Talk:Magnesium hydroxide

Removed

removed this chunk of text, source is unverifiable,

"Milk of magnesia is also used as a folk remedy, applied and massaged into the scalp a few minutes before washing, to relieve symptoms of seborrhea and dandruff. The mechanism for its effectiveness in this application, like the causes of seborrhea itself, are unknown. An additional folk use is for the treatment of acne or oily skin by applying topically, allowing to dry, and then washing it off the face (or other body part). It is also said to be used for seborrheic dermatitis, which is a drying and flaking of the skin similar to dandruff but often occurring on the face." — Preceding unsigned comment added by Flairmonkey (talk • contribs) 16:47, 30 September 2013 (UTC)

30/09/13 user:Flairmonkey

may need help?

I added the extra use for magnesium hydroxide (biorock) if somethings wrong with that just let me know. ToddSweeney (talk) 17:52, 13 June 2008 (UTC)

Needs TOC

Someone vandalized the uses part of this page sometime before 9/30/2011. — Preceding unsigned comment added by 130.91.64.16 (talk) 18:19, 30 September 2011 (UTC)

This page may need a TOCNtlhui (talk) 22:38, 4 October 2009 (UTC)

Ksp, and solubility

My chemistry textbook gives Ksp of 2.06 x 10^-12 Is there a reason my textbook would be different than this page? — Preceding unsigned comment added by TreboniusArtorius (talk • contribs) 04:02, 8 May 2012 (UTC)

You can find other values:

http://www.ktf-split.hr/periodni/en/abc/kpt.html

presents Ksp=5.61E-12 — Preceding unsigned comment added by 50.193.173.17 (talk) 19:38, 26 September 2012 (UTC)

May be, at different temperatures, or may be, it was corrected at one time.

More important, however, is that solubility in water (was 0.12 g in 100 mL) is wrong:

must be orders of magnitude lower than the solubility of Ca(OH)2. Assuming Ksp is/are correct:

Using the formula Ksp=4x^3, and Ksp=1.5E-11 you get x = (Ksp/4)^(1/3) or 1.56E-4 M or 0.0091 g/L or 0.00091 g/100 mL.

If Ksp=2.06E-12 you get 8.02E-5 M or 0.0047 g/L or 0.00047 g/100 mL.

The reason is, that Ca(OH)2 has 0.173 g/100mL at 20 degC, and it is well known that Mg(OH)2 is MUCH less soluble.

If you use the value of either 1.5E-11 or 2.06e-12, take a cubic root, you get smtg like 2.47e-4 (or less). Then, multiply this by MW of 58 and you got 0.00144 g/100 mL (or less if you use 2.06E-12). — Preceding unsigned comment added by 50.193.173.17 (talk) 21:09, 25 September 2012 (UTC)

The 52nd edition of the CRC handbook gives solubility as 0.0009 g/100 ml.Eaberry (talk) 02:40, 21 July 2013 (UTC)

Active species for laxative effect

"hydroxide ions themselves do not play a significant role in the laxative effects of milk of magnesia, as basic solutions (i.e., solutions of hydroxide ions) are not strongly laxative, and non-basic Mg2 solutions, like MgSO4, are equally strong laxatives mole for mole" - After it has passed through the acidic stomach it is likely that all the OH- has been neutralized and the solution contains (highly soluble) Mg(Cl)2. You might say the insoluble slurry of Mg(OH)2 is a more palatable way to deposit high concentrations of Mg(Cl)2 in the intestine.Eaberry (talk) 02:40, 21 July 2013 (UTC)

Assessment comment

The comment(s) below were originally left at Talk:Magnesium hydroxide/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Milk of magnesium is a common name and not used in the international scope. magnesium hydroxide is a more internationally recognised term and agreed on by nomenclature. use milk of magnesia as a alias to the real chemical name, magnesium hydroxide, rather than visa versa I agree with these comments. Milk of magnesia is also a suspension, and not a chemical compound per se. Londen60 20:36, 8 June 2007 (UTC)

Last edited at 20:36, 8 June 2007 (UTC). Substituted at 22:49, 29 April 2016 (UTC)

Basicity pKb = 2.6 ?

The infobox says Basicity (pKb) 2.6. What does this mean please? For a Bronsted base such as an amine, pKb = -log Kb = -log[BH ][OH^-]/[B]. But this makes no sense for B = Mg(OH)₂ which is a solid and does not protonate to form Mg(OH)(OH₂) . Nor does it make sense for the OH^- ions produced by the dissolution of Mg(OH)₂, since by the definition, K_b(OH^-) = [H₂O][OH^-]/[OH^-] = 55 M so that pK_b = -1.7. So what does the number 2.6 represent please, and also where does it come from. I am adding a citation needed tag, as perhaps with a source we can see what is meant. Dirac66 (talk) 01:46, 12 December 2016 (UTC)

Maybe we should remove the pKa bit if no one responds in a while. Articles with a lot of medicinal implications can be flakey. It also states (and maybe I repeated) that the layers between the Mg(OH)₂ slabs are held together by hydrogen bonds but mu-OH is a H-bond donor, I dont see any H-bond acceptors. A lot of work has been done on doping brucite with other metals. --Smokefoot (talk) 13:40, 12 December 2016 (UTC)

Medicinal implications? If you mean the link to Try milk of magnesia for pesk acne which was at the bottom of this page, that actually belonged to the old comment Removed at the top of the page. It was at the bottom because the old comment did not have a Reflist parameter, so I have inserted one which moved the comment where it belongs. It had nothing to do with this discussion.

Anyway I agree with removing the pKb value from this article if no one responds in a while. And also from the page on Ca(OH)₂. Dirac66 (talk) 00:00, 13 December 2016 (UTC)

I have now found one reference [here] which defines K_b for metal hydroxides as for the Arrhenius-type dissociation Mg(OH)₂ = Mg(OH)^- OH^-. This could explain the value given, but I am uncertain whether this is a reliable source and a widely accepted definition. So I have moved the discussion to Talk:Acid dissociation constant, since it is a question of the definition and not restricted to Mg(OH)₂. Dirac66 (talk) 22:22, 17 December 2016 (UTC)

Odd reference to GSK

This paragraph seems like a non-sequitur to me, and I wonder what the point is of the reference to GSK:

Although the name may at some point have been owned by GlaxoSmithKline, USPTO registrations show "Milk of Magnesia" and "Phillips' Milk of Magnesia" have both been assigned to Bayer since 1995.

GSK isn't even referenced at the citation at https://tsdr.uspto.gov/#caseNumber=70024049&caseType=SERIAL_NO&searchType=statusSearch , so there's no evidence that GSK has ever had anything to do with this product. I might as well edit this to read, "Although the name may at some point have been owned by Craig from Wikipedia ...".

Shouldn't this paragraph just read:

USPTO registrations show "Milk of Magnesia" and "Phillips' Milk of Magnesia" have both been assigned to Bayer since 1995.

Absolutely no need for the introduction involving an unrelated entity.

--Craig (t|c) 08:19, 11 November 2022 (UTC)

I fixed this. --Craig (t|c) 23:17, 17 November 2022 (UTC)

source of all magnesium metal?

Does the relatively easy extraction of Magnesium hydroxide from seawater imply that this is te main source of magnesium metal after further processing? Fsikkema (talk) 14:10, 20 April 2023 (UTC)