Talk:Calcium hydroxide

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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. 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 (talk) 20:44, 26 September 2012 (UTC)

Flue Gas Desulfurization[edit]

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)


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


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. (talk) 08:15, 22 April 2009 (UTC)

Error Redirect[edit]

I wrote in Calcium Hydrate, and was redirected to Calcium Hydroxide. These are not the same thing. Calcium Hydrate is Ca·6H2O [or Ca(aq)] (i believe - I actually came to check the number of water molecules per calcium ion), while Calcium Hydroxide is Ca(OH)2. I would stop the redirect, but I don't know how. :( - Baribeau 01:38, 27 November 2006 (UTC)

Ca.6H2O exists only in solution. If you dissolve CaCl2 in water, you'll probably get Ca2+ . xH2O. But in solid form, the only thing that you can get is the hydroxide, probably with a lot of water in the crystal structure.

article division[edit]

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)

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)
  • There are identical articles for calcium hydroxide, slaked lime and hydrated lime. Is triplication necessary or just a waste of reading time, not to mention confusing? GGBiscuit (talk) 20:22, 1 September 2013 (UTC)

clean up.[edit]

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)

further cleanup[edit]

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 (talk) 23:29, 27 May 2010 (UTC)

Tweaked. Materialscientist (talk) 23:34, 27 May 2010 (UTC)


Are their any methods of production that are cheap and don't produce CO2 Ozone 19:16, 28 February 2006 (UTC)

No!! . . . LinguisticDemographer 13:39, 17 March 2007 (UTC)

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)


would it be possible to add an shortcut for Ca(OH)2?because not everybody looks for Calcium Oxide...

Merger with Portlandite[edit]

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)

Celts and hair[edit]

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 -

' "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" '

' 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. 15:15, 16 May 2007 (UTC)


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

Vapor pressure[edit]

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)

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)

sea water[edit]

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

Metal and slaked lime[edit]

What happens if metal comes into contact with slaked lime? (talk) 02:46, 11 August 2010 (UTC)

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)

Lutefisk? Really?[edit]

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)

Use in Mass Graves[edit]

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)

use in food[edit]

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)

according to this site 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)

Niche uses: Bulleting under Calcium Stearate[edit]

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)

calcium hydroxide -- slaked lime: gesso?[edit]

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)

Rewrite this entire article[edit]

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 (talkcontribs) 12:49, 3 June 2014 (UTC)