Talk:Liquid

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WikiProject Chemistry (Rated B-class, Top-importance)
WikiProject icon This article is within the scope of WikiProject Chemistry, a collaborative effort to improve the coverage of chemistry on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
B-Class article B  This article has been rated as B-Class on the project's quality scale.
 Top  This article has been rated as Top-importance on the project's importance scale.
 
edit·history·watch·refresh Stock post message.svg To-do list for Liquid:

Here are some tasks awaiting attention:
  • Article requests : **Diagrams:
      • A diagram of how the configuration of molecules/atoms differs for the solid, liquid, and gas phases. See Elastic collision for an animated (!) example.
      • A similar diagram could show how evaporation and freezing work (or could be added to those articles).
      • A diagram showing how pressure changes with depth would be enlightening.
      • Expand : ** An explanation of what makes a fluid and a liquid different would be helpful.
      • An "examples" section would be quite educational for basic readers.
      • An "applications" section would be interesting, mentioning things like solvents, coolants, and lubricants.

Introduction section[edit]

Hi everybody. I'm back from my holiday vacation, and see that there has been a little progress made, and quite a bit of drama played out. As promised, I have gone through Logger9's version to see if we could salvage anything to be used for an intro section, which this article is currently lacking. I have extensively reviewed the material, line by line, hoping to help Logger9 improve his own contributions, and have rewritten it as follows:

Liquid is one of the three principal states of matter, with the others being solid and gas. A liquid is a fluid. Unlike a solid, the atoms in a liquid have a much greater freedom to move. The forces that bind the atoms together in a solid are only temporary in a liquid, allowing a liquid to flow while a solid remains rigid.

The atoms and molecules in both a liquid and a solid are spaced fairly close together, and so exhibit similar densities. The solid state of matter is different from liquid because the atoms are usually locked into very specific arrangements, forming crystals. Solids resist changes in shape, called deformation, and, therefore, display the property of rigidity. In contrast, the atoms in a liquid have much more freedom to move around, which allows them to easily rearrange themselves on microscopic scales, which becomes flow on larger scales. Since the atoms in solids and liquids are closely spaced, the branch of physics that deals with both is called condensed matter physics.

Liquid particles are bound firmly but not rigidly. They are able to move around one another freely, resulting in a limited degree of particle mobility. This freedom for the atoms to move results from the temperature of the material. Heat is the vibrational motion of the atoms, so as temperature increases the vibration causes distances between the atoms to increase. When a liquid reaches its boiling point, the cohesive forces that bind the atoms closely together break, and the liquid changes to its gaseous state. If the temperature is decreased, the distances between the atoms become smaller. When the liquid reaches its freezing point the atoms will usually lock into a very specific order, called crystalizing, and the bonds between them become more rigid, changing the liquid into its solid state.

I know this is not complete, and some of my understanding may be incorrect, but I believe it would be a good starting point for an introduction section. If anyone feels up to improving upon it, I believe it would be beneficial to have an intro section here. Zaereth (talk) 00:50, 1 December 2009 (UTC)

