Talk:Carbonate

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Chemistry (Rated Start-class, High-importance)
WikiProject icon This article is within the scope of WikiProject Chemistry, a collaborative effort to improve the coverage of chemistry on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 High  This article has been rated as High-importance on the project's importance scale.
 

This article has comments here.


Untitled[edit]

I'm a bit confused with nomenclature here, maybe a naive thought but at least something is missing.

If the protonated species is carbonic acid (=carbonate), and HCO3- is bicarbonate, should the deprotonated species not be tricarbonate. Silly question maybe, but I went googling with tricarbonate and found some hits in minerals.

E.g. Lead sulphato-tricarbonate (synonymous to Leadhillite) is Pb4SO4(CO3)2(OH)

So what is tricarbonate?

Don't rightly know about tricarbonate. But the problem with the bicarbonate is one of nomenclature. The old name for HCO32- was bicarbonate as used in sodium bicarbonate. the bi in this case stood for hydrogen. The nomencalture is outdated, but still in common use. Also used in sodium bisulfate, etc. The currently accepted name is sodium hydrogen carbonate.
OK, did some googling. the archaic name for leadhillite was once in use (also see there is an error in that wiki article). A more modern meaning is from the rare mineral rubidium grimselite, Rb6Na2[(UO2)(CO3)3]2·H2O in which there are three carbonate ions - logical terminology, but no relation to bicarbonate. Hope all this helps :-) Vsmith 23:35, 19 September 2005 (UTC)

Class[edit]

Thought I'd upgrade this to start class, it certainly isn't a stub anymore. Welldone to everyone who has worked on it. Terri G 18:12, 24 August 2006 (UTC)

Move comment[edit]

CarbonateBicarbonate   (Discuss)
There is already a separate page for Bicarbonate, but Carbonate and Bicarbonate are the same chemical. Both pages have information excluded from the other. The chemical is usually referred to as Bicarbonate, although either is acceptable. — 15:02, 29 September 2006 (UTC)JsbosoxJSBoSox
moved from article page --mervyn 18:48, 29 September 2006 (UTC)
this is completely wrong. --Spoon! 11:19, 5 March 2007 (UTC)


Sorry a bicarbonate is different than a carbonate. They are related however. In acid base chemistry carbonates will form bicarbonates in solution.
CO3,-2 + 2 H2O <> HCO3-1 + OH- + H2O <> H2CO3 + 2 OH-.
and of course when at carbonic acid
H2CO3 <> H20 + CO2
A bicarbonate is an amphiprotic ion where it can act as an acid or a base. When in solution with acids it will accept a proton and in this case it acts like a base, but at the same time when it is around hydroxides it can act like an acid. Carbonates are strictly bases. LoyalSoldier 04:49, 21 March 2007 (UTC)

Ocean acidification[edit]

Please do not put this under the carbonate ion. It has nothing to do with it. Ocean acidification has to do with carbonic acid and carbon dioxide which will form carbonates, but the ion is not responsible for the acidification. If you put it under Carbon dioxide and carbonic acid it would make more sense because by the time it is at a carbonate it is a base. LoyalSoldier 06:18, 24 March 2007 (UTC)

Sodium Bicarbonate[edit]

I have moved the link for Sodium Bicarbonate over to the page for the Bicarbonate ion. LoyalSoldier 06:22, 24 March 2007 (UTC)

Conjugate acid-base[edit]

Conjugate acid of a weak base is a strong acid, so the following

The carbonate ion is a weak base. This is because it is a conjugate base of a weak acid. As such the carbonate ion seeks to reclaim hydrogen atoms.

should read

The carbonate ion is a strong base. This is because it is a conjugate base of a weak acid. As such the carbonate ion seeks to reclaim hydrogen atoms.


If anyone else agrees with this, please fix. If noone disagrees in a couple of days, I'll do it myself.Aurimas 02:56, 19 September 2007 (UTC)

I am sorry, but that is completely wrong. A weak acid can produce a weak base and this is the exact case of that. A strong acid will produce such a weak base that it can hardly even be called a base. I this case both Carbonic Acid and Carbonate ion are both weak(Aka do not completely donate/receive hydrogen ions). By definition a strong acid completely ionizes (or to such a point you can not measure unionized particals) in solution. LoyalSoldier 04:35, 24 September 2007 (UTC)
You are correct. I'm not sure what I was thinking. Sorry about the confusion. Aurimas 15:25, 27 September 2007 (UTC)
No, no Loyal Soldier, it is I who am sorry, for carbonate is indeed a strong base. The conjugate base of a weak acid is strong. It will readily take back the protons its conjugate acid unwillingly gave up in the first place. Think hydroxide, OH- protonates to H2O. Not a very strong acid. And oxygen. The fact that all stuff gets old is usually due to this. And that's with no hydrogens. Very basic indeed.

