Talk:Water (molecule)

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This article could be improved by expanding the "water in biology" section, e.g. including the role of water in cell metabolism (hydrolysis reactions) and oxygen-formation by water-splitting in plants. - tameeria 05:21, 19 February 2007 (UTC)
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[edit] Compressibility

The compressibility and the bulk modulus should be reciprocals of one another, but the values given in the article are not: therefore one of them must be wrong. I suspect that the value given for the compressibility is missing a power of ten (perhaps the units should be Mbar^(-1)?). The value for the bulk modulus is not useful, since it does not specify what conditions of temperature and pressure it is obtained at.

I've amended that section after looking up the reference. It was only out by six orders of magnitude.  ;-)
129.16.97.227 20:06, 6 June 2007 (UTC)

Still I think the figures in this section far out. I do not have all the right figures,but I know that at 1000 bar water is compressed bij about 4 % as compared to standard pressure. In my opinion this should mean that roughly on average compressibility is 0.04 per 1000 bar or 0.00004 bar-1 0r 4·10-5 bar-1 http://runt.ocean.washington.edu/swift/PTV-manual/node27.html (1 bar is approx 14.5 PSI) This and other links confirm this. —Preceding unsigned comment added by 83.116.231.1 (talk) 08:11, 8 October 2007 (UTC)

[edit] Why is it called OH, not HO?

Since my teacher at collage could not answer this question I'll ask it here: Why is it called OH in reaction formulas and not HO? I don't se the logic behind it. Surely it has historical reasons but then why is the sulfur compound is called HS? Could some please tell me more about why this is so? There has to be a reason. /curious collage student in Uppsala. —Preceding unsigned comment added by 130.243.221.26 (talk) 20:18, 17 October 2007 (UTC)

Because, thanks to Jesse Jackson, it is not longer acceptable to label anything as a HO.
Seriously, though, this is not a forum for discussing the topic, it is a forum for discussing the article. Please do not make forum-like posts on this page, even if you are studying collage. --Jaysweet 20:22, 17 October 2007 (UTC)
I am serious, besides; I really do think it is older than this and as far as I know Jesse Jackson has nothing to do with chemistry. Can someone more knowledgable person please give the hisorical reasons for my question? /student in Uppsala.
It is my contention that it doesn't really have a formal way to be written. I think that both ways of writing the chemical are acceptable. I think that OH is often written as such because it is a common functional group with the R' group being attached to the O and not the H, such as CH3COOH. Written as a stand-alone molecule it is written as H20 or H02. I think it has become somewhat arbitrary dogma, because as you should know by now, the chemical compound does not change, whether you write it one way or the other. You could also check out SMILES to see if you answer is in there. 146.244.241.204 (talk) 19:43, 28 April 2008 (UTC)niubrad

[edit] Physics and Chemistry

The Temperature and Density table is so inaccurate it's not even funny. It completely contradicts everything else the article says. Someone please fix it. —The preceding unsigned comment was added by 65.40.167.36 (talk) 19:21, 27 February 2007 (UTC).

Could you be more specific? Or better yet, fix it yourself? Itub 10:53, 28 February 2007 (UTC)

[edit] Surface tension error

The surface tension of water at 20 C is 0.0728 N/m, not 7.28 N/m.

[edit] Water is NOT the universal solvent

Water is NOT the universal solvent. There is no such thing. Please review your solubility rules. AStudent 06:30, 16 July 2006 (UTC)

If there was...what would you store it in? - Jack (talk) 00:00, 19 July 2006 (UTC)
A frozen block of the same substance? DMacks 02:14, 19 July 2006 (UTC)
Nope, that wouldn't work, the liquid and solid form would be in thermodynamic equalibrium with each other. The solid form would melt (disolving the thing it was on/in) or the liquid form would freeze, becoming one with its container (thus rendering it useless as a solvent).
You made me panic for a second! almost thought you'd answered one of my favourite rhetoric questions, like "what colour is paint?" - Jack (talk) 02:50, 19 July 2006 (UTC)
Yeah, was meant mostly as a mu answer. But "thermodynamic equilibrium" wasn't part of the question, nor does something have to be at a uniform temperature to have reached a steady state...what if we keep slightly cooling the bottom and maybe sides of the solid and put a small heat source just above it? DMacks 05:07, 19 July 2006 (UTC)
Could work... But as with any liquid, you couldn't stop evapouration and the vapour would condense on the cooler, corroding it a bit, then a lot, untill it eventually ceased to work. The heater would melt the block, and from then all is lost. This universal solvent; was it supposed to dissolve anything, or any amount of anything? Sounds a bit like the grey goo hypothosis to me - Jack (talk) 16:06, 19 July 2006 (UTC)
Water is called the universal solvent because it will dissolve most substances put into it, given time, if these substances are in a manageable form. Water dissolves sugar, salt, HCl... No one is suggesting that water will eat away at each and every substance on the face of the earth. All that's being said here is that most substances will dissolve in water. Maianess 22:03, 19 November 2006 (UTC)
The only container for a universal solvent -- assuming it is heavier-than-air -- would be the center of the Earth. Or another celestial body. Or in orbit, or floating in space. Kejo13 (talk) 16:56, 22 February 2008 (UTC)
Duck Tape smeared with twinkeys and peeps, cover that with dated McDonalds chicken nuggets, rhino lining, and the Bush Iraq policy. Nothing will break it down, guaranteed. 146.244.241.204 (talk) 19:53, 28 April 2008 (UTC)niubrad

