Talk:Phase (matter)/Archive 1

This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page.

Archive 1

Headline text

Is the density difference between oil and water really considered a phase difference?

Yes, if you add a third component, for example an alcohol, the alcohol will distribute itself between both phases, such ::that you have a specific phase equilibrium with different compositions in each phase

--Matt Stoker

Perhaps a more exact definition of phase would be helpful. For instance, I had always attributed the oil/water thing to the fact that neither is soluable in the other and that they had a density difference. Is there some special difference between the states of the molecules in different phases?

I think the definition is adequate, the oil and water phases each have unique chemical compositions and physical properties (eg, density, viscosity, etc...). In addition they are separated from each other by a boundary surface. But if you have a better definition or can reword the current definition to make it more clear then go for it! --Matt Stoker

I do think that some ambiguity is built into this terminology, if the paradigm examples given are states of matter such as solid and liquid. A recent edit (as of this writing) includes a comment "Oil and water are the same phase!" Ferrite and austenite are most definitely not the same phase, even when the two have the same composition and even though both are solid. By the way, the specific difference in molecular states is basically one of the polarization of individual molecules & concomitant hydrogen/Van der Waals bonding.--Polyparadigm 18:50, 11 Apr 2005 (UTC)

My professor of chemistry at KULeuven clearly stated that oil and water are in a different phase.--Joris Gillis 19:58, 5 January 2006 (UTC)

Could the person who wrote about polymorphism check the entry on allotropes. I have never heard the term polymorph so I can't tell if they are the same. --rmhermen

It appears that Allotropy and Polymorphism are definitely similar, but the term allotropy is usually reserved for pure elemental solids. From W.D. Callister, Materials Science and Engineering: An Introduction, John Wiley & Sons, Inc. 1991.

Allotropy - The possibility of existence of two or more different crystal structures for a substance (generally an elemental solid) (glossary).

Polymorphism - The ability of a solid material to exist in more than one form or crystal structure (glossary).

Some metals, as well as nonmetals, may have more than one crystal structure, a phenomenon known as polymorphism. When found in elemental solids, the condition is often termed allotropy.(Text on page 38)

--Matt Stoker

This article seems to possibly contradict the one on allotropy -- which says that different physical states (phases) are not allotropes; but here it says the allotropes are different physical states. Is a phase a broader term than allotrope, or what? -- Simon J Kissane

I agree that the wording on these two pages needs to be clarified. First, Allotropy usually refers to forms of pure elements and not other substances, in which case it is called polymorphism. Second, for the case of solids, each allotrope forms a unique phase. This is because each allotrope has distinct physical properties, so a mixture of two allotropes would not have homogenous physical properties, but would consist of distinct regions with properties corresponding either to one form or the other. Therefore, at least for the case of solids, each allotrope is a unique phase. For the case of a gas it gets more confusing. For example, according to the article H and H2 are allotropes. However, in this case since both are in the gas phase, a mixture of the two would constitute a single phase (gases always mix freely to form a single phase).

I think the real distinction is that allotropy refers to differences in the chemical bond structure between the atoms. Physical phase changes from solid to liquid to gas, do not affect the chemical bond structure, so two such phases are not allotropes. However, changes from one solid form (i.e. graphite) to another solid form (i.e. diamond) does change the chemical bonding between atoms, so in this case each form constitutes both an allotrope and a unique phase.

I hope the above discussion makes sense, I will try to incorporate some of the above into the Allotropy page. -- Matt Stoker

The example of H and H2 is not a good one. At thermal equilibrium, the ratio of H to H2 molecules in the gas phase is fixed. H and H2 may be allotropes as part of a thought experiment, but it is not possible do have an arbitrary ratio of H to H2 in the gas phase. That's the meaning of the phase rule. i.e. add some extra H, and it will react to form H2 in the right proportion. Start out with pure H2, and some of it will react to form H. -- User:Olof

The bit about hydrophilic and hydrophobic really had nothing to do with the topic of phases of matter, so I removed it. Am wondering if that example is better off in the Gibbs phase rule page. -- User:Olof

I know what these says because Im familiar with the topic, but something doesn't sound right here:

In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i.e. density, crystal structure, index of refraction, and so forth.)

