Talk:Carbon

Talk!

Resolved

 – "Case Closed: [first item -- typo]"

"thermodinamicaly" is a typo. Can somebody please fix it? 64.139.4.126 20:34, 30 November 2007 (UTC)

"In German and Dutch, the names for carbon are Kohlenstoff and koolstof respectively, both literally meaning "coal-stuff"."

For the dutch it is a wrong translation. "Stof" rather means (solid) substance than stuff. like a liquid is being called: "Vloeistof", a 'flowing substance'.

Why isn't lampblack/soot/charcoal counted as an allotropic form of carbon? It is a form that is not diamond, graphite or a fullerene. Of course, it isn't crystalline, but that's not a requirement of being an allotrope.

--user:jaknouse

Aren't they just graphite with impurities? -- Tarquin 11:04 Jan 22, 2003 (UTC)

Yes, it's just a mixture of several different allotropes.- (User) WolfKeeper (Talk) 06:00, 2 December 2007 (UTC)

Does anyone know if carbon nanotubes are considered an allotrope or if they are just a subset of buckyballs? Iammaxus 03:34, 23 Dec 2003 (UTC)

All fullerenes. --mav

All allotropes, by definition.- (User) WolfKeeper (Talk) 06:00, 2 December 2007 (UTC)

The Carbon Cycle

Carbon - in the form of differnet kinds of carbon-containing molecules - moves through an endless cycle. These are the stages of the carbon cycle. It begins when plants and algae remove carbon from the environment during photosynthesis. This carbon returns to the atmosphere via several carbon-cycle pathways.

A) Air contains carbon in the form of carbon dioxide gas. Plants and algae use carbon dioxide to make sugars, which are energy-rich, carbon-containing compounds.

B) Organisms break down sugar molecules me by plants and algae to obtain energy for life and growth. Carbon dioxide is released as a waste.

C) Burning fossil fuels and wood releases carbon dioxide into the atmosphere.

D) When organisms die, their carbon-containing molecules become part of the soil. The molecules are broken down by fungi, bacteria, and other decomposers. During this decay process, carbon dioxide is released into the air.

E) Under certain conditions, the remains of some dead organisms may gradually be changed into fossil fuels such as coal, oil, and gas. These carbon compounds are energy rich.

Graphene

Perhaps this should mention graphene (a single layer of carbon atoms) or reference the graphene page 211.30.190.160 10:35, 14 June 2007 (UTC)

Melting and boiling points?

The article currently claims that carbon sublimes instead of melting and also gives melting and boiling points. Clearly some information is missing. --Andrew 03:58, Apr 13, 2005 (UTC)

Missing... right now I'm having too much of it. I'm not an expert, but I've done a search for a phase diagram and adapted one for the article from a source that appears to know what they're talking about—particularly because it mostly contains ranges and estimates, not concrete numbers. Those seem to be a little more tricky:

The CRC handbook 84th ed. gives:

• For graphite a sublimation point of 3825 °C.
• For diamond a melting point of 4440 °C at 12.4 GPa.
• For graphite a triple point at 4489 °C and 10.3 MPa.

And in the elements section:

• For carbon a graphite-liquid-gas triple point of "4492°C at a pressure of 101.325 kPa" ?!, and it sublimes at 3642 °C.

According to Amazon.com's search inside this book, the "4492°C at a pressure of 101.325 kPa" also is in the 85th ed.
According to [1], the CRC 78th ed. apparently gave here:

• For carbon a melting point of ~3550 °C.
• Graphite sublimes at 3825 °C;
• A graphite-liquid-gas triple point at 4492 °C and 10.3 MPa
• A graphite-diamond-liquid triple point at (3830-3930) °C and 12-13 GPa

Lange's handbook, 15th ed. gives:

• For diamond a boiling point of 3930 °C.
• For diamond a melting point of 3500 °C at 63.5 atm.
• And graphite sublimates at (3915–4020) °C.

Huh.

I've put melting point="triple point, ca. 10 MPa<br />and (4300–4700) K" (from the diagram source), and boiling point="subl. about 4000 K" into the article, until somebody finds better data. Femto 12:28, 16 Apr 2005 (UTC)

Thanks! Wow. --Andrew 22:30, Apr 16, 2005 (UTC)

This is a disaster. The melting point and boiling points should be removed from the elements box. This information should be included as a separate paragraph in the entry, or as a separate entry into the mp and bp of carbon. What is in the element box is essentially useless with out the information above. I had edited it and then came to say something here and then decided to let someone else deal with it. Vargob 17:47, 21 February 2007 (UTC)

I agree this is a mess. As it is now, it makes it seem like the melting point is a higher temperature than its boiling point. This makes no sense at all. --Rkelly74 02:16, 23 October 2007 (UTC)

Big lumps of graphite

THe article doent seem to say where the big blocks of graphite (used in nuclear reactors) come from. Are they synthesised, or dug out of the ground?--Light current 10:44, 28 June 2006 (UTC)

They are always synthesized or purified to some degree and recompressed, since natural graphite always has too much boron and other impurities to be a good moderator. This was a key insight of Szilard which made the Chicago first atomic reactor possible. The Germans never did realize it during the war. SBHarris 01:45, 26 April 2007 (UTC)

History of Carbon is wrong.

According to http://www.pnas.org/cgi/reprint/0510489103v1, and http://www-phys.llnl.gov/pdf/1031204.pdf. Don't get me wrong I beleave the charcoal part should be left in.

"Elemental carbon has been known since prehistory,
and diamond is thought to have been first mined in India 2,000 years ago,
although recent archaeological discoveries point at the possible existence
of utensils made of diamond in China as early as 4,000 before Christ."

