Talk:Calcium hydroxide

message: The values of Ksp and solubility do not get along. They are related by Ksp=4x^3 or x=(Ksp/4)^(1/3)
If Ksp=4.68 you get 1.05E-2 M or 0.6145 g/L or 0.06145 g/100 mL.
This is much less than the smallest of all numbers given.
Other sources, e.g.
http://www.ktf-split.hr/periodni/en/abc/kpt.html
show Ksp=5.02E-6, producing 1.079E-2 M or 0.6291 g/L or 0.06291 g/100 mL.
Alternatively, if you use 0.173 g/100mL or 1.73 g/L you get 0.02338 M (Ca(OH)2 saturated concentration, or Ksp=5.11E-5  — Preceding unsigned comment added by 50.193.173.17 (talk) 20:44, 26 September 2012 (UTC)
thread_title: Ksp

message: There is no mention under industrial applications of wet scrubbing flue gas desulfurization. Granted, Calcium Hydroxide is not the initial principle reagant for that, CaO is, but by the time the flue gas comes in contact with the sorbent, it is Calcium Hydroxide.Woahmid (talk) 00:09, 29 February 2012 (UTC)
thread_title: Flue Gas Desulfurization

message: Lutefisk literally translates as "lye fish" so someone should check if it's lime or lye that is used.  —Preceding unsigned comment added by 174.91.183.133 (talk) 02:21, 5 December 2010 (UTC)
thread_title: Lutefisk

message: The impression you get from reading the hazards is that this stuff is dangerously toxic, it is not, however. I think this should be changed. 194.53.253.51 (talk) 08:15, 22 April 2009 (UTC)
thread_title: hazards

message: True - not especially toxic - but can cause very bad burns - and while an acid burn hurts right away - if you get some in your shoe - with a little sweat or moisture it will feel slightly uncomfortable while it digests your skin - (Found out the hard way - removed my socks to find skin missing and  bleeding - took a month to heal.) .  — Preceding unsigned comment added by 108.243.106.82 (talk) 15:14, 1 April 2015 (UTC)
thread_title:  Can cause bad burns 

message: There should be separate articles for slaked lime, lime water, milk of lime and common applications, and Calcium hydroxide, Magnesium hydroxide with Chemistry etc.  Same goes for Calcium Oxide / lime (mineral).  Comments please PeterGrecian 14:26, 19 Apr 2005 (UTC)
replies: text: I disagree with this proposal.  Put your effort into fleshing out this article and cleaning it up, as the tag asks us to.  In the unlikely event that this one gets unwieldy, something could later be split out.  Gene Nygaard 18:52, 6 October 2005 (UTC)
thread_title: article division

message: I agree with your comments. Also... the formatting of the article is poor with lines chopped in two. Perhaps it has been copied from somewhere - and there are copywrite issues? Also what on earth is polikar! It looks like something Russian? CustardJack 16:55, 11 May 2005 (UTC)
thread_title:  clean up. 

message: I have tried to cleanup the grammar and style problems, although a few clunky bits remain. In particular, I was unsure as to whether to change the word "drug" to "chemical" or "preservative" in the last line of the "Uses" section. Also, the line "Because of its strong basic properties, calcium hydroxide has many varied uses as:"
is very cumbersome and should be edited further. I also believe the phrase "but unrelated to the citrus fruit (lime)" should be removed and a link to a lime disambiguafication page placed at the top of the article, but I'm running out of time for editing right now.
-Paul Foster 9:08, 23 May 2005 (EST)
One question: As to the dangers through overdose section, can't the difficulty breathing and internal bleeding be explained by the hypotension?
- Guest 4:09, 3 Feb 2007 (Pacific Time)
The article states: "When heated to 512 °C, the partial pressure of water in equilibrium with calcium hydroxide reaches 101 kPa and decomposes into calcium oxide and water."  This sentence needs to be edited, but since I don't have access to the reference, I can't do it.  As this sentence reads now, the partial pressure of water decomposes into calcium oxide and water, which is nonsensical.  Partial pressures don't decompose.    —Preceding unsigned comment added by 75.26.143.229 (talk) 23:29, 27 May 2010 (UTC)
replies: text: Tweaked. Materialscientist (talk) 23:34, 27 May 2010 (UTC)
thread_title:  further cleanup 