What exactly do you find objectionable? A phase is a region in the parameter space of thermodynamic coupling constants in which the free energy is analytic. Each point in this parameter space specifies a unique thermodynamic state. Ergo, a phase is a set of states.

Please sign your posts, by the way (use ~~~ to generate a signature.) -- CYD

I find, "A phase is a region in the parameter space of thermodynamic coupling constants in which the free energy is analytic" to be objectionable." The first sentence needs to be much more basic and less technical. Pizza Puzzle

The first sentence in the article is a rephrasing of the proper definition in simple language. In addition to being non-technical, it has the virtue of being correct; your version of the definition was simply wrong. -- CYD

Shouldn't the phase diagram indicate one important difference between water and other substances? For water, the line for solid/liquid transition has negative slope. For most substances, the solid/liquid transition has positive slope.

Shouldn't an article on Phases also define the different transitions condensation, melting, sublimation etc. or at least provide a link to another article which does define the various phase transitions?

"Liquids are distinct from gases because they have much lower compressibility: a gas placed in a large container expands to fill the container, whereas a liquid forms a puddle in the bottom of the container."

The container part is wrong. If I place a gas into an empty container, yes, it will expand to fill it, but if I place liquid water into an empty container, it will also expand to fill it (due to it being empty there is a pressure of 0, and at that pressure water will fill the container). That may not have made a lot of sense, but what I am saying is this: you can't use the container analogy because for the liquid example you are really talking about a mixture of gas (air) and a liquid. Either use a better example or remove this one. Ctachme 04:00, 9 Apr 2004 (UTC)

A liquid placed in an empty container will vaporize, but any liquid component left after vaporization (i.e. partial pressures are equal) will certainly form a puddle. Explaining this might be too confusing in the context of the article, though. -- CYD

Yeah, I just have a pet peeve about not telling the truth to make things simpler (unless of course you say that's what you are doing). I guess it isn't that much of an issue. Ctachme 03:56, 10 Apr 2004 (UTC)

I got to this page because I wanted an intuitive physical understanding of how the phases of matter come about. For example, I had imagined that in solids the molecules (or atoms) were linked together with multiple bonds each, liquids were one-dimensional chains, and gasses were unlinked. Is there anything to that picture as a starting point?

Also, I would like to understand (on a similarly intuitive level) what free energy means. But after chasing down the various references, I haven't been able to build an intuitition for myself. Yet the basis of the explanation here is that it all depends on free energy. So if I don't understand that, I'm lost. -- RussAbbott

The way to visualize it is like this. In a normal solid, the atoms are arranged in a regular lattice. The atoms are very close together, and the bonds between the atoms are very strong, so each atom can only vibrate in position (it isn't allowed to move long distances across the system.) In a liquid, the distance between atoms is about the same as in a solid, but the bonds weaker. Therefore, the atoms can slide past one another (like the grains of sand in an hourglass.) That's why liquids can flow, while solids are more or less rigid. A gas is basically the same as a liquid, but the atoms are much farther apart from each other.

Thanks CYD. If a solid and liquid have the same atoms/molecules the same distances away from each other and the same bonds, why are the bonds weaker in a liquid? In what sense are the bonds weaker? What makes them weaker? I would have thought that a bond was a bond. I'm also surprised to hear that the bonds are the same in all three states!

Assume that I understand high school chemistry and know what bonds are--although I do have questions about that also. But that's a different page.

I realize that it's hard to get the right level of explanation for everyone.

I'll see if I can flesh out this picture and use it as an example in the article.

