Talk:Urea

message: Hang on, At least sharks produce urea and they are aquatic. — Preceding unsigned comment added by 213.167.138.65 (talk) 09:56, 9 July 2004 (UTC)
thread_title: Sharks

message: Someone changed the 'Lab use' section to say that it is used in concentrations up to 10M (rather than 6M, as it said before).  I don't think that you can actually make a solution of urea that concentrated, at least under mild conditions.  I'll leave it as I don't know for sure, but this may be inaccurate. ike9898 14:17, Feb 2, 2005 (UTC)
:According to a MSDS I found, solubility at 74 F is 119g/100g water.  This works out to 10.5M assuming densities of solution is additive and sp gr's water 1.00; urea 1.34.  This is a very conservative assumption, so if data is right 10M should not be a problem!  (A 10% soln. has sp gr of 1.14 or 1.9M (6th Merck Indx); using above assumption sp gr would be 1.03 or 1.7M (thus underestimating Molarity)) DEN 6/10/05 — Preceding unsigned comment added by 208.230.167.50 (talk) 15:14, 10 June 2005 (UTC)
thread_title: Possible inaccuracy

message: Sigma-Aldrich is one of the largest chemical supply companies for labs, I have just looked in their catalog and they have 8M Urea avalible.
http://www.sigmaaldrich.com/Brands/Sigma/Sigma_General_Catalog.html
Onco p53 19:48, 2 Feb 2005 (UTC)
thread_title: Sigma-Aldrich

message: How did the early chemists isolate urea from urine or other biological samples? — Preceding unsigned comment added by 129.78.64.104 (talk) 01:49, 9 March 2005 (UTC)
thread_title: Early chemists

message: I would like to comment on this page from the perspective of a high school student taking a biology course. This article on urea is very informative about the composition and alternative uses of urea, but I frankly am totally lost as to what urea actually does in its natural function. Perhaps some description of its function, or at least something clearer (in case I simply cannot discern its function)would add to the usefulness of this article. — Preceding unsigned comment added by 199.216.81.20 (talk) 19:26, 2 November 2005 (UTC)
replies: text: It's a waste product from amino acid metabolism. It has no intrinsic function. JFW | T@lk 20:44, 2 November 2005 (UTC)
replies: text: Wait, if it has no nutritional function at all, why does the yeast nutrient I use in homebrewing contain it? Does yeast have some use for it? teucer 01:22, 19 November 2005 (UTC)
replies: text: This paper proposes that urea somehow protects yeast cells from being poisoned by the ethanol they are producing by sequestering inorganic pyrophosphatase (the enzyme that yeast use for inaerobic respiration to make ATP) away from the ethanol. The interesting thing is that urea itself is a protein denaturant (as is ethanol).--Cowbert 23:29, 25 April 2006 (UTC)
replies: text: Please check under "Physiology" section.  It has been updated. Urea is vastly important. Yay to a high school student for pointing that out. A0900 06:50, 30 October 2007 (UTC)
thread_title: Natural function

message: In the discovery section, I see the following:
"Although Rouelle was attempting to prepare ammonium cyanate, he inadvertently disproved the theory that the chemicals of living organisms are fundamentally different from inanimate matter by forming Urea, thus starting the discipline of organic chemistry."
Is this about Rouelle or Woehler? I am vaguely familiar with Woehler's story, and this seems like a small typo, but I'd like someone more authorative to make the call. — Preceding unsigned comment added by Jormundgard (talk • contribs) 05:36, 18 December 2005 (UTC)
thread_title: Rouelle or Woehler?

message: Sweat contains how much urea normally, please ?  --213.7.155.164 11:46, 12 January 2006 (UTC)
thread_title: How much in sweat?