message: Are their any methods of production that are cheap and don't produce CO2 Ozone 19:16, 28 February 2006 (UTC)
replies: text: There are expensive methods, which does not produces CO2 (but produces SO2). Starting material there would be calcium sulfate. SO2 is worse for environment than CO2, and in such case it could not be filtered, because the cheapest material for removing SO2 from waste gas stream is calcium hydroxide itself. -Yyy (talk) 07:55, 2 March 2008 (UTC)
thread_title:  Production 

message: There might be some argument for merging Portlandite (which is the crystalline mineral) into this, but not vice versa.  Its crystalline mineral nature is just one of many attributes of calcium hydroxide. . . . LinguisticDemographer 13:45, 17 March 2007 (UTC)
thread_title: Merger with Portlandite

message: Now, I've heard that the celts washed their hair with slaked lime, or Calcium hydroxide, and so made it stiff and, also, bleached it. However, I'm struggling to find out if you can actually do this with lime alone, or if there were other ingredients involved, or what?
The details, unfortuantely, are not particularly thick on the ground. Here's a couple of links with most of what I know -
http://www.celticcoins.com/pages/131106.html
' "Their hair is blond, and not only naturally so, but they also make it their practice by artificial means to increase the distinguishing colour which nature has given it. For they are always washing their hair in lime-water, and they pull it back from the forehead to the top of the head and back to the nape of the neck with the result that their appearance is like that of Satyrs and Pans, since the treatment of their hair makes it so heavy and coarse that it differs in no respect from the mane of horses" '
http://www.123freehost.co.uk/sites/adam7daviesessays/
' The Celts bleached and spiked their hair with lime – one ancient writer wrote that each spike of hair was so sharp that an apple could be impaled on one! '
- I'd be very interested in knowing more about this, if anyone has the time to research it more deeply than I have.
41.243.78.15 15:15, 16 May 2007 (UTC)
thread_title:  Celts and hair 

message: One paragraph says Ca(OH)2 decomposes at 512 C, and the chembox at right says 580 C. Which is it? 97.82.247.200 10:02, 11 August 2007 (UTC)
thread_title:  Decomposition 

message: In the intro there is a footnote that claims that 512°C is the temperature at which H2O vapor pressure reaches 101 kPa.  What on earth is meant here?  At 100°C the vapor pressure of water reaches 101 kPa and it boils.  Maybe this is meant to refer to the partial pressure of H2O over Ca(OH)2? --Slashme (talk) 10:22, 21 January 2008 (UTC)
replies: text: Yes, it must be the partial pressure of H2O in the equilibrium Ca(OH)2 -> CaO + H2O(g). --Itub (talk) 13:02, 21 January 2008 (UTC)
thread_title:  Vapor pressure 

message: Is it possible to make by reaction with sea water, instead of pure water? If so, what additional substances would be made. 86.30.179.100 (talk) 18:17, 15 November 2009 (UTC)
thread_title:  sea water 

message: What happens if metal comes into contact with slaked lime?199.33.32.40 (talk) 02:46, 11 August 2010 (UTC)
replies: text: The result depends on the metal, but for most commonly encountered metals, nothing would happen rapidly.  In contact with base (such as Ca(OH)2) and water, most metals corrode to the oxides.--Smokefoot (talk) 14:19, 18 September 2010 (UTC)
thread_title: Metal and slaked lime

message: I'd like to see a cite about lutefisk made with calcium hydroxide, as opposed to lye.  I'm skeptical that calcium hydroxide would even work.  Francis Lima (talk) 21:31, 19 September 2010 (UTC)
thread_title: Lutefisk?  Really?