And yes, the free energy article is somewhat lacking. I'll see if I can fix that, too. -- CYD

I'll be looking forward to it. -- RussAbbott

Please check related article

Could someone with more expertise in physics please check the related article List of phases? I may have errors in the times after the big bang when symmetry broke and the forces separated (and the description of this state may be wrong). Also, my first description of supersolid may be wrong, I'm not sure I understand how that state differs from that of a superfluid. RJFJR 23:44, Jan 16, 2005 (UTC)

simple explanation?

Perhaps in the introduction section, or before the technical definition of phase, could put a simplistic explanation of phase as it is usually given in K-12. That is, one sentence each for solid, liquid, and gas. I think a number of people coming to this page (including myself--I am a teacher) are looking for that information rather than the highly technical physical chemistry definition that is on this page. I wouldn't be looking for a lot of detail, that could be found on the relevant pages, just acknowledgement of the "standard" phases. ("Standard" meaning those we experience in every day life.) Alternately, I would be satisfied with a more prominent link to list of phases along with an indication there as to which are the "standard" ones. --zandperl 00:33, 2 Feb 2005 (UTC)

It's not exactly accurate to describe the solid/liquid/gas phases as "standard" phases. As explained in the article, the question of what a phase is depends on what physical variables you are looking at. If you look at pressure or volume, you encounter solid, liquid, and gas phases, and more "exotic" phases like Bose-Einstein condensates. If you look at magnetization, you encounter ferromagnetic, diagmagnetic, and paramagnetic phases. From this point of view, ferromagnetism is by no less "standard" than solidity.

In any case, the introduction already provides a succinct definition of a phase: "a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i.e. density, crystal structure, index of refraction, and so forth.) The most familiar examples of phases are solids, liquids, and gases." If you have any better suggestions, feel free to implement them. -- CYD

I agree with zandperl, this article is far too technical for the lay reader. As a physics graduate I can understand the terms, but it reads more like an advanced textbook than an encyclopedia entry. The information is clearly useful and interesting, but surely the article can start with a simpler introduction? Perhaps to compromise we could have the more basic information at 'States of Matter', with a link to this page at the top? I discovered this page while creating a link to 'condense' and found nothing of use to the average reader! --cfg 18:26, 22 Jun 2005 (UTC)

Phase equilibrium

There's a little article on phase equilibrium that can take up some of the technical details and more advanced concepts from here...in fact, it could use a lot of expansion, IMO.--Polyparadigm 19:42, 10 Mar 2005 (UTC)

There's no need to remove anything from this page; the four paragraphs on phase separation that we have is not a lot. -- CYD

Definition of a solid seems to include liquids as well...

We know, for example, that the property that defines a solid -- resistance to deformation -- is exhibited by materials as diverse as iron, ice, and Silly Putty. The only differences are matters of scale. Iron may resist deformation more strongly than Silly Putty, but both maintain their shape if the applied forces are not too strong.

I'm just playing devil's advocate here, mostly in an effort to understand/improve the definition of a solid. Here's my concern:

Water, like ice, also in some sense, "resists deformation"; for example, I can float a needle on it, and insects can walk across it. The only difference is a matter of scale; ice can resist more deformation than water can. But water our word for the liquid form of ice...

Water and ice both maintain their shape if the applied forces are "not too strong", where "not too strong" is admittedly very weak.

Can someone think of a more carefully worded definition of a solid that doesn't include water?

What you say is absolutely correct. I think it's at a tangent with what the article is talking about at that point, but I could be wrong and it could be relevant (I need to think more about this.) Off the top of my head, though, at some sufficiently short length scale there won't be any difference between a solid and a liquid -- both are made of atoms, and phase phenomena only arise in the thermodynamic limit. So I think the effect of surface tension (which is what you're referring to) is not relevant to distinguishing a solid from a liquid; what really matters is the behavior in the bulk.