message: I may be wrong, but I was comparing the definition for urea on wikipedia with the definition in my copy of Merriam-Webster's Medical Desk Dictionary and I found that the chemical formula in my dictionary did not agree with the chemical formula in the wikipedia definition. My dictionary says that the chemical formula of the nitrogenous compound in urea is: CH4N2O
I'm curious Which is correct. — Preceding unsigned comment added by 209.237.14.150 (talk) 10:21, 14 April 2006 (UTC)
replies: text: CH4N2O and CON2H4 are chemical formulae, i.e. they give the number of atoms of each element in the molecule (neither is wrong), whereas (NH2)2CO gives the structural formula, which tells you how the atoms are arranged, i.e. a carbonate group attached to 2 amine groups. Tizer128 01:30, 12 May 2006 (UTC)

text: According to this website, urea is used by the skin along with epidermal lipids and proteins to keep itself moisturised and apparently "represents 7% of the natural moisturising factor in the outer layer" Tizer128 02:11, 12 May 2006 (UTC)
thread_title:  nitrogenous compound in urea 

message: Can someone provide some better Ka and Kb data? Based on Google, I have found people (1 2) saying the Kb is 1.5 x 10^{-14} --Cowbert 23:37, 25 April 2006 (UTC)
replies: text: See discussion below on pKa and pKb's.Biotechscientist (talk) 23:46, 14 July 2011 (UTC)
thread_title:  Acid/Base Equilibria 

message: I have just edited the Physiological Diagnosis subsection in the Medical Use section.... But I actually think that it should all be moved/incorporated into the blood urea nitrogen entry.  It seems to me that the Urea entry should mostly focus on the chemical urea and not on the medical/physiological issues.
I would favor having only the following line under the Physiological Diagnosis subheading:
See blood urea nitrogen ("BUN") for a commonly performed urea test, and marker of renal function. DanLevy 19:46, 14 May 2006 (UTC)
thread_title:  Physiological Diagnosis section should be removed 

message: I believe the pKa value of 0.18 for urea is incorrect; this is the value for the acylium ion of urea (a much more acidic species). The lower the pKa the more acidic. Since the pH of 10% water solution of urea is 7.2, I don't think urea is acidic(Merck Index, 12th edition). — Preceding unsigned comment added by 129.89.22.169 (talk) 17:56, 23 May 2006 (UTC)
replies: text: Fixed the pKa - this value is from Philosophical Transactions: Physical Sciences and Engineering, Vol. 345, No. 1674, The Chemistry of Biological Molecular Recognition (Oct. 15, 1993), pp. 57-66 Stijndon 11:13, 24 October 2007 (UTC)
thread_title: Incorrect pKa value

message: I do not know if urea is also produced as pills (or pellets), but the vast majority of commercially produced urea is produced as prills. Prills are prepared by letting small droplets of molten urea fall in high prilltowers. During the fall the droplets solidify, giving round particles of generally 1.4 - 2.0 mm size. — Preceding unsigned comment added by 213.84.153.69 (talk) 08:02, 9 June 2006 (UTC)
thread_title:  Prills versus pills 

message: Is it really true that urea is added to cigarettes for flavor? — Preceding unsigned comment added by 70.17.129.239 (talk) 00:29, 13 June 2006 (UTC)
replies: text: Probably not. Heat urea in a flame and ammonia is released. Not exactly the most pleasant of flavors. Just another PC bit of pseudo science, referenced from a newspaper. The best one I've seen is that cig makers add Polonium for flavor. Polonium is present in  nearly all US agricultural products, in tiny amounts. Po is in the decay chain of Radium found in North American rock fertilizer.61.68.4.208 (talk) 22:28, 17 December 2017 (UTC)
thread_title: Cigarette flavoring?

message: I was looking for scientific explanation about how and what for urea is used by microorgnisms in soil. — Preceding unsigned comment added by Merhamforal (talk • contribs) 12:15, 17 June 2006 (UTC)
thread_title:  urea in soil 

