Talk:Water (data page)

Entropy of evaporation
I believe there is an error in the dataset. The latent entropy of evaporation is listed as 109.02 J/mol/K, but this should equal the latent enthalpy of evaporation divided by the temperature of vaporization, which is 107.195 J/mol/K. In contrast the latent entropy of freezing is 22.0, which agrees well with the computed value of the latent heat of freezing divided by the melting temperature, 22.0026.

If you integrate the heat capacity to compute the enthalpy and entropy of the solid, liquid, and vapor phases, which allows determination of the Gibbs free energy curves, you will find that using the value of 109.02 shifts the vaporization point away from the true vaporization temperature 373.15.

I posted a video showing an analysis of this YouTube at otn8_YtqXCE

If there is interest, I can provide the computed curves of the enthalpy, entropy, and Gibbs free energies. Scott.beckman (talk) 18:11, 8 March 2022 (UTC)

heat of evaporation
I was looking for the heat of evaporation (i.e. turning water that is already at 100 degrees centigrade into steam of 100 degrees centigrade).

I can't find that data on this page, and it lacks explanation of the meaning of what it does present, so that it is unfortunately not usable by me.

Fortunately, searching wikipedia for 'specific heat capacity' and 'heat of evaporation' does provide the needed data. Specific heat 4.2 J/gram Kelvin Evaporation 2260 J/gram So evaporation equivalent to 538 Kelvin temperature increase.

I would like these data to be linked from 'water'. I hope this 'talk' page does that, but it would be better if these data were added to the main physical properties table (as they are for other substances).

See Wasser (Stoffdaten) for some tables which could be easily translated. --Saperaud 07:08, 9 October 2005 (UTC)


 * I am endeavoring to translate the material and post the result on water (data page). Karlhahn 17:13, 12 October 2006 (UTC)

Notable safety precautions
"The handling of this chemical may incur notable safety precautions. It is highly recommend that you seek the Material Safety Datasheet (MSDS) for this chemical from a reliable source such as SIRI, and follow its directions."

Umm... it's water. Need I say more?

Overdosing on water can create an electrolyte imbalance in your body and kill you. So don't drink too much water.


 * Why is this part even included? Is it to conform to some sort of stanards materials page? If not, I'd say remove it. It makes the whole thing look like a joke. --Alf 20:54, 24 July 2006 (UTC)

I agree that the safety precautions does not belong here. First, if you want jokes, go to a comedian nightclub, not wikipedia. Second, it's not data. If there are no objections, I'm going to take it out this weekend. Karlhahn 12:42, 6 October 2006 (UTC)

Specific density
I came to this page from the main water page looking for specific density. When I didn't find it here I googled it, and was embarrassed to find the answer (because it's such a gimme). Of course it's a no-brainer for many people, but for those of us having a Homer moment, or who haven't done anything with science since high school, wouldn't it be a good idea to include it? I am not familiar with the chemistry pages so I don't know where to add it. For an example of some of the data that could be added to the water data page, see Hydrochloric Acid.--Anchoress 14:55, 1 February 2006 (UTC)


 * Added densities at various temperatures to this page today. Karlhahn 19:35, 1 October 2006 (UTC)


 * It seems that this table has different values from the one at Water (molecule), Am I correct or have I overlooked something. I compared the values at 4 degrees Celsius, which here is said to be 1g/cm3 whereas in the other article it says 0.9999720 g/cm3.


 * Fixed table. Units should have been g/ml. Added conversion factor in table header. Density at 4°C now agrees with both CRC 44th ed., page 2190 and with Langes 10th ed, page 1199. Karl Hahn (T) (C) 11:49, 26 September 2007 (UTC)


 * Is that the "To convert to g/cm^3, multiply g/ml by 0.999973". This seems wrong. 1 litre = 1 dm^3 (Concise Science Dictionary 1988) so 1 cm^3 = 1 ml exactly. Different densities in different sources may be that before 1964 a litre was slightly larger, in fact 1 dm^3 was then 0.999972 l (Litre). The values in Water (molecule) is probably more right. /David A 85.231.140.117 —Preceding signed but undated comment was added at 21:56, 29 September 2007 (UTC)


 * Moreover, Wikipedia itself defines Litre as 1 dm^3, so this conversion factor should probable be dropped.--81.34.28.87 (talk) 18:09, 22 November 2007 (UTC)


 * The confusion with converting g/ml to g/cm³ arose due to obsolete usage of the definition of Liter (see History section), although the quoted source probably had the units right at that time. I converted the data to modern units. Xenonice (talk) 22:05, 26 November 2007 (UTC)


 * Table still doesn't agree with the densities on Water (molecule). According to Water (molecule), the density at 298K should be 0.99705, but it is listed here as 0.99704.  Could someone provide numbers that are from a modern, verifiable source that doesn't require archaic conversions based upon old and new definitions of a liter? 142.165.199.82 (talk)  —Preceding undated comment added 22:48, 28 July 2011 (UTC).