message: I've read a lot about the use of lime for mass graves of plague victims, and have just been reading about the mass graves in the Holocaust. Nothing is mentioned of this usage here and I don't know enough about it to comment (or whether this is the right page!) - any help would be great. Jess xx (talk) 22:12, 19 June 2011 (UTC)
thread_title: Use in Mass Graves

message: So ... It has a level 3 for health, but "has many practical uses, including food"? uh .... can someone explain/correct this? UNIT A4B1 (talk) 23:47, 30 November 2011 (UTC)
replies: text: according to this site http://www.jainworld.com/jainfood/silverfoil.asp it is not suitable for use in paan because it is made from the shells of living animals.--Richardson mcphillips (talk) 17:49, 13 January 2014 (UTC)
thread_title:  use in food 

message: Under 'Niche Uses", the bulleting is tabbed in under Calcium stearate, so it appears that the following 8 bullets pertain to Calcium stearate. I have checked 4 of the items and they are still seem to be referring to Ca(OH)2. (Neither Ca stearate or Ca hydroxide is mentioned in brake pad or Ebonite wiki entries?).  I was interested in the use of Ca hydroxide as an pesticide and had to check to see if it was in fact the stearate or hydroxide being referred to.
This is my first entry on Wiki, so can someone else review and/or edit if necessary? Cornyvet (talk) 04:10, 22 April 2012 (UTC)
thread_title:  Niche uses: Bulleting under Calcium Stearate 

message: I am trying to find a source for the slaked lime used to make gesso and it would be helpful to know if food grade calcium hydroxide is used for traditional gesso -- often called gesso sotile.  It isn't mentioned in the many uses discussed on this page, but if it is the same thing, then it would make my search for a source very easy and it would also be useful to be included on the page in case other gilders or tempera artists are also looking.  I was hoping that someone would know.
Pbfasks (talk) 16:51, 25 April 2012 (UTC)
thread_title:  calcium hydroxide -- slaked lime:  gesso? 

message: This article is dysfunctional or semi-functional at best.  Can someone please take it upon themselves to do a rewrite (from scratch)?  — Preceding unsigned comment added by Gibson88 (talk • contribs) 12:49, 3 June 2014 (UTC)
thread_title:  Rewrite this entire article 

message: It seems to me that the caption for the two types of corn kernels is reversed. The white ones have been treated and the yellow ones have not. The page on hominy has it right.
- Metricator  — Preceding unsigned comment added by Metricator (talk • contribs) 01:04, 6 April 2015 (UTC)
thread_title:  Picture caption 

message: pKb values in article are invalid and non-verifiable, due to the fact the referred content is not an original research neither gives any further references.
IUPAC buffers suggests for a saturated Ca(OH)2 solution at 25°C ph=12.45 - http://www.ph-meter.info/pH-electrode-calibration-buffers
By making approximation that Ca(OH)2 dissociated only once in the solution and concentration of calcium hydroxide ion [Ca(OH)+] approximately equals to concentration of hydroxide ion [HO-] ( Ca(OH)2 <=> Ca(OH)+ + HO- ), we can see that:
Water self ionization at 25°C Kw = [HO-][H+] = 1.0×10-14 (1) , logKw = 14.0 - https://en.wikipedia.org/wiki/Self-ionization_of_water ;
Kb = [Ca(OH)+]×[HO-] / [Ca(OH)2] ;
Provided concentration of calcium hydroxide ion [Ca(OH)+] approximately equals to concentration of hydroxide ion [HO-] ( due to  Ca(OH)2 <=> Ca(OH)+ + HO- ), we get Kb = [HO-]2 / [Ca(OH)2] (2)
Combining the two equations (1) and (2) we can derrive the Kb values from [H+]:
Kb = (Kw/[H+])2 / [Ca(OH)2]
pKb = -log Kb , pKw = - log Kw, solubility of Ca(OH)2 at 25°C is approximately 1.67 g/L, yielding molar solubility of 22.5×10-6 mol/L, and pCa(OH)2 = -log[Ca(OH)2] = 4.65
Substituting the values with their negative logarithms we get:
pKb = (pKw - pH) × 2 - pCa(OH)2 = (14.0 - 12.45) × 2 - 4.65 = - 1.55
This value is not a first dissociation constant of calcium hydroxide (pKb1), it is lower than pKb1 due to the fact that second dissociation happens and because concentration of hydroxide ion is not equal to the concentration of calcium monohydroxide ion. Anticipated values of the first dissociation constant pKb1 for calcium hydroxide is in the range of -1.0..0.5, but measurements in this range are complicated and values vary from source to source.
IUPAC publication Dissociation Constants of Inorganic Acids and Bases in Aqueous Solution (1969) at p. 151-152 provides a collection of the references for different measurements of pKb values for Ca(OH)+ ion, with most values in the range of 1.02..1.51.
I'm going to edit the article and incorporate the final numbers and references into the article. 193.110.114.207 (talk) 03:18, 17 June 2017 (UTC)
thread_title:  pKb 