message: There is a contradiction between the entries on Sweating and Urea. I hope this is the right place to post this. This is my first comment.
The article on Sweating states that "Sweating (also called perspiration or sometimes transpiration) is the production and evaporation of a watery fluid, consisting mainly of sodium chloride (commonly known as salt) and urea in solution, that is secreted by the sweat glands in the skin of mammals."
The article on Urea states: "Many researchers used to believe that a small amount of urea was excreted (along with sodium chloride and water) in human sweat. However that was proved wrong when Dr. M. Falk determined at RC Institute that only sodium chloride and water are excreted from sweat.”
I don't know for sure which is correct but sweat either contains urea or it does not. Whoever wrote the paragraph at the article on Urea seems certain that sweat does not contain urea while the article on Sweating states that it does.
I have left this same comment at both articles on Urea and Sweating. — Preceding unsigned comment added by Mcgayhey (talk • contribs) 23:28, 29 September 2006 (UTC)
replies: text: I was going to comment on the same thing. I can't find any trace of Dr M Falk of the RC Institute. The user who added it was an anonymous user who only ever edited two articles. I question the accuracy of this information. — Preceding unsigned comment added by Zhinz (talk • contribs) 04:28, 28 October 2006 (UTC)
replies: text: Since removed. Adrian J. Hunter(talk•contribs) 09:14, 24 May 2008 (UTC)
thread_title: Contradiction (resolved)

message: Urea certainly works well on dry, cracked skin caused by severe athletes foot. I have been using a balm containing 25% urea for several days now, and there is a very noticable difference in my condition. What used to be hard, callous-like skin that was prone to cracking has now become soft, pliable, pink, and healthy looking! Masha Allaah! — Preceding unsigned comment added by 65.60.143.142 (talk) 04:44, 30 September 2006 (UTC)
thread_title: Certainly works well

message: please add information on urine urea nitrogen (a medical lab result based on protein catobilic rate). when someone types in UUN, a link should appear to this or another urea page. when someone types in urine urea nitrogen, a redirect to somewhere should appear. maybe urine urea nitrogen should be its own article or stub. — Preceding unsigned comment added by Tkjazzer (talk • contribs) 19:40, 11 October 2006 (UTC)
thread_title: Urine urea nitrogen

message: When i asked about buying urea from a company, they told me that the nitrogen it contained is over 46% (it might be the purity?!). I'm just wondering, how do they change the nitrogen content in urea? Or i've misunderstood something? tks~ — Preceding unsigned comment added by 219.80.238.184 (talk) 04:07, 16 October 2006 (UTC)
replies: text: Pure urea necessarily has only one nitrogen content (law of definite proportions). --Vuo 14:46, 24 October 2007 (UTC)
thread_title: Nitrogen content

message: Urea is the first organic compound synthetically made from an inorganic salt. It has historical significance. --Kupirijo 05:15, 1 December 2006 (UTC)
thread_title: Importance of urea

message: I don't have enough knowledge of this area to write an authoritative overview, but I feel it should be mentioned, especially as urea is a widely used fertilizer and the highest in nitrogen. Something on eutrophication of rivers, lakes and seas would be appropriate. Richard001 21:10, 30 January 2007 (UTC)
thread_title: Effect on environment

message: On H-bonds in Urea, thats why high solb. — Preceding unsigned comment added by 58.107.233.180 (talk) 15:24, 15 August 2007 (UTC)
thread_title:  NEeds section - Urea Structure 

message: Hi.  I just did a slop-job of an edit on the physiology section.  I just went there to look up a quick tidbit and it was just...strange.  So I did what I could.  I couldn't find good solid references on the web, so I'm afraid I didn't cite any, but below are a couple that are good starts (uncitable, but good explanations for the uninitiated).  Also, I'm afraid my language is a bit dense.  However, it's got to be better than what was there before, and at least I've got mad internal links.  Can't spend time on it, I'm afraid.  Here's my encouraging, "Woo-hoo!" to whoever will spend the time on it that it deserves:)  
Links that might help whoever wants to work on it:  
http://www.acbrown.com/renal/OutLoop.htm   AND 
http://www2.kumc.edu/ki/physiology/course/seven/7_4.htm  (btw, I haven't really looked through them so I'm not completely endorsing them) A0900 06:46, 30 October 2007 (UTC)
thread_title:  Physiology section--editing 