Water reheating
How many times can you reheating water in a kettle... is it safe to reheat especially when useing to feed new born babies− —The preceding unsigned comment was added by 82.45.231.180 (talk) 18:43, 7 February 2007 (UTC).


 * It probably depends on the quality of tap water and on what the kettle is made out of. Usually kettles accumulate deposits of weakly-soluble residues inside. Reheating can put more of that residue back into the water. Also, repeated reheating can dissolve some of the kettle material into the water. Both effects are probably harmless (as long as the kettle material doesn't contain toxic substances). Xenonice (talk) 22:05, 26 November 2007 (UTC)

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. Until such is added, please add at least links to such data! -69.87.199.87 (talk) 10:20, 6 June 2008 (UTC)


 * Unfortunately, there are no measurements for tap water, because tap water depends entirely on your tap, and varies widely between various cities, countries, etc... It may even differ for nearby buildings in the same city. Pure water is is the only way to have a true standard. Fortunately, if you want to know the density of "real" water (that you have in your glass), all you have to do is measure it's volume (in milliliters if you like) and then it's mass (maybe in grams). (Be sure to measure and subtract out the weight of your empty glass.) Divide these quantities, and you'll find that the density of tap water is very close to that of pure water, at about 1g/mL. Zolot (talk) 22:40, 31 July 2009 (UTC)

ethyl acetae colum
i want to know about ethyl acetae distilation colum which use in acephate (pesticides ind.)plant —Preceding unsigned comment added by 220.225.57.24 (talk) 04:33, 17 December 2009 (UTC)

Steam Tables
I applied the formula presented in the Steam Table section and noticed a difference between the table listings and the computed results. Which is more accurate? It seems, based on an example I've seen, that the computed value is more accurate. I'm not really sure? I think it would be good to include a comment about this in the section. Also, I remember reading that there are multiple ways to calculate the values, perhaps a reference to this could also be useful?

Pooven (talk) 10:19, 12 March 2010 (UTC)

Specific entropy
How is it that the specific entropy (i.e. the entropy per kilogram) is negative in the first line of the German steam data table?

This must therefore be a relative entropy; but what is it relative to -- ie what is the zero on the scale? And why not give the absolute entropies ? Jheald (talk) 20:25, 20 April 2010 (UTC)

Surface Tension
While at a recent colloid and surface chemistry conference, came across the fact that the surface tension of pure water is not actually ~73 mN/m. Well, OK, yes that is the value you will measure after a few tenths of a second. However, on shorter time frames, it is actually higher, in the region of 80 to 85 (hard to pin down due to how quickly it changes etc). The reason for this is due to the surface activity of the hydroxide ions that spontaneously form.--Dr DBW (talk) 01:06, 24 March 2011 (UTC)

Recent work, new phases predicted.
Recent ab initio work predicts new phases including metallic ice at >15.5 MBar pressure. Here: http://militzer.berkeley.edu/papers/ice26.pdf   58.165.80.74 (talk) 13:22, 16 September 2012 (UTC)

Units
Is there a good reason that this page is in such bizarre units? Surely we should either adopt SI (density in kg/m3, heat capacity in J/kg, ... and what on earth is a dyn/cm? I'd vote for SI and copy in BTU etc, but the present units are mad! If I understood editing in Wikipedia myself, I'd make the obvious changes. — Preceding unsigned comment added by 206.47.106.180 (talk) 11:11, 28 January 2014 (UTC)

Hardness and brittleness of ice
There is not a word about hardness! And fewer about brittleness.

Down to ca -10 °C we all know that our icecubes are very brittle and can be splintered easily. It is less known that at -20 ice is very hard, If you hammer an iceaxe into it, it does not get stuck, so that you can hang on it, it jumps back into your face. Ice-climbers know (or learn) to stay home when it is cold. On Mars the Phoenix lander in 2008 had large problems scraping some ice loose from the small exposure called Holy Cow - temperature was around -60. Steen Thomsen (talk) 16:05, 22 December 2023 (UTC)