Talk:Potassium hydroxide

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Contents 1 Inconsistency with NaOH 2 Melting Point 3 Melting point thought: 4 Improvements 5 Carbon Dioxide absorbant 6 Food section 7 Basicity

[edit] Inconsistency with NaOH

Both this page and the NaOH say their compound is more commonly used for biodiesel because it does not clump as much. They can't both be right.

[edit] Melting Point

A wider search of the net shows some variety of figures for the melting point of KOH. ONe manufacturer quotes 360C, and another source quotes 380C. The Wikipedia article quotes 406C.

Anyone any ideas which is correct, or where there is an authoritative source.

Na+ and K+ are very similar chemically speaking, so perhaps the tendancy not to clump is in contrast to divalent ions like Ca++. --[1]

[edit] Melting point thought:

You may want to try the Handbook of Chemistry and Physics.

> The physical constants have been updated with their "CRC Handbook of Chemistry and Physics 2006" values

Reply: the melting point is indead 380 degrees. this is taken for the as chenistry revision guide and for exan pruposes this has to be correct

You have wonderful faith in the people who set exams (of whom I am one)! One problem with the measurement of the melting point of KOH is that it is pretty much never anhydrous: there is always some water associated with it, even as a melt. The more water, the lower the melting point (as for almost all mixtures). The melting point may also vary with the rate of heating and other experimental parameters. The only reason that a melting point is quoted at all is to show that KOH melts before it dehydrates to K₂O. Physchim62 (talk) 10:14, 6 April 2007 (UTC)

[edit] Improvements

I've begun efforts to bring this article into accordance with the Wikipedia:Manual of Style.--YanA 00:26, 23 April 2007 (UTC)

Sorry, I couldn't find where to make a new category for discussion but I just wanted to ask two questions. Is Potassium Hydroxide will react with Methanol? And What is the maximum solubility of Potassium Hydroxide in Methanol? —Preceding unsigned comment added by Marksiqi (talk • contribs) 07:14, 10 May 2008 (UTC)

[edit] Carbon Dioxide absorbant

In several novels, such as From the Earth to the Moon, and several non-fiction books, such as Blind Man's Bluff, crystals of caustic potash are used to remove carbon dioxide from the air in confined spaces. Is this accurate? If so, then by what process?RSido 19:42, 29 April 2007 (UTC)

Yes, after a bit of poking around, potassium hydroxide and for that matter many other things containing hydroxide ions can absorb CO₂. You may want to check out this paper: Kucka, L.; Kenig, E. Y.; Górak, A Ind. Eng. Chem. Res. 2002, 41, 5952-5957. It doesn't go into the details about how it happens to much but it shows that KOH(aq) does indeed absorb CO₂. They don't say much about the solid. --YanA 04:25, 2 May 2007 (UTC)

All alcali hydroxides are good absorbents of CO₂, the reaction beeing: 2M^+IOH^–_(s) + CO_2(g) → M^+I₂CO₃·H₂O_(s), forming the corresponding alcali carbonate monohydrate; however, in most applications (e.g. submarines and space modules), lithium hydroxide, LiOH is used for this purpose, because of two properties:

1. Lithium has the lowest atomic mass of all alcali metals, resulting in LiOH having a molecular mass of only about 24; that's 58% of M of sodium hydroxide and only 41% of M of potassium hydroxide. This means, that, e.g. for absorbing/binding 1 kg of CO₂, you need only about 1.1 kg of LiOH, instead of about 1.82 kg NaOH or 2.55 kg KOH, making the lithium hydroxide the most volume-effective alternative (meaning, that you need less than half of mass and volume of sodium hydroxide to bind equivalent amount of carbon dioxide, which is place-sparing and, in space technlogy, fuel-sparing).

2. LiOH is the least hygroscopic of all alcali hydroxides; while NaOH and KOH rapidly absorb air moisture, "caking" together and eventualy dissolving into lye, lithium hydroxide rests solid and thus, is easier to process into compact batteries for the use.--84.163.122.90 04:44, 28 October 2007 (UTC)

Added a lot of sources, but didnt sign in heh. Xeolyte 22:57, 16 October 2007 (UTC)

[edit] Food section

I believe the food section is referring to uses of common lye (sodium hydroxide), not Potassium hydroxide. This section should be deleted or moved. --Superbeecat 05:56, 29 June 2007 (UTC)

Both sodium and potassium hydroxides are used, sodium hydroxide prevalently, though. Sometimes, even mixtures of both are used. However, potassium hydroxide is a relevant food industry chemical.--84.163.122.90 04:23, 28 October 2007 (UTC)

[edit] Basicity

Add basicity to properties box, as per Caesium hydroxide. —DIV (128.250.80.15 (talk) 04:04, 4 March 2008 (UTC))