message: I believe there has been research that has shown that a high urea load is actually not in and of itself dangerous.  More to the point, I think there's been a paper that's shown that urea just SIGNALS that something else is wonky and needs to be removed from the blood (mostly likely ammonia).  I believe the experiment done was actually dumping a whole bunch of urea into pts' blood to see what would happen and answer was essentially nada.  Or maybe this is just one of those, "I heard it in rounds and it isn't actually true" things.  There are a TON of uncited "facts" on this page.  Anyone dealing with this, would you please check on this particular "fact" that someone's listed?  IF you find otherwise (i.e., that urea actually is a problem) then perhaps a mention of dialysis would be warrented? A0900 06:46, 30 October 2007 (UTC)
thread_title:  dialysis/comment on high urea load being dangerous 

message: The provided pKa and pKb values are not possible - in a water solution pKa + pKb is 14. Presently, the provided values are pKb = 13.8 and pKa = 26.9, which is logically impossible. Unfortunately I don't have any better values to add. Anyone? Annelie Skoog (talk) 19:50, 1 December 2008 (UTC)
replies: text: I can explain those values: 0,2 is the pKa of protonated urea in water, 26,9 is the pKa of urea in DMSO. Two very different things... --FK1954 (talk) 19:19, 2 March 2009 (UTC)

text: "I find that many entry level people still struggle with this even after a few college chemistry courses. Acid-Base equilibria if you can conquer it (and have good teachers) will help explain many erroneous things that occur day to day in laboratories" No kidding. I work in a soap factory doing product development and it's frustrating how often acid-base chemistry is a sticking point. I'm trying to review urea-acid salts and there is a surprising lack of info on them on the internet. I'm actually surprised there's not wiki pages for each. Urea Hydrochloride and Urea Sulfate are used in industry as alternatives to HCl and H2SO4 themselves. Does the counterion for the urea conjugate acid (urea-ium?) have an effect on the strength of the resulting salt? My gut says no, the acid is Urea-ium w/ a pKa of 0.2, and the counterion Cl- or HSO4- is "inert," having completely ionized with the Urea base (pKa of -6.3 and -2.8, respectively. HSO4- is not strong enough to protonate urea with a pKa of 2.0). Cooper Panda (talk) 14:57, 21 April 2022 (UTC)
thread_title:  pKa and pKb values for urea 

message: 70.171.235.197 (talk) 04:31, 1 July 2009 (UTC)
thread_title:  Urea Nitrate? 

message: In the ammonia page, this same problem appeared a few weeks ago, it is here, and I see that it has occurred before (top discussion topic, 2007), was corrected, and seems to have re-appeared.  The solubilities given must be off by an order of magnitude.  Is there a bot that is doing this?  Perhaps the numbers are referenced to a data table, but the units are not?  Does anyone have information on this?  Gaedheal (talk) 00:09, 25 February 2010 (UTC)
replies: text: I believe the current figures are correct.  The article currently gives figures such as 108 g/100 mL (20 °C), and has done so for a long time.  The problem with earlier versions was that the figures were ten-fold higher, such as 1080 g/100 ml (20 °C).  The lower figures are consistent with doi:10.1021/je60054a020 (requires subscription), which gives 109 g/100 mL for 21 °C, and measurements at other temperatures consistent with the Wikipedia article. That current figures also match my own personal experience: although urea takes forever to dissolve in water, it is nevertheless highly soluble, with an amount of urea dissolving in a similar amount of water at room temperature.  Adrian J. Hunter(talk•contribs) 03:00, 25 February 2010 (UTC)
thread_title:  Solubilities!!! 

message: Under "Uses":
"Urea is also used in many multi-component solid fertilizer formulations."
and then, a few sentences later:
"Urea is not compatible with other fertilizers."
They can't both be right, can they ?Eregli bob (talk) 17:39, 12 May 2010 (UTC)
thread_title:  Contradictory assertions 

message: The mp of Urea is listed as 132.7–135 °C. Having 4 significant figures in the first term and not the second doesn't make any sense. It should either read 132.7-135.0 or 133-135. I'm going to change it to the latter.  —Preceding unsigned comment added by Robertblankenship (talk • contribs) 03:35, 20 September 2010 (UTC)
thread_title:  Melting Point of Urea 