Water is called the universal solvent, and of course anything we observe we do so from an anthropomorphic viewpoint. But the point is it is a well established phrase, that is commonly used. Objectively there is no such thing as a universal material at all, there are only physical laws which to best of our knowledge act universally. So in the end the physical parameters at a certain location determine what is entropically and energetically etc... favorable.—Preceding unsigned comment added by Slicky (talk • contribs)

I agree with Maianess. Just because water dissolves very many different materials does not require that it dissolves large quantities of them. Martin Chaplin (talk) 17:07, 22 February 2008 (UTC)

There's no need for discussion of universal solvents in an article on the water molecule (or at least, water from a chemistry perspective). It's all waffle. Water does not dissolve most things.
If a universal solvent did exist, maybe you could contain it with an electric or magnetic field of some kind. But this is not really an issue, as no such substance exists. Fluorine is perhaps the closest you can get, but it's not so much a solvent as just very reactive.
Ben (talk) 19:22, 22 February 2008 (UTC)

[edit] Self Ionization

Shouldn't there be a section on self-ionization of water, or at least a proper link to that page somewhere? I'd think it is a rather important property of the water molecule and is mentioned in passing in the Electrical Properties section. Harperska 22:00, 8 September 2006 (UTC)

[edit] Specific heat error

Looks like the specific heats of water as vapor and water as liquid are reversed. Maybe just a labeling problem.

Fixed... I hope --Steven 04:18, 10 December 2006 (UTC)


[edit] Cv < Cp

My Primary reference is Physics for Scientists and Engineers, third edition by Raymond A. Serway. On page 566 it has the formula Cp − Cv = R. This is the same as saying Cp = Cv + R. In other words Cp > Cv. On the same page, the book also lists the Cp of gaseous H2O at 300^\circ K as 35.4 J/({mol} \cdot K) and the Cv at the same temperature as 27.1 J/({mol} \cdot K). On page 564 it lists the molar weight of H2O as 18g / mol. Using these figures and rounding to three significant digits C_p = 1970 J / (kg \cdot K) and C_v = 1510 J / (kg \cdot K) at 300^{\circ} K. Using the Water_(data_page) you get C_p=2030 J / (kg \cdot K) and C_v=1530 J / (kg \cdot K) at 100^{\circ} C. None of the numbers for Cv are even close to what is actually in the article. I used the numbers from Serway because, at 300^{\circ}K or 26.85^{\circ}C it is closest to the standard temperature of 25^{\circ}C stated at the bottom of the table. I hope this is OK.

Commdweeb 17:20, 9 February 2007 (UTC)

[edit] Fahrenheit

I removed much of this because it stated "100 degrees was set at body temperature (now accepted as 98.6 degrees) and 0 degrees at the temperature at which equal parts of salt and water melt." This is incorrect (and somewhat irrelevant, body temperature being discussed in a water article like this?). It was initially based on the boiling point of water at 60 degrees, then he did a bunch of multiplication and wound up with 212. Zero degrees was colder than it got in Denmark (Fahrenheit hated negative numbers). See citation (at straightdope.com) for more information.Squad51 02:19, 19 November 2006 (UTC)

[edit] Oxane?

I've been trying to find a source for the claim that "another systematic name that has been accepted by IUPAC is oxane." All I could find, however, is a recommendation giving "oxidane" as the systematic name, saying that "the names aluminane, bismane, oxane, thiane, selenane, tellurane and polonane cannot be used since they are the names of saturated six-membered heteromonocyclic rings based on the Hantzsch-Widman system." (It further states that "the names 'azane' and 'oxidane' are only intended for use in naming derivatives of ammonia and water, respectively, by substitutive nomenclature.")

The specific table I linked to above is marked as "provisional", but the exact same recommendation can be found in other IUPAC documents, such as the Principles of Chemical Nomenclature, page 99. Given this, I believe the description of "oxane" as an accepted synonym should be corrected. —Ilmari Karonen (talk) 19:11, 15 December 2006 (UTC)

...as I have, now. —Ilmari Karonen (talk) 23:31, 15 December 2006 (UTC)

[edit] "Pure Water"

I have removed the following statement:

Pure Water
Water is often viewed as simply two Hydrogen molecules and one Oxygen molecule, however water is a much more dynamic creature.

and a subsequent list of the "components" of water as being H2 and friends, in some sort of equilibrium, and now it's been re-added, so let's consensus-ize. Do people really often think this? Is it true even at a microscopic-reversability level (which isn't how people "often" look at it outside of labs, but anyway...)? And should we bother explaining what we mean by these molecules if it's not even how water actually is? Also, tritium is listed (in a confusing notation, but let's deal with the concept first)...is there any non-negligible tritium content in non-enriched water? DMacks 22:22, 12 February 2007 (UTC)

[edit] Does water break up in nature?

in photosynthesis and stuff is water broken into hydrogen and oxygen. Some stuff seems to say that water is created in carb metabolism, but isn't the water just stuck in the middle of that carbohydrate and just gets released? Puddytang 22:40, 26 February 2007 (UTC)

[edit] Year of Celcius scale reversal?