In any case, a more precise definition of a fluid is something that doesn't behave elastically in response to shear. A fluid can support compressional (longitudinal) waves (a.k.a. sound), but not transverse waves; a solid supports both longitudinal and transverse waves. A fluid can put up a certain amount of resistance to a shear force -- i.e., viscosity -- but this resistance doesn't give rise to transverse oscillating modes (transverse waves) that propagate out to large distances. Again, this is referring to the behavior in the bulk, so surface waves don't really count here. I'm not sure how (or if) the article needs to be clarified on this point, though... -- CYD

Example

I think that a water ballon is not a good example of the 'incompressibility' of water. Water balloons squish around in your hand and it is hard to tell whether the volume has changed. ike9898 13:33, 27 November 2005 (UTC)

When I think about it, I imagine a "corked" pump (such as one used to fill a bicycle tire or even a hyperdermic needle) filled with water as opposed to air. I even think a plastic zip-top bag filled with water is a better example than the balloon, but I can understand how a water balloon can create better imagery. The_Irrelevant_One 19:03, 12 March 2006 (UTC)

Photos?

Can we think of a good photo to add to the top of the article? (It's just for appearance). RJFJR 15:47, 6 October 2006 (UTC)

Following the request of PhotoCatBot to check if a photo is still needed, I have now added a nice photo of an argon crystal simultaneously melting and evaporating. Dirac66 (talk) 00:24, 14 April 2009 (UTC)

Today 203.110.243.21 added the note "at 273K temperature" to the caption of this photo. However from the descriptions of this photo by the photographer (User:Deglr6328) at File:Argon ice 1.jpg#Summary and at greater length at Wikipedia:Featured picture candidates/Argon ice, it is clear that the temperature was not controlled or measured while the photo was taken. The sample was in the process of warming rapidly from liquid nitrogen temperature (77 K), and no specific value of the temperature at the moment of the photo is claimed. So I will now delete the note about the temperature. Dirac66 (talk) 03:29, 12 November 2012 (UTC)

The melting argon ice photo is striking, but a bit hard to understand, which might be fixed by a more thorough explanation in the caption, or a different picture. I couldn't see any solid-liquid interface in the picture, so at first I thought there was only liquid argon, wetting the inside of the glass tube and dripping out, and then evaporating. The presence of both liquid and vapor is evident, due to the falling liquid drops and the fog formed when the cold, transparent argon gas phase mixes with the surrounding humid air, but unfortunately the fog isn't itself a phase, but rather a two-phase region. This could all be explained, but maybe a cleaner approach to showing three coexisting phases would be a picture of a lump of solid bromine, melting to form a puddle of liquid bromine, with a visible cloud of red bromine gas above. The bromine article has a nice picture of a bottle of bromine showing coexisting liquid and gaseous phases, so anyone who has such a bottle shouldn't have much trouble making one with all 3 phases showing. Put the bottle on a slant in a freezer at -10C, then take it out and let the frozen bromine partly melt, meanwhile forming some bromine gas. The liquid and solid bromine would be both opaque brown but could be distinguished by the solid part still being on a slant while the liquid part was level.CharlesHBennett (talk) 14:02, 3 May 2013 (UTC)

In the argon photo, I think the white streaks near the centre of the test tube are the solid, and the clear areas surrounding are the liquid. Dirac66 (talk) 18:52, 6 May 2013 (UTC)

Bose-Einstein concentrate

shouldent it be added, it is a distinct type of matter

Bose-Einstein condensate is already there, with a link to its own page.

other "type"s?

Tabascofernandez (talk) 02:51, 9 August 2017 (UTC)

Added "copypaste" template

I'm surprised this article earned a B-class assessment. Several sections use the first person and tone that strongly resembles a science textbook, leading me to believe the text has been copied from some (uncited) educational material. Some examples:

Under General definition of phases: "When discussing the solid, liquid, and gaseous phases, we talked about rigidity and compressibility, and the effects..." and "On the other hand, when discussing paramagnetism and ferromagnetism, we looked at..." What previous discussion can these refer to, other than preceding chapters of a larger work?
Under Other examples of phases: "In this section, we will present several systems that exhibit phase phenomena" is entirely unnecessary and resembles the preamble to a textbook section or subsection.
The word "we" appears at least 11 times.