- Hamster2.0 04:48, 3 May 2007 (UTC)

I agree with this. Carbon does come in the forms of diamond, graphite and charcoal. I don't have any sources to back this up, but this is true. Charcoal is usually counted as not a form, but it is. Just one that is never overlooked. ☺Efansay^T/_C☺ 06:49, 16 June 2007 (UTC)

Boiling and Melting point are wrong

Someone put (?) question marks around it, it´s better to have nothing at all than erroneous facts.. —Preceding unsigned comment added by 89.54.36.239 (talk) 06:57, 9 September 2007 (UTC)

Carbon

The Carbon article has been nominated for the Wikipedia:Article Collaboration and Improvement Drive. Nergaal (talk) 20:25, 20 November 2007 (UTC)

I found melting points

Carbon =(diamond) C 3550 Carbon =(graphite) C 3675 Carbon =(amorphous) C 3675 —Preceding unsigned comment added by 65.92.202.105 (talk) 23:42, 5 December 2007 (UTC)

any reference? Nergaal (talk) 00:36, 6 December 2007 (UTC)

Abundance of carbon mineral

The following statement is provided unreferenced and I could find nothing to confirm it.

Coal is the main source of carbon in mineral form, containing up to 86% of carbon in anthracite.

I'm not sure the statement is correct. I believe there are more abundant carbonates in the Earth's crust, for example, which is the second most abundate mineral group after the silicates—especially calcite and dolomite. (Although anthracite is probably one of the most carbon-rich minerals.) This change was added March 28, 2007 by User:Freecat. — RJH (talk) 20:59, 21 November 2007 (UTC)

While carbonates contain carbon, they are probably not the main [practical] sources of [elemental] carbon. As an analogy, think of the statement "air is the main source of [elemental] oxygen", which is true, despite the fact that most oxygen on earth is bound on minerals or water. --Itub (talk) 13:27, 6 December 2007 (UTC)

The "practical" source of CO2 gas and dry ice is not the air directly, but the fermentation of sugar to make alcohol. One might also reflect on the fact that the lime that goes into portland cement is produced by driving CO2 from limestone back into the atmosphere (from whence it once came) using the combustion of fossil fuels as energy source - resulting in a very high carbon footprint, if practicality is the issue herePlantsurfer (talk) 14:45, 6 December 2007 (UTC)

I thought we were talking about carbon, not carbon dioxide. --Itub (talk) 17:05, 6 December 2007 (UTC)

reference for infobox

I found this great website and I wanted to reference stuff in the infobox. Unfortunatelly I screw up entries.Can someone else do it instead? Thanks! Nergaal (talk) 22:54, 7 December 2007 (UTC)

Abundance of carbon in Earth's crust

I removed the sentence regarding carbon as the sixth most abundant element in the earth's crust because it had a "citation needed" note and upon googling it doesn't even show up in the top 10 most abundant elements (by weight).[2] --Wizard191 (talk) 04:36, 5 January 2008 (UTC)

South Korea production

There's a wrong sentence about natural graphite. In South Korea, most (more than 99%) of graphite is imported. —Preceding unsigned comment added by 150.150.114.124 (talk) 02:25, 18 April 2008 (UTC)

According to this USGS report, North Korea was the 4th largest producer of graphite in the world, after China, India, and Brazil. I'll change the article to reflect this. Cheers Geologyguy (talk) 02:47, 18 April 2008 (UTC)

Semi-protect the page?

this article recieves a large amount of vandalizations from unregistered users. It might be a good idea to semi-protect it.Nergaal (talk) 01:55, 26 January 2008 (UTC)

Diamond decay

I've heard various sources say that diamonds decay into graphite at standard conditions, and others say that they don't. Can anyone find a source that gives the actual rate of decay? Presumably it can be calculated by knowing the activation energy and assuming a probability distribution for heat energy available to individual atoms. -- Beland (talk) 19:09, 11 June 2008 (UTC)

It depends on the value of the activation energy. I don't think it is known accurately, but I've seen some estimates in the range of 70-100 kcal/mol. That is huge. At room temperature, it corresponds to a half-life that is orders of magnitude longer than the age of the universe. At 1000 degrees you might have a reasonable rate. --Itub (talk) 06:01, 12 June 2008 (UTC)

Broken Reference

I removed a broken reference named "hershey" from the article. Possibly the ref was broken due to vandalism but as far as I could tell it was never working in the first place. --Megaboz (talk) 18:25, 9 September 2008 (UTC)

Conflicting abundance numbers

There are several conflicting numbers in the abundance section about hydrocarbons. At first it talks about reserves of 900GT, then, in the next paragraph, it talks about 4000GT of carbon suitable as fuel. And the the little floating box at the side talks about 13.2 x 10^6 GT of Carbon in the form organic compounds in the upper crust. This is totally confusing and needs to be corrected, explained better, or removed. --Dio1982 (talk) 15:16, 23 October 2008 (UTC)

Melting Point/Boiling point

I have been doing some research and found that 3652degC is the melting point of Carbon and that 4827degC is the boiling point. I don't see these figures mentioned anywhere in the article so I'm wondering whether they are accurate or not. The same website stated that graphite had a melting point of 3500degC so this could also be mentioned if it is correct. I have listed my reference here: [3] Bonzostar (talk) 17:56, 6 November 2008 (UTC)

General comment about elemental photos

I'm wondering out loud why many of the photos of samples of major elements in the infoboxes seem to be grainy, badly lit, low resolution images that don't really give much of an idea of what it really looks like close up. Is anyone with access to elemental samples able to take some better photos? (Apologies to user RTC who at least has taken the trouble to upload the current ones). --CharlesC (talk) 23:56, 23 January 2009 (UTC)