Talk:Basic copper carbonate

Thermal decomposition

When copper carbonate is burnt it turns from a green colour to a black colour then it slowly spreads out.

the above description is also can be apply in most of the copper compound, so i think no need to add that to the page.CuCO3--burning-->CuO Superdvd 23:45, 15 January 2007 (UTC)

It's not technically burning, it's thermal decomposition to Copper(II) oxide--Rossheth | Talk 19:18, 5 June 2007 (UTC)

At what temerature does copper carbonate decompose into copper oxide and carbon dioxide? I've found different answers all over the place. I am a lemon 02:54, 12 June 2007 (UTC)

After a bit more searching on a slow connection it seems that most websites say it's 200*C, although I've found everything from 175 to 300. 200*C, according to this article, is copper carbonate's melting point. Can anyone confirm this? I am a lemon 03:01, 12 June 2007 (UTC)

I think the equation for the formation of Cu(OH)₂.CuCO₃ is missing an oxygen molecule in the reactants side. Leafy Sea Dragon 00:28, 28 June 2007 (UTC)

Copper bicarbonate

I think that copper bicarbonate, a similar compound, should be included too, just as basic copper carbonate is. Copper bicarbonate is a blue solid that decomposes upon heating at the same temperature as copper carbonate. It can be made by reaction of a soluble copper salt and sodium bicarbonate. —Preceding unsigned comment added by 98.221.179.18 (talk) 01:58, 14 February 2010 (UTC)

Is this correct? Some sources say that attempts to prepare the bicarbonate in solution still yield the basic carbonate. --Jorge Stolfi (talk) 15:35, 29 August 2016 (UTC)

CAS number

The CAS number is incorrect: Basic Copper Carbonate: CAS Registry Number: 12069-69-1. — Preceding unsigned comment added by 121.217.69.146 (talk) 08:38, 2 May 2013 (UTC)

Solubility

Hello,

The "properties" section of this article indicates copper carbonate is "soluble in acetic acid".

This seems rather unlikely : CO₃^2- ions should immediately react with acetic acid giving off CO₂ and water, rather than simply stay in solution.

Therefore, it would seem to me that, in acetic acid, copper carbonate decomposes to copper acetate, rather than simply solubilize as is.

The fact that aqueous solutions of acetic acid (white vinegar) are often used to etch verdigris is probably what lead to this statement.

So, I think it should be promptly removed, unless someone provides a trustworthy source stating that copper carbonate is soluble in pure acetic acid without decomposition of the carbonate ions.

Thank you.

Solubility product:

since May 6, 2014 a solubility product of 7.08 x 10⁹ is stated (unfortunately without mentioning a source).

Solubility products of insoluble or very poorly soluble salts are lower than 10^-5. So probably 7.08 x 10⁹ should read 7.08 x10^-9 instead.

However, is there any indication if this value would be correct?

Regards, hermann_oh

193.158.103.164 (talk) 17:03, 22 February 2017 (UTC)

Neutral copper carbonate CuCO₃

Dear all, Searching in the scientific literature, it appears that CuCO₃ does not exists as such: it was never found in nature, neither synthesized in laboratory. You can check it in this article, p.8 (and references therein). Therefore, the text of the page should be heavily edited. I am starting now, not sure that I will have time to finish. — Preceding unsigned comment added by LatinScience (talk • contribs) 07:21, 11 April 2011 (UTC)

After a brief search I get an idea that all "copper carbonate" is actually "basic copper carbonate", and that thermal decomposition of the latter does not necessarily produce the former (as some sources and this article claim) but likely proceeds further up to CuO. Materialscientist (talk) 08:02, 11 April 2011 (UTC)

The crystal structure of CuCO₃ has been reported: Z. anorg. allg. Chem. (1974) 410, 138–148. I can't access the paper right now (some sort of error with the publisher's systems, apparently) but I've got the structure. It is not unheard of for crystal structures to have been determined for compounds that don't actually exist, so I'm not saying this is incontrovertible proof that copper(II) carbonate exists. However, a 1998 Journal of Chemical Education paper about copper carbonates (J. Chem. Educ. (1998) 75, 453–456) was corrected to state that CuCO₃ does exist and has been characterised: Gamsjäger & Preis, J. Chem. Educ. (1999) 76, 1339. --Ben (talk) 09:37, 11 April 2011 (UTC)

Ben, thanks - the Z. anorg. allg. Chem. (1974) 410, 138–148 article does report XRD and some thermal data and the crystal structure solution. Other articles simply echo it. Materialscientist (talk) 01:43, 12 April 2011 (UTC)

My mistake - since yesterday, I found the Gamsjäger reference. Thus, CuCO₃ does not exist in nature but, as stated by Gamsjäger: "Although apparently CuCO3 has not yet been found in nature, it has certainly been synthesized (3, 4). Moreover, both its solubility and its standard Gibbs energy of formation have been determined (5)." and "The transformations of [...] azurite into copper carbonate occur at 25 °C and CO2 partial pressures around [...] 4.57 atm [...]." (3) Ehrhardt, Johannes & Seidel, Naturforsch. B 28b, 682 (1973). (4) Seidel, Viswanathan, Johannes & Ehrhardt, H. Z. anorg. allg. Chem. 410, 138–148 (1974). I will try to find these old articles today to check the content properly. I keep you posted. — Preceding unsigned comment added by LatinScience (talk • contribs) 01:23, 12 April 2011 (UTC)

What is the article about? Is it the basic carbonate or the non basic and difficult to prepare CuCO₃? My view is that the article should be renamed basic copper carbonate as that is the normally encountered form, and most of the article is about the basic carbonate anyway. Axiosaurus (talk) 10:28, 24 July 2014 (UTC)