It is better. Get rid of atoms everywhere, though, it is molecules that matters. The 2nd paragraph is mostly wrong, so kill it. I think what we have under phase transition in the article is much better. And I think that we are missing the bit about how liquids reacts to a container compared to a gas and to a solid is an important, but missing bit from the introduction. I'd also at least mention that liquids only are stable under pressure, as I find that to be a very defining bit for liquids. All in all, very good work work! Esben (talk) 09:59, 4 December 2009 (UTC)
Thanks! As you can probably tell, I'm straying a bit out of my expertize when I'm not discussing stuff like laser pumping or basic fighter maneuvers. My knowledge of liquid is mainly limited to its application in hydraulics, so can I ask you to make the appropriate changes? The intro should really bridge the lede with the rest of the article, and should briefly touch on every section to follow. Zaereth (talk) 20:21, 4 December 2009 (UTC)
Ok, I'll take another crack at this. There are a few things which I don't understand. I know from dealing with vacuum pumps that the boiling point of certain liquids lowers with pressure. (The boiling point for water, in space, I've read is -90 degrees F.) I don't know if this is true or not for other liquids, such as mercury or vacuum pump oil. I have made the changes recommended by Esben, and have tried to construct an intro paragraph, a paragraph about properties, and a paragraph about phase transition. It may need a little more work, and could use a paragraph about structure, (fron someone who understands it better than I), but I think this could work for an intro section. Does anyone else have something to add? Zaereth (talk) 21:00, 11 December 2009 (UTC)
Liquid is one of the three principal states of matter, with the others being solid and gas. A liquid is a fluid. Unlike a solid, the molecules in a liquid have a much greater freedom to move. The forces that bind the molecules together in a solid are only temporary in a liquid, allowing a liquid to flow while a solid remains rigid.
A liquid, like a gas, displays the properties of a fluid. A liquid can flow, assume the shape of a container, and, if placed in a sealed container, will distribute applied pressure evenly to every surface in the container. Unlike a gas, a liquid may not always mix readily with another liquid, will now always fill every space in the container, forming it's own surface, (except in a vacuum), and will not compress, (except under extremely high pressures). These properties make a liquid suitable for applications such as hydraulics.
Liquid particles are bound firmly but not rigidly. They are able to move around one another freely, resulting in a limited degree of particle mobility. This freedom for the molecules to move results from the temperature of the material. Heat is the vibrational motion of the molecules, so as temperature increases the vibration causes distances between the molecules to increase. When a liquid reaches its boiling point, the cohesive forces that bind the molecules closely together break, and the liquid changes to its gaseous state {unless [superheateding] occurs}. If the temperature is decreased, the distances between the molecules become smaller. When the liquid reaches its freezing point the molecules will usually lock into a very specific order, called crystalizing, and the bonds between them become more rigid, changing the liquid into its solid state.
Sorry for not responding, real life got in the way. I think the above is excellent; only two small matters: Vacuum and liquid don't mix (place liquid in a vacuum and some of the liquid will vapourize, filling the vacuum). So I would remove that parenthesis. The other thing is superheating and supercooling. I would fix that by adding the parenthesis. Finally finally or think the sentence with "Heat is vibrational motion of the molecules" is both slightly wrong and unnecessary, so I would condense it. Thus, I arrive at
A liquid, like a gas, displays the properties of a fluid. A liquid can flow, assume the shape of a container, and, if placed in a sealed container, will distribute applied pressure evenly to every surface in the container. Unlike a gas, a liquid may not always mix readily with another liquid, will now always fill every space in the container, forming it's own surface, and will not compress, (except under extremely high pressures). These properties make a liquid suitable for applications such as hydraulics.
Liquid particles are bound firmly but not rigidly. They are able to move around one another freely, resulting in a limited degree of particle mobility. This freedom for the molecules to move results from the temperature of the material. Heat is the vibrational motion of the molecules, so asAs the temperature increases, the increased vibrations of the molecules causes distances between the molecules to increase. When a liquid reaches its boiling point, the cohesive forces that bind the molecules closely together break, and the liquid changes to its gaseous state (unless [superheateding] occurs). If the temperature is decreased, the distances between the molecules become smaller. When the liquid reaches its freezing point the molecules will usually lock into a very specific order, called crystalizing, and the bonds between them become more rigid, changing the liquid into its solid state (unless [supercooling] occurs].
Esben (talk) 10:36, 13 December 2009 (UTC)
That looks good to me. I still think we could use a paragraph covering structure, but that can come later. I think this is enough to insert into the article for future expansion. Zaereth (talk) 17:22, 14 December 2009 (UTC)

Since there has been no other comment, I have added this to the article. thanks Esben for your help! Zaereth (talk) 18:54, 16 December 2009 (UTC)

Immiscibilty and thermal expansion[edit]

I have a question. Do these two items belong in the phase transition section, where they are now, or should these be in the properties section?

