of forming an aqueous solution, it instantaneously solidifies and forms more amount of ...
13
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2answers
3k views

What color is solid methane?

Is it blueish, perfect white or some other color? I am interested because some celestial bodies are said to be covered with methane ice.
7
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1answer
5k views

Why does color of halogen deepens and the boiling point decreases down the group?

Why does the color of the halogens deepens as we go down the group? also why there is a change in physical state of halogens down the group? \begin{array}{c|c} \mathbf{Gas} & \mathbf{Color} \\\...
7
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2answers
1k views

Is dew and water vapour the same?

Is it possible to say water vapour and dew is the same? I know that the water vapour is the gaseous phase of water. But what is the dew? I just wonder how can I categorised it. Is it the liquid or ...
4
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1answer
2k views

What is the difference between an amorphous solid and glass?

They are both formed when a liquid is supercooled rapidly, no free energy, and they both have irregular structures. What defines a glass other than how it is amorphous, transparent, and has a glass ...
4
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2answers
27k views

The effect of air pressure on the “melting point”?

What is the effect of air pressure on the melting point of a substance? a) No effect b) The melting point increases when the air pressure increases c) The melting point decreases When the ...
7
votes
1answer
484 views

At the eutectic point, what is the effect on the melting point of adding impurities?

At the eutectic point, what is the effect on the melting point of adding impurities? Increase the melting point Decrease the melting point No effect on melting point I know adding ...
9
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1answer
110 views

Which elements tend to form the most phases?

Some combinations of two elements have very complicated binary phase diagrams across the weight% horizontal axis. Others are rather simple. Is this a function of only one or both of the elements ...
6
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2answers
603 views

Super-cooled liquids

I understand that it is possible to cool a liquid past its freezing point, and still maintain its liquid state because crystallisation would not happen in the absence of a seed crystal. My question, ...
5
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2answers
307 views

Can all substances be supercooled?

With optimal conditions can we supercool any compound or is it that just water and a certain set of others can be supercooled? If not, why?
5
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1answer
3k views

At what temperature CO2 becomes solid at normal pressure? [closed]

I have met contradicting evidence. The phase diagrams show that $\ce{CO2}$ solidifies at $-78.5\ ^{\circ} \mathrm{C}$: Wikipedia confirms this At 1 atmosphere (near mean sea level pressure), the ...
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0answers
40 views

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 ...
17
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1answer
8k views

Molten vs Liquid

When I start studying electrochemistry,I learn the words molten and aqueous. I don't have a problem for aqueous but I'm a little bit confuse about molten. For me, molten means melt, which means ...
20
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6answers
2k views

Why does HCN boil at a higher temperature than NH3?

The boiling point of ammonia is −33 °C while that of $\ce{HCN}$ is 25 °C. In a recent AP (Advanced Placement) Chemistry test, a free response question asked why this is the case. Can someone shine ...
7
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0answers
330 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 ...
4
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1answer
7k views

How to determine if a compound is likely to become a solid at room temperature?

Reasoning: My guess would have to be that it has to do with the strength of the intermolecular forces between each molecule. For example, molecular compounds that have a very low molar mass like $\ce{...
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2answers
247 views

Can gas get produced at room temperature? [closed]

Is there any reaction between solid/ liquid elements/compounds at room temperature that produces gases??
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1answer
281 views

Out of the various states of matter, which one is the most used? [closed]

Apart from the what everyone knows about, solids, liquids, gasses, plasma, BEC. What are the other states of matter and what are they used for? I would like an explanation as well as an example of ...
12
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1answer
394 views

Jahn-Teller Metal : The new state of matter

Recently it came in the news that scientists have discovered a new state of matter called Jahn-Teller metal. I tried reading up on it but couldn't understand it clearly. Please explain in simple ...
4
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3answers
1k views

Liquid-Liquid phase separation

Consider a container that contains a mixture of many liquids. Can two of these liquids phase separate without having any significant effect on other liquids inside the container? Is there a feasible ...
0
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1answer
35 views

Determining phase from intermolecular interactions and kinetic energy

If the energy of intermolecular attractions are much less than the average kinetic energy of the molecules, what is the physical state of the substance?
7
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1answer
3k views

change in state (sublimation and deposition)

I am slightly confused as to how I should think of changes in state (especially sublimation and deposition). Should I think of sublimation and deposition as skipping the liquid phase (fig 1) or should ...
8
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1answer
917 views

Open Database of Phase Diagrams?

Is there some kind of database that has information about phase diagrams of different substances? I'm mostly looking for phase diagrams of elements (silicon, iron, hydrogen, etc.) because I'm trying ...
2
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1answer
8k views

What elements and/or substances without water are liquid at room temperature? [closed]

I was thinking about liquids, and I started to wonder theses related questions: 1) Besides mercury, what elements are naturally liquid at room temperature? 2) What naturally found family of ...