message: If my son is looking up urea on the internet do I need to be concerned that he is doing something illegal . . . like making meth?  — Preceding unsigned comment added by 24.112.120.186 (talk) 03:00, 30 May 2011 (UTC)
replies: text: I very much doubt it. Urea is a common biological substance and the most basic of starting materials; far more detailed research would be necessary to undertake such a complicated organic synthesis, and most likely your son was merely curious about the content of his urine. Furthermore, I am concerned that you suspect a family member of illegal activity due solely to their accessing this public encyclopaedia; you might consider scaling back the paranoia. Magic9mushroom (talk) 12:41, 17 July 2014 (UTC)
thread_title:  Illegal intentions?? 

message: Citation number 1 was for a search. However, this search has presumably expired long ago, and so you cannot access the information any more. Someone should remove it, and I think that whoever put it there should try to find where he got the information from, and find a better citation.
120.151.249.12 (talk) 21:03, 19 April 2012 (UTC)
thread_title:  Out of Date Citation 

message: I removed the side remark from the introduction that urea produces ammonia in the presence of water or water vapor, as I believe this reaction does not occur spontaneously to a significant degree at room temperature, without a catalyst such as the enzyme urease produced by many soil microorganisms.  It is for this reason that urease inhibitors are sometimes added to urea fertilizer.  See article on ammonia volatilization from urea.  I think discussions of conditions under which urea undergoes hydrolysis, and ways of catalyzing or inhibiting it, might be appropriate elsewhere in the article, but are too specialized for the introduction. CharlesHBennett (talk) 14:23, 18 April 2013 (UTC)
thread_title:  spontaneous hydrolysis? 

message: Given the Wohler reaction, ammonium cyanate should probably redirect to this page, but I'm not savvy enough to make a redirect. Could someone help out? Magic9mushroom (talk) 12:41, 17 July 2014 (UTC)
thread_title: Ammonium cyanate as a redirect?

message: Substituted at 09:44, 30 April 2016 (UTC)
thread_title: Assessment comment

message: "It forms ions and salts known as ureates." should be added, I think, but the only source I could find is
https://nl.wikipedia.org/wiki/zouten "het ureaat-ion".
Formula: (NH3)2CO2+
Simon de Danser (talk) 20:44, 25 November 2020 (UTC)
thread_title: Ureate

message: As of 20220203, the three displayed structures are not equivalent. The line drawing is C2H4N2O, while the two 3d drawings and correct formula are CH4N2O. 178.200.120.156 (talk) 20:28, 3 February 2022 (UTC)
thread_title: Incorrect structure image

message: In the Agriculture sub-section of Uses, at the very end, there is the following quote: "Another technology is the conversion of urea into derivatives, such as formaldehyde, which degrades into ammonia at a pace matching plants' nutritional requirements." I feel like this could use a bit of cleaning up, as if urea is converted into formaldehyde, which contains no nitrogen, it cannot degrade into ammonia, which does contain nitrogen. It's possible this is talking about some sort of salt of urea and formaldehyde, or some other side reaction that happens in the soil to add nitrogen to formaldehyde, or possibly about the process of cleaving urea into ammonia and formaldehyde, but I'm not familiar enough with the chemistry of this to make corrections. As it is, it doesn't sound correct. Lumberjane Lilly (talk) 21:17, 3 June 2022 (UTC)
thread_title:  Clarity needed in first paragraph of Uses section 

message: The third paragraph of the first section of the article says that urea is "neither acidic nor alkaline", but in the Properties/Reaction section, it says that urea is basic. Which is it, please? Cladist (talk) 23:37, 29 August 2023 (UTC)
thread_title:  Contradiction: Is urea basic? 

message: according to VSEPR theory, should the nitrogen in urea be trigonal pyramaidal? 67.160.97.30 (talk) 01:30, 15 December 2023 (UTC)
replies: text: Good observation. I updated the article: it's planar in solid because of sp2 hybridiaztion of the N, and somewhat closer to trigonal pyramidal in gas or solution. –MadeOfAtoms (talk) 02:19, 16 December 2023 (UTC)
thread_title:  possible error