I think these two sections could probably go into a little more detail, such as the compressability of liquids. It's usually not a factor, until dealing with high pressure hydraulics. I'll have to dig up the actual numbers, but as I recall, oil will usually compress by about 0.5% in volume at 4000 PSI (275 bar), and 4% in volume at 10,000 PSI (690 bar). Compressability becomes a major factor in systems that operate in the 20,000 to 50,000 PSI range (1400 - 3450 bar). I'll see what I can find for some of this info, and try to start an application section as well. Zaereth (talk) 01:01, 18 December 2009 (UTC)

Immiscibilty should definitely be moved and expanded; it is on my todo list if noone beats me to it. Compression of liquids is outside my knowledge, but sounds relevant. Esben (talk) 07:23, 19 December 2009 (UTC)
Spellcheck: compressibility :-) -- logger9 (talk) 01:35, 19 December 2009 (UTC)
Hmmm. :-/ I thought it looked funny, but almost never spellcheck on talk. Thanks, and happy holidays! :-D Zaereth (talk) 02:04, 19 December 2009 (UTC)

Application section[edit]

I have started an application section, but it could probably use a little expanding, as I don't have much info to add on uses such as solvents, acids and others. It could probably use some info on liquid's use in measurement, like thermometers and manometers. Does anyone have any comments, or anything to add? Zaereth (talk) 21:44, 21 December 2009 (UTC)

Liquids have a variety of uses, as lubricants, solvents, and coolants. In hydraulic systems, liquid is used to transmit power.

In tribology, liquids are studied for their properties as lubricants, to reduce friction between moving parts. Lubricants such as oils are often chosen for viscosity and flow characteristics that are suitable throughout the operating temperature range of the component. Oils are often used in engines, gear boxes, metalworking, and hydraulic systems for their good lubrication properties.[1]

Liquid is the primary component of a hydraulic system, which takes advantage of Pascal's law to provide fluid power. Devices such as pumps and waterwheels have been used to change liquid motion into mechanical work since ancient times. Oils are forced through hydraulic pumps, which transmit this force to hydraulic cylinders. Hydraulics can be found in many applications, such as automotive brakes and transmissions, heavy equipment, and airplane control systems. Various hydraulic presses are used extensively in repair and manufacturing, for lifting, pressing, clamping, and forming.[2]

Liquids tend to have better thermal conductivity than gases. The ability to flow makes a liquid suitable for removing excess heat from mechanical components. The heat can be removed by channeling the liquid through a heat exchanger, such as a radiator, or the heat can be removed with the liquid during evaporation.[3] Water or glycol coolants are used to keep engines from overheating.[4] Water or liquid metals, such as sodium or bismuth, have been used as coolants in nuclear reactors.[5] Liquid propellant films are used to cool the thrust chambers of rockets.[6] Water and oils are used to remove excess heat generated during machining, which can quickly ruin both the work piece and the tooling. During perspiration, sweat removes heat from the human body by evaporating. In heating, ventilation, and air conditioning (HVAC), liquids such as water are often used to transfer heat from one area to another.[7]

I did a little research over the holiday to come up with some uses for solvents, and added it to the above. I've gone ahead and placed this section into the article. Zaereth (talk) 21:16, 28 December 2009 (UTC)

Hidden structure[edit]

This section seems totally unclear and redundant to me. What it tells beyond the existence of short-range order in liquids as follows from the radial distributions (something that has been already described in the previous section about correlations)? Biophys (talk) 03:34, 19 August 2010 (UTC)

I tend to agree, for I really have no idea what those subsections are trying to say. An introduction paragraph for these subsections, and those in the "dynamics" section too, would definitely be helpful to me. If anyone who understands them can do this it would be much appreciated.
On a similar note, I am wondering if "dynamics" is the proper title for that section. To me, liquid dynamics generally refers to large-scale flow effects, like eddie currents and cavitation, so it seems a little surprizing to find only a discussion of molecular dynamics there. Zaereth (talk) 18:42, 19 August 2010 (UTC)
Yes, the "molecular vibrations" sub-section is also out of place and tells little.Biophys (talk) 02:14, 20 August 2010 (UTC)

@Logger9[edit]

Logger9, please slow down. You are again inserting huge blocks of text, here and in glass transition and who knows where next.