I have declined to do the extensive editing required to transform this textbook chapter into proper Wikipedia article. If the source can be identified and is in the public domain, then such editing can take place; otherwise the article should be substantially rewritten. The current text is unacceptable for an article identified as a 1.0 Core Topic. -- PaulKishimoto 20:04, 2 January 2007 (UTC)

I've identified the origin: http://en.wikipedia.org/w/index.php?title=Phase_%28matter%29&diff=18722376&oldid=18528013 68.39.174.238 05:31, 4 January 2007 (UTC)

- The text is here also but if that is the original it was already pasted into this article in 2003:

http://www.math.unimaas.nl/personal/ronaldw/Emerging%20Complexity%20Syllabus.pdf

The last version before the paste:

http://en.wikipedia.org/w/index.php?title=Phase_%28matter%29&oldid=1007559

I suggest that we trim down the article with respect to the pasted-in material and then reevaluate the 2003 material

V8rik 17:20, 12 January 2007 (UTC)

Hmm, it looks like even that image has a questionable copyright, as it was created from an image which was recreated due to a copyright problem. As to the text, I'm going to remove all of it that seems to be in violation. The original adder is evidently no longer active here. 68.39.174.238 11:55, 10 February 2007 (UTC)

I have made my edits here and welcome other review of them. I suspect the last two are rewritten from the original copyright problem, but not completely free of taint, both of copyright violation and of the original out-of-place feel of the source. 68.39.174.238 12:05, 10 February 2007 (UTC)

Temperature distribution of phases of the elements

Do you have any use for this chart? --81.27.125.127 (talk) 21:25, 29 April 2008 (UTC)

General question about phases of matter

Is it possible for a metal to become gaseous? I was hoping to find a definitive answer here, but this page seems to be much more technical than I was expecting. —Preceding unsigned comment added by Gforce20 (talk • contribs) 21:34, 9 October 2008 (UTC)

Definitely yes. If any metal is heated to a high enough temperature, it will first melt to become a liquid, and then boil to become a gas. For example, copper has a melting point of 1085“C and a boiling point of 2562°C , so it is a gas at temperatures above 2562°C (at atmospheric pressure). Dirac66 (talk) 22:56, 9 October 2008 (UTC)

State Of Matter

Why does State Of Matter redirect here instead of to State of matter? I'd change it, but maybe there's a reason I don't know about? -- Cowplopmorris^Talk_Contribs 12:16, 5 October 2011 (UTC)

That redirect dated from 2004, when there was no State of matter article. I have now fixed the redirect. Dirac66 (talk) 18:00, 5 October 2011 (UTC)

Phase transitions

I want to know the State, Matter, Heat/Cool. Process, Changes, State of Solid Liquid Gases —Preceding unsigned comment added by 219.64.129.203 (talk) 15:55, 17 July 2009 (UTC)

The nomenclature for the various phase transitions is given in the article State of matter. Dirac66 (talk) 16:27, 17 July 2009 (UTC)

if water will notfunction as the solvent

what to yse if water will work as a solvent on a hydrophobic substance likeink —Preceding unsigned comment added by 24.46.151.213 (talk) 00:52, 21 January 2009 (UTC)

my VIEW (not?)

there is three (+1) phases: solid (s), liquid (l), and vapid (v) [+ plasmid (p)].
s --> l : liquidation (reversed: DE-liquidation)
l --> v : vapidation (rev: DE-vap)
v --> s : solidation (rev: DE-sol)
LNG: natural devapidatives ; NDV
Tabascofernandez (talk) 02:49, 9 August 2017 (UTC)