By definition a strong acid completely ionizes (or to such a point you can not measure unionized particals) in solution. This is a particularly weak starting point as far as the conjugate/deprotonated base is concerned. 10 foot barge pole is as close as any hydrogen's likely to get until conditions change.Menswear 17:35, 5 October 2007 (UTC)

It is not a strong base because the reverse reaction is very much possible. You can add acid to carbonates to get carbonic acid and you can add a base to carbonic acid to get carbonate. By that definition alone it is a weak base because the chemical equilibrium is not shifted so far to one side that it is near impossible to reverse the reaction. Now it can be relatively strong on the pH scale(Which actually a 6M solution only has a pH of about 10.6), but it is not a strong base. A weak acid can produce a weak base. The strength of the base is inverse to the acid. In titrations with carbonates you are often told to move the reaction to the desired pH range and then heat your mixture slightly because the carbonic acid that has formed with mess with your results. Also I might add that if it was not a weak base then a buffer system which your body uses would be impossible.LoyalSoldier 05:10, 20 October 2007 (UTC)

History[edit]

The current version of this article (http://en.wikipedia.org/w/index.php?title=Carbonate&oldid=266181425) says that "It is generally thought that the presence of carbonates in rock is unchallengable evidence for the presence of liquid water." This seems misleading. Think of calcite in marbles, and carbonatite lavas, which include sodium carbonate (mineral name natrite). While you could argue that although metamorphism is by definition a solid state process and metamorphic calcite is reworked primary carbonate formed from aqueous deposition, it is harder to argue that for the latter.Judge Nutmeg (talk) 23:24, 2 February 2009 (UTC)

ocean acidification[edit]

Also, something should go in here about ocean acidification. People out there have heard of it in relation to current environmental issues and the carbonate in the kidneys example is totally analogous. I'd put something more but I've other chem to be going on with. Menswear 17:35, 5 October 2007 (UTC)

That has absolutely nothing to do with the carbonate ion. LoyalSoldier 05:10, 20 October 2007 (UTC)

Identical oxygen atoms?[edit]

"[The carbonate ion] consists of one central carbon atom surrounded by three identical oxygen atoms in a trigonal planar arrangement" Is there something I'm missing here, or is the use of the word 'identical' here not only superfluous, but also utterly wrong? There's a large number of isotopes of oxygen, and if one of the three atoms in the carbonate ion has a different amount of neutrons from the others, the atoms aren't by any means identical. So shouldn't the word 'identical' be removed from that sentence? --Link (tcm) 17:06, 3 June 2009 (UTC)

I think what is meant is that the oxygen atoms are in equivalent positions. Feel free to reword it.—Tetracube (talk) 17:16, 3 June 2009 (UTC)
Yup, equivalent usually only has meaning depending on the symmetry of the environment. So an isolated, undeformed ion would certainly have three (symmetrically)-equivalent positions. But depending on the environment in a given crystalline phase, this statement may not hold true.Judge Nutmeg (talk) 02:28, 4 June 2009 (UTC)

The isotopes issue is a bit of a red herring, since oxygen-16 is at least 99.7% abundant. I think the discussion of identical (or equivalent) oxygens is important to give weight to the resonance argument - crystallography and probably spectroscopy show that there are three equally long C-O bonds, rather than one short C=O double bond and two long C-O single bonds.

Ben (talk) 02:44, 4 June 2009 (UTC)

Cp. Phosphate ( PO43- ≈ (P+)(O-)4 ). Quantum mechanically, employing the concept of Electronegativity, the central carbon atom surrenders an electron, so coming to electronically (chemically) resemble Boron, having 3 remaining valence electrons. Meanwhile, each of the 3 oxygen atoms "steals" an extra electron, so coming to electronically resemble Fluorine, having 7 remaining valence electrons. Then, the positively-charged carbon forms 3 valence-orbital-sharing covalent single bonds, with the 3 negatively-charged oxygens ( CO32- ≈ (C+)(O-)3 ). If so, then the quantum-scale electron charge distribution, is not what is described, by the "Lewis resonances" picture provided in the article. If the proceeding sentences are accurate, the molecule actually has a positively charged central core (C+), surrounded by negatively charged "arms"( (O-)3 ).66.235.38.214 (talk) 22:43, 4 October 2012 (UTC)