This article states "The scale was reversed in 1744". The Anders_Celcius article states "The scale was reversed by Carolus Linnaeus in 1745, to how it is today". Presumably one is right and one is wrong.88.104.193.229 03:57, 13 April 2007 (UTC)

[edit] Hydric acid?

Perhaps it should be mentioned that "hydric acid" is an incorrect name, because ALL acids contain hydrogen and dissociate into H+ and some other ion? It's more like hydroxyl acid. Or you should remove "hydric acid" altogether.

[edit] Article is mostly not about the molecule...

This article generally isn't about water the molecule, but water the macroscopic substance. Liquid water, ice, etc. Why then is the page titled Water (molecule)? Surely something like Water (substance), Water (compound) or even Water (chemical) would be more appropriate? 129.16.97.227 20:14, 6 June 2007 (UTC)

[edit] Water in Biology section is too short

Why isn't there more on water in our bodies and water in animal bodies. I don't know much about water but when I loooked up this article, I was hoping to see more information on how much of our bodies are water, why our bodies need water, what do our bodies do with the water when we drink it, etc. Can someone expand on the tiny "Water in Biology" section or advise where to look. Thanks! --Mezaco 19:03, 12 June 2007 (UTC)

Did you look at the Water article? That one is supposed to cover those topics in more detail. This article (Water (molecule) focuses more on the chemistry. --Itub 08:43, 25 June 2007 (UTC)

[edit] electromagnetic absorption spectrum

Does anybody have access to the journal Applied Optics? I'd appreciate a copy of this article to cover this important aspect in the article. Bendž|Ť 15:17, 27 August 2007 (UTC)

[edit] O RLY?

The density of water is dependent on the temperature of the water. This is because the density is different for salt water than for fresh water.

So you're telling me that temperature is a property conferred by salinity? Interesting. Especially since it's totally wrong, and these two statements taken together are 100% non sequitur. --75.49.222.55 03:54, 9 October 2007 (UTC)

[edit] cleanup-combine

I have organized the article. Possible duplicate content marked as small text should be embeded into article. Task for someone with better English and with better chemistry & physics knowledge than me. Thank you for cooperation. --Snek01 (talk) 22:30, 15 December 2007 (UTC)

[edit] Symmetry

A while back I added the point group C2v to the property box on this page and linked to the page on molecular symmetry, which was subsequently removed. This is actual info' on the structure of the compound as this page is meant to convey and has previousluy been argued to be missing. I would propose that for all simple molecules (BF3, NH3, etc. ie excluding most large molecules whose only symmetry is the identity) that this info' be added. It is important data for understanding and deriving electronic configurations and bonding as well as giving info on chirality, dipoles etc. There is alot of editing needed on this page, and removal of useful facts does not help it. —Preceding unsigned comment added by Azo bob (talk • contribs) 22:03, 14 January 2008 (UTC)

I agree 100%. 129.16.97.227 (talk) 15:46, 17 January 2008 (UTC)

[edit] Other liquids that are less dense when frozen

I am having some trouble deciding what other elements besides water will expand when frozen, according to this article. In the section called Density of water and ice, according to the text, "Water, lead, uranium, neon and silicon are some of the few materials which expand when they freeze". To me, this indicates that lead, uranium, neon and silicon are less dense in the solid state than in the liquid state.

However, if you read on in the same section, you can read that "Water shares the higher-density liquid state with only a few materials like gallium, germanium, bismuth and antimony." Now it seems that gallium, germanium, bismuth and antimony are actually the elements that are less dense as solids than as liquids. So which group of elements is actually less dense as a solid than as a liquid? Or, is it all of the aforementioned elements? If so, the section should be re-worded so that it is more clear. --Ean5533 ( View! / Talk!) 00:06, 16 February 2008 (UTC)


HEAT CAPACITY ANYONE?! Thanks for heat of vaporization... tho. Alex. —Preceding unsigned comment added by 128.46.105.47 (talk) 02:00, 24 April 2008 (UTC)

[edit] Data for real water?

This data appears to all be for pure water only. The article should state this limitation clearly at the start. Having such chemical-theory data is a good start, but most of us are dealing with real water: tap water, rain water, lake water, sea water, etc. We want density etc data for real water. Where can one find data on the physical properties of real water? -69.87.199.87 (talk) 11:08, 6 June 2008 (UTC)

Well, insofar as it differs from that of pure water, it's obviously going to depend on the source of the water in question. The biggest variable in general (excluding nonchemical issues such as suspended solids) is probably going to be salinity, for which you might be interested in our article on seawater. —Ilmari Karonen (talk) 13:44, 6 June 2008 (UTC)
We also have an article on tapwater. —Ilmari Karonen (talk) 13:45, 6 June 2008 (UTC)