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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7
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2answers
656 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 ...
2
votes
1answer
111 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 ...
2
votes
1answer
73 views

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

a) No effect b) The melting point increases when the air pressure increases c) The melting point decreases When the air pressure increases The boiling point has inverse relation with ...
6
votes
1answer
49 views

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

a) Increase the melting point b) Decrease the melting point c) No effect on melting point It was a question in the test I passed today. I know adding impurity decreases the melting point of a ...
7
votes
0answers
32 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 ...
5
votes
2answers
104 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?
4
votes
1answer
112 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), ...
1
vote
0answers
13 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 ...
13
votes
1answer
2k 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 ...
4
votes
0answers
64 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 ...
1
vote
0answers
48 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 molecules. Take for example, molecular compounds that have a very low molar mass like ...
-4
votes
2answers
47 views

Can gas get produced at room temperature? [closed]

Is there any reaction between solid/ liquid elements/compounds at room temperature that produces gases??
0
votes
1answer
72 views

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

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 ...
11
votes
1answer
129 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
votes
3answers
88 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
votes
1answer
24 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?
6
votes
1answer
32 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
votes
1answer
122 views

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

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 ...
3
votes
2answers
244 views

Can water be liquefied or solidified just by adjusting the temperature, regardless of the pressure?

technically the line between liquid and solid phase would go a long way before hitting the y-axis, but the point is it will eventually. So the question remains, can any liquids, including water ...
10
votes
1answer
498 views

Why can't helium be solidified at 'ordinary' pressures?

According to the UC Davis ChemWiki Chemistry of Helium, helium has a comparatively unusual property, specifically: Helium is the only element that cannot be solidified by lowering the temperature ...
3
votes
1answer
45 views

Why the dilution of solvent doesn't affect the solid phase, in comparison to the liquid phase?

Dilution of the solvent adds new energy states to the liquid, but does not affect the solid phase. The above line appeared on the following page under the section "5: Colligative properties and ...
2
votes
1answer
32 views

50-90'C color changing chemical to use as warning marker for hot electronics?

I am testing electronics with many potentially unstable contacts, and I wish to monitor if they rise above 50 to 90 degrees Celsius, i.e. using carbon paper that would darken progressively from 50 to ...
2
votes
1answer
81 views

Endothermic Conversion of Liquid to Gas

When a liquid (in my case I used butane) under high pressure is released into the air, it becomes gaseous, and the container seems to get colder. Why is it that turning a liquid to a gas requires ...
-2
votes
1answer
88 views

Interpreting a Phase Diagram?

The correct answer (that is false) is A) however can someone please explain why the other options would be true and why it is in fact possible to compress a solid to produce a liquid?
1
vote
1answer
25 views

Bonding and Phase Changes?

When water boils into water vapor, its temperature (average kinetic energy) does not change because the inputed energy is used to break its bonds. But how does that work? Also, in a liquid, aren’t ...
4
votes
1answer
72 views

Having trouble understanding the iron-carbon phase diagram

At room temperature, alpha and alpha+$\ce{Fe3C}$ are present (depending on carbon content), which is ferrite and pearlite. In the lab we polished and etched samples of carbon steel to observe the ...
4
votes
1answer
51 views

How many critical points? Why?

Critical points are defined (by wikipedia) as the "end-point of the phase equilibrium curve". I would say this diagram therefore has three critical points. But this is unnatural. I doubt its true. ...
0
votes
1answer
78 views

How much water evaporates In a vacuum before freezing?

I placed a container with 1000 grams (1 kg) of water at room temperature (20 degrees celsius) Inside a vacuum at 0.03 atm pressure. The water boiled for a few seconds then froze solid. I need to ...
0
votes
0answers
36 views

Meaning of equilibrium in “Vapour in equilibrium with liquid”?

In my physical chemistry book it says "Consider a liquid sample of a pure substance in a closed vessel. The pressure of a vapour in equilibrium with the liquid is called the vapour pressure of ...
2
votes
1answer
118 views

What are the triple point pressure and temperature for pure cyclohexane?

Here is a video that demonstrates the interesting nature of the triple point of cyclohexane, so I tried researching on the internet for a phase diagram, but only found data from a manufacture where ...
2
votes
1answer
30 views

compression set of tin catalyzed silicone better than platinum?

Platinum silicone is more dimensionaly stable, it shrinks less when it cures. However, i just need silicone which has good compression set (small change by compression), and perhaps, once they are ...
3
votes
2answers
61 views

Structures present in liquid water

I know this may be a too generic question, but here it goes anyway. It is already know that solid water (ice) organizes its molecules in a lattice (in a variety of 16 different crystals and one ...
4
votes
2answers
322 views

Why does water change phase so easily?