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thread_title:  External links modified 

message: Since the issue here seems a little difficult to grasp for certain people: a) "reliable sources" does not include a crowdsourced homework help page. b) Even if this were a defensible statement, the lede is there to summarize article content, not add new material. You either treat this in the body, at a length that then justifies inclusion in the lede, or you leave it out entirely.
Stupid posturing is not a suitable replacement for addressing these issues, . And if I continue to see you revenge-revert my edits in other articles, you've got some exercise coming.--Elmidae (talk · contribs) 13:25, 27 August 2018 (UTC)
thread_title:  CO2 absorption 

message: This article is cited many times
*
: .... 0mtwb9gd5wx (talk) 15:44, 12 May 2023 (UTC)
thread_title: Further reading

message: The following was removed from the article:
Where is this from? No citation. -->According to Hopkins and Wulff (1965), the decrease of calcium hydroxide solubility with temperature was known since the works of Marcellin Berthelot (1875)Berthelot, M. (1875). Dissolution des acides et des alcalis. [Dissolution of acids and alkalis]. In: Annales de Chimie et de Physique. Vol. 4, pp. 445–536. and Julius Thomsen (1883)Thomsen J. (1883). Thermochemische untersuchungen [Thermochemical studies]. Vol. III, Johann Ambrosius Barth Verlag, Leipzig. (see Thomsen–Berthelot principle), when the presence of ions in aqueous solutions was still questioned. Since, it has been studied in detail by many authors, a.o., Miller and Witt (1929) or Johnston and Grove (1931) and refined many times (e.g., Greenberg and Copeland (1960); Hopkins and Wulff (1965); Seewald and Seyfried (1991); Duchesne and Reardon (1995)).
The reason for this rather uncommon behavior is that the dissolution of calcium hydroxide in water involves an entropy decrease, due to the ordering of water molecules around the doubly charged calcium ion, This counter-intuitive temperature dependence of the solubility is referred to as "retrograde" or "inverse" solubility. The variably hydrated phases of calcium sulfate (gypsum, bassanite and anhydrite) also exhibit a slight retrograde solubility due to the presence of the calcium ion. However, other calcium salts like calcium chloride show an increase in solubility since the enthalpy change is larger and dominates the free energy change during dissolution. In all cases, the dissolution is exothermic.
--Smokefoot (talk) 20:35, 4 June 2024 (UTC)
thread_title: Retrograde solubility

message: I propose to merge limewater into calcium hydroxide.  The only content that is not overlapping directly is the structure of solid Ca(OH)2.  All behavior of limewater is the chemistry of calcium hydroxide. But maybe I am missing some counter argument. --Smokefoot (talk) 23:06, 4 June 2024 (UTC)
thread_title: Merge proposal