Andrade focused his studies...

Who cares? Who does know Mr. or Ms. Andrade? You cannot start a section with such an unmotivated history-of-discovery.

and cited Lindemann's theory of melting

Again, who cares that A cited L's theory? If L's theory is relevant, then write a short article about it, instead of summarizing it in similar terms in different articles.

Another problem is your choice of references, mostly several decades old. If those old ideas were still relevant today, they should have made it into review articles and textbooks. In general, it should not be necessary to cite the original papers. On the contrary: assembling an arbitrary choice out of the tens of thousands of orginal papers on liquids and glasses is creative work in its own right - and therefore a violation of Wikipedia's policy no theory finding.

-- Marie Poise (talk) 08:58, 12 November 2010 (UTC)

Melting is at best a marginal aspect in the vast topic "liquid". I suggest the new section on melting be transferred to melting. -- Marie Poise (talk) 19:33, 12 November 2010 (UTC)

Support as a general approach. This is a simple management rule (speaking to Logger): keep a major text in one place, so that it can easily be fixed in that place. Copying it between a dozen of articles makes it very difficult to synchronize the corrections. We've got wikilinks and {{main}}/{{Seealso}} templates for that. Materialscientist (talk) 23:55, 12 November 2010 (UTC)

Solution section[edit]

I'm getting a little out of my field when I start talking chemistry, but it seems odd to me that the solution section only describes immiscibility. I may be wrong, but many definitions I've seen describe a solution as a solid dissolved into a liquid and miscibility as a two liquids disolved into each other. Other definitions descibe both miscible and a solution as a homogenous mixture of liquids and/or solids, while immiscible/insoluble is a mixture that will eventually separate. Other definition describe a solution as a homogenous mixture and miscible as more of a suspension.

It's a bit confusing. I hope that someone who understands it better than me can sort this out. I also think we should describe how liquids can sometimes dissolve solids as well as other liquids, and how immiscible liquids can form emulsions. It might be worth mentioning something about acids and bases as well. Just a thought. Zaereth (talk) 01:55, 13 January 2011 (UTC)

Iodine[edit]

Iodine should be excluded from the list of elements liquid at slightly above room temperature since its melting point is higher than the boiling point of water, not to mention the melting points of sodium and potassium.Syd Henderson (talk) 21:29, 2 August 2011 (UTC)

Agree. Further, while it is easy to dissolve, it is difficult to melt because of sublimation. I went ahead and removed it. Materialscientist (talk) 22:33, 2 August 2011 (UTC)

Immiscibility of hot and cold water[edit]

One of the pictures has this caption: "Thermal image of a sink full of hot water with cold water being added, showing the immiscibility of the two liquids." This is not correct. Immiscibity refers to two liquids that won't mix. That's not true of hot water and cold water. In fact, they're miscible, not immiscible. It's an interesting picture, and it illustrates how liquids flow. But it does not illustrate immiscibility of hot and cold water. I've revised the caption. Omc (talk) 01:12, 9 October 2012 (UTC)

Good job! Polyamorph (talk) 15:26, 9 October 2012 (UTC)
You're probably right in that immiscibility was not the best choice of words. The main point I was trying to demonstrate is that they do not readily mix, but the cold water will fall to the bottom and they will stratify. This is a common occurance in heating and thermal storage systems, and can easily be experienced in a bathtub. Unfortunately, the thermal camera can't see through glass, so my photo of the actual stratification was far less impressive. Zaereth (talk) 17:58, 9 October 2012 (UTC)

Abundance of liquids in the universe[edit]

A recent addition was made to the article, I believe in very good faith, but it is unsourced and doesn't seem to completely hold to the known facts about the universe. I had thought about cutting it, but then tried to copy edit and correct it a bit. However, the more I consider it, I'm thinking it should be cut until sources can verify the accuracy.