I did some undergraduate level Chemistry as part of my degree. It left me with the distinct impression that the polarity of water is responsible for its unusual phase properties: it's the only ...
38
votes
7answers
11k views

Is toothpaste solid or liquid?

My teacher didn't answer this properly: Is toothpaste solid or liquid? You can't say toothpaste is a solid because solid material have a fixed shape but toothpaste doesn't. However, you can say ...
1
vote
2answers
37 views

What's sulphur's state of aggregation in petroleum?

Using google, I wasn't able to find an answer to this question. Conditions: p = 1 bar and T = 298 K.
-9
votes
1answer
98 views

Why does the freezing point of a sample gas occur at a certain temperature? [closed]

From "North Carolina Measures of Student Learning: NC’s Common Exams Chemistry" (Source, Number 20): The graph below shows a cooling curve for a sample of gas that is uniformly cooled from ...
6
votes
1answer
124 views

How to find and use the Clausius-Clapeyron equation

I know how to get the equation from the Clapeyron equation but I have a question regarding a the integration along a phase boundary and a small step in the derivation that I will make clear when I ...
2
votes
1answer
112 views

Does the density of a liquid and gas phase of a substance(nitrogen or water) converge when reaching critical point

I know that the there is no difference in density in a liquid and a gas phase of a substance after the critical point. But I do want to know if this difference in density is more continuous or if it ...
2
votes
1answer
86 views

Phase rule and degrees of freedom

In the formation of 3-bromo-1-butene and 1-bromo-1-butene, from $\ce{HBr}$ and $\ce{C_4H_6}$, in a gas phase: $\ce{HBr + C_4H_6 \to 1BrC_4H_7}$ $\ce{HBr + C_4H_6 \to 3BrC_4H_7}$ the number of ...
4
votes
1answer
72 views

Phase diagrams (weird region)

On the left, there is a region for $\ce{MgO(ss)}$. I've been told such regions exist because stuff are not miscible. However, does that mean the composition axis on the bottom is a lie? Namely, ...
0
votes
2answers
257 views

What is the specific heat of copper through its phases?

Specific heat is the amount of heat required to change the temperature of 1 gram of a substance by 1 Celsius. For instance, the specific heat of water in the solid phase is 2.059 J/gC and 4.184 J/gC ...
0
votes
0answers
23 views

How can a melting and a freezing point of ice be the same [duplicate]

How can a freezing and a melting point of ice be the same ??
2
votes
3answers
1k views

Since the formation of diamond from Graphite is endothermic and the entropy decreases for this process, how is it possible to make diamond?

Surely G would always be positive and thus would make it impossible to make diamond. Clearly this is not the case. But how? Would an increase or decrease in temperature aid it's formation? I think a ...
2
votes
1answer
51 views

Are there attempts to investigate phase states at negative pressure?

Phase diagrams of various compounds and systems usually include only positive pressure. But I wonder whether it is possible to somehow investigate them under negative pressure? Are there materials ...
3
votes
1answer
142 views

Boundary lines in phase diagrams and the lever rule

My first question is: What exactly happens on a point situated on a line? Or on a point such as E in this figure? Does point E mean that the $\delta , \gamma + \delta , \delta + \epsilon , \gamma + ...
6
votes
1answer
873 views

Does everything exist as a gas at P = 0?

Attached is a phase diagram for carbon dioxide. At P = 0, it appears that the substance will exist as a gas regardless of temperature. My questions are: For any liquid at a fixed temperature, is ...
15
votes
2answers
766 views

How many molecules does it take to have a phase?

A single molecule can't be solid, liquid or gas. It's just a molecule. A mole of something can be any of the three. So, how many molecules does it take for phases to be meaningful? I realize that ...
1
vote
2answers
103 views

What happens when ice melts?

What happens when ice melts? I have this question, with two possible answers: regularly arranged molecules change into irregularly arranged molecules water molecules become less densely packed ...
6
votes
4answers
6k views

During a phase change in matter, why doesn't the temperature change?

I was working on something in school and came across the question: "Why do you think the temperature does not change much during a phase change?" I'm really not sure why this happens in matter ...
0
votes
2answers
362 views

How to figure out which phase in The Phase Diagram will have more density?

If I am given Phase Diagram and asked to determine which phase will have more density? What to consider to solve this kind of questions is it about thr area that each phase occupies? the more area a ...