Added reference to production of the unstable CuCO₃ form. The nice structure image is based on a 1961 paper which was based on powder samples and proposed a rhombohedral crystal. The 1974 Siedel et al paper CuCO₃ paper describes a monoclinic crystal with 5 coordinate Cu rather than octahedral.Axiosaurus (talk) 09:48, 1 August 2014 (UTC)

Got rid of some of the confusion between CuCO₃ and the commonly available basic salt. Still more to do. Axiosaurus (talk) 15:42, 22 October 2014 (UTC)

I have correcte the article to reflect the fact that the actual compound is a basic carbonate. there is very little on the "real" CuCO₃. This compound is misreported in lots of chemical databases- pubchem chemspider etc. Also some elemntary text books quote the decomposition of CuCO₃. Axiosaurus (talk) 10:19, 12 December 2014 (UTC)

I would prefer the opening definition to begin with the same term as the article title. At the moment, the article title is "Basic copper carbonate", yet the article begins "Copper(II) carbonate CuCO3 is not known to occur naturally". OK, maybe the article gets there eventually, but at this point one is for the moment confused about the article's main subject matter and the connection between these two things. 86.136.150.146 (talk) 15:01, 15 December 2014 (UTC)

changes made. I was waiting to see if the page was moved to the new name before changing the lede. Axiosaurus (talk) 16:01, 15 December 2014 (UTC)

Thompsonswiki has just moved the page to new name copper (ii) carbonate which is correct and he also corrected the cas no, so why some one undo it, and the chemical reaction was also correct, and now the chemical formula is also wrong. — Preceding unsigned comment added by 5.101.105.130 (talk) 10:33, 6 January 2015 (UTC)

The original article prior to December 2014, was called CuCO₃, but all of the information contained in it actually referred to the basic mixed salt which is why the article name was changed to refer to the basic copper carbonate. (The name basic copper carbonate-- the word basic indicates that the salt, (e.g malachite form) contains hydroxide, both carbonate and hydroxide anions are present in the ionic lattice of malachite. True CuCO₃ cannot be precipitated from aqueous solution. Simple attempts at e.g. double decomposition reaction fail, what precipitates is a mixed salt usually the malachite form. CuCO₃ as a solid has been made, there is one paper and it is mentioned in the article where a succesful prep was achieved and the compound examined crystallographically, however this was a reaction of CaO and CO₂ at high T and under high pressure CO₂. Why CuCO₃ is unstable and why it cannot be precipitated from aqueous has not been determined.Axiosaurus (talk) 14:36, 6 January 2015 (UTC)

I created an article for the true copper(II) carbonate (called "neutral copper carbonate" in some articles) with the details on synthesis, crystal structure, etc. Hopefully that will reduce the reader's confusion. --Jorge Stolfi (talk) 15:29, 29 August 2016 (UTC)

Removed chem textbook recipe

The following text is removed from the article:

The formation of basic copper carbonate can be verified in the following steps:
a) Centrifuge (or filter) the above-mentioned solution; 1 minute at 6000 g is sufficient
b) Wash the precipitate with distilled water and centrifuge or filter again
c) The colour of the precipitate is blue, like that of several copper salts but none of the sodium salts
d) If dilute (1M) hydrochloric acid is added, then bubbles of CO₂ will emerge and the precipitate will be fully solubilised. These would not be formed if dilute hydrochloric acid was added to solid Na₂SO₄.

This type of instruction is more appropriate for a wikibook in elementary chemistry, not for an encyclopedia. --Jorge Stolfi (talk) 15:28, 29 August 2016 (UTC)

Removed dubious text

I removed the following items that were commented out in the article, and claimed to be incorrect:

Copper in moist air slowly acquires a dull green coating because its top layer has oxidised with the air. Some architects use this material on rooftops for this interesting colour. The green material is a 1:1 mole mixture of Cu(OH)₂ and CuCO₃:

Masterson, W. L., & Hurley, C. N. (2004). Chemistry: Principles and Reactions, 5th Ed. Thomson Learning, Inc. (p 498).

2 Cu_(s) + H₂O_(g) + CO₂ + O₂ → Cu(OH)₂ + CuCO_3(s)

Copper(II) carbonate crystal structure

The comments claim that the structure is "dubious - the sample was almost certainly not copper carbonate but some mixture- struture determination based on powder photograph not single Xtal- structure of CuCO3 in later paper, 1974 Siedel, is different". Anyway, it refers to the neutral copper(II) carbonate and not the basic carbonate. --Jorge Stolfi (talk) 03:36, 30 August 2016 (UTC)

Preparation in solution from carbonate: not so simple

The chemistry of the CuSO4 + Na2CO3 reaction does not seem to be as simple as stated in the text. This 1927 paper seems to claim that the composition of the result varies depending on the proportion of reagents, and that in some cases the precipitate also contains basic copper sulfate Cu2SO4(OH)2 (?) in addition to basic carbonates. --Jorge Stolfi (talk) 04:14, 30 August 2016 (UTC)

Preparation in solution from bicarbonate

There seems to be no bibliography on copper(II) bicarbonate (except one mention in a copper corrosion book). Presumably it does not exist at ambient conditions. However, the reaction CuSO4 + NaHCO3 may give azurite instead of malachite. --Jorge Stolfi (talk) 04:14, 30 August 2016 (UTC)

Phase diagram of basic carbonates

The Reitner 1981 reference has a phase diagram for the solid phase of copper(II) salts in presence pf water and carbon dioxide at various partial pressures. That diagram should be reproduced in the article. It may explain why azurite may be formed instead of malachite. --Jorge Stolfi (talk) 04:14, 30 August 2016 (UTC)