The main thing that strikes me is the statement that liquid is the least abundant type of matter in the known universe. The reason I say this is because many the gas giant planets are believed to have liquid cores. Liquid methane rains and forms lakes on Titan. Enceledus may be composed mostly of liquid water. The Earth itself, besides being covered with water, is made mostly of liquid rock and metals with a thin crust of solid. The other rocky planets are believed to have similar liquid cores. Just in this solar system alone the abundance of liquid is probably much greater than solids, and maybe even gases.

Should this be cut, or does anyone have some sources which can improve the sccuracy of the statement? Zaereth (talk) 23:17, 18 October 2012 (UTC)

You mention that certain moons and planets may have liquid in them, but you fail to realize that these bodies are absolutely miniscule in comparison to the immense sizes and masses of stars and interstellar clouds, which are made mostly of gas and plasma, with small amounts of solid matter mostly in the form of dust. It is also worth mentioning that I am talking about baryonic matter that we can easily observe, not dark matter or any other exotic matter. I just added that info on a whim, but I am fairly confident that credible sources exist to confirm this piece of knowledge I remember reading a long time ago. Cadiomals (talk) 23:37, 18 October 2012 (UTC)
Yes, I agree that, universally, gas and plasma and dark matter far outrank both liquids and solids. The question, are liquids more prevalent than solids? Zaereth (talk) 23:51, 18 October 2012 (UTC)
By the way, I didn't mean cut the entire thing, just that one point. It would be nice if someone, somewhere had some info, because with all the new planets and stuff being discovered I'd really like to know. Zaereth (talk) 00:32, 19 October 2012 (UTC)

Statistical theory of liquid state - references[edit]

  • J.G. Kirkwood, J. Chem. Phys. 3, 300 (1935)
  • J.E. Mayer, J. Chem. Phys. 15, 187 (1947)--82.137.9.33 (talk) 10:29, 30 October 2013 (UTC)

Liquids in space[edit]

It makes perfect sense that a liquid should not be able to exist in the vacuum of space, but my question is, does this apply to all liquids? In specific, to liquid rock and metals? I ask, because I see multiple sources that say the rocky planets and asteroids formed from molten lava, Vespa being a prime example, so I am wondering if liquid rock can exist in space? I assume that these things were liquid in the early development of the solar system. Liquid rock is by far the most abundant liquid within the Earth. Can this lava exist in a vacuum, or would it also sublime into a gas until it reaches enough gravitational pull to condense in to a liquid? (I find no sources that go into that level of detail.) Zaereth (talk) 23:23, 28 October 2014 (UTC)

Come to think of it, all of my high-vacuum pumps use vacuum oil to help draw the vacuum (and also to absorb moisture), and mercury can also exist in near total-vacuum, which is why it is used for very-deep vacuum measurements. Zaereth (talk) 23:43, 28 October 2014 (UTC)

  1. ^ ’’Lubricants and lubrication’’ by Theo Mang, Wilfried Dressel – Wiley-VCH 2007
  2. ^ Fluid power dynamics By R. Keith Mobley - Butterworth-Heinemann 2000 Page vii
  3. ^ ’’Handbook of thermal conductivity of liquids and gases’’ by N. B. Vargaftik – CRC Press 1994
  4. ^ ’’Automotive technology: a systems approach’’ by Jack Erjavec – Delmar Learning 2005 Page 309
  5. ^ ’’The prospects of nuclear power and technology’’ by Gerald Wendt – D. Van Nostrand Company 1957 Page 266
  6. ^ ’’Modern engineering for design of liquid-propellant rocket engines’’ by Dieter K. Huzel, David H. Huang – American Institute of Aeronautics and Astronautics 1992 Page 99
  7. ^ ’’HVAC principles and applications manual’’ by Thomas E Mull – McGraw-Hill 1997