Talk:Carbon dioxide

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This article is a vital article.
Former good article Carbon dioxide was one of the good articles, but it has been removed from the list. There are suggestions below for improving the article to meet the good article criteria. Once these issues have been addressed, the article can be renominated. Editors may also seek a reassessment of the decision if they believe there was a mistake.
edit·history·watch·refresh Stock post message.svg To-do list for Carbon dioxide:

Here are some tasks you can do:
  • Cleanup:
    • More and better references (more print references needed)
    • Use a consistent style of referencing (inline seems the best)
    • Tidy up external links
    • Expand:
    • On other planets (e.g. Venus)
    • More on plants (Mainly their carbon fixation e.g. CAM, C4 plants)
    • More on past levels of CO2 and how they changed (e.g. earth's early atmosphere, the role of cyanobacteria)
    • Write a full lead section when finished (~3 paragraphs)
    • Verify:
    Verify disputed claims and statistics

From ACID nomination:

  • Vital topic for any encyclopaedia, but is in poor shape. Pending a split, and has several lists of things that need doing, if anyone is interested? — Jack · talk · 06:08, Wednesday, 25 April 2007
  • Especially with all of the discussion of it in Global Warming contexts recently. ~ BigrTex 14:58, 3 May 2007 (UTC)
  • Way too long "see also" list, should and could be incorporated into prose. Punkmorten 13:32, 18 May 2007 (UTC)

The Fire Extinguisher Entry is outdated and wrong.

CO2 IS toxic at concentrations higher than 5%. Design Concentrations for Room Flooding systems with CO2 are 40%+ so CO2 is not suitable for occupied spaces. CO2 Flooding Systems are not supported for use in occupiable spaces though many countries such as USA and other third world countries still misuse CO2 in Fire Suppression Systems because it is cheap. The NFPA supports the use of CO2 on electrical hazards though it is not supported globally because CO2 can cause over pressurization, thermal shock, electrical component damage and has human health/toxicity issues. The NFPA organisation is not the definitive word/authority on Fire Suppression it is just one of many organisations involved in making standards for Fire Protection. The NFPA is really relevent only to the USA. USA codes and standards are typically only relevent to the USA so should not be referenced as the main global Fire standard on a site like wiki which serves a global audience (unless wiki is only for Americans). Though CO2 was used many years ago to protect enclosed spaces on Ships, this is extremely outdated. CO2 has caused fatalities on ships in Navies and merchant fleets that it is now superceded in this application by using extinguishants that support human life at design concentrations such as HFC-227 or Novec-1230. Unlike other countries, America and other third world countries still allow the use of CO2 in some applications where humans can be present because CO2 is cheap and installations are not monitored/controlled. (~GRANT)

Density of liquid at 1 atm?[edit]

What's the density of liquid CO2 at 1 atm? 770 kg/m3 (liquid at 56 atm and 20 °C) is not helpful.
~ender 2013-09-29 22:14:PM MST — Preceding unsigned comment added by (talk)

It's not liquid at 1 atm. It goes directly from gas to solid and vice versa. So your question has no answer. --Stephan Schulz (talk) 07:56, 30 September 2013 (UTC)

Misleading statement in opening paragraph[edit]

As Wikipedia articles are supposed to be impartial I would suggest an edit to the following statement, "Burning of carbon-based fuels since the industrial revolution has rapidly increased concentrations of atmospheric carbon dioxide, increasing the rate of global warming and causing anthropogenic climate change." It has not yet been conclusively proven that a rise in man-made CO2 'causes' global warming. This statement has the potential to be both biased and misleading. Rabbit78 (talk) 19:39, 21 October 2013 (UTC) Rabbit78

There are a number of sources presented in this and other articles with regards to carbon dioxide's role in global warming. Can you present a reliable, contrary source. --OuroborosCobra (talk) 20:12, 21 October 2013 (UTC)

ADD: A number of years ago, Wiki write ups on CO2 gas stated clearly that CO2 gas was a "minimal greenhouse gas component" and is a trace component in the earth's atmosphere at 0.035%. CO2 gas was not listed as a greenhouse gas in engineering or environmental literature all through the 60s, 70s, 80s, etc., until the current EPA Admin decreed CO2 as a Greenhouse Gas per se. EPA's decree was politically motivated to be sure. The dominant green house gases in earth's atmosphere are water vapor and methane gas. It is clear from reading Wiki on CO2 gas that it has now become polluted with PC intentions. CO2 levels were hundreds of times higher in earth's history and the oceans did not boil. CO2 gas emissions from the Ocean (which is the leading source of CO2 compared to the miniscule CO2 production by mankind per se Ref: UN Panel report original form with bar charts) are emitted 4-600 years after the Solar Flare activity of the Sun. In short, Solar Flare activity causes major releases of CO2 as opposed to mankind and CO2 is a response to the call of solar activity. This logic becomes more clear when one ponders just why did the ice age Only 14,000 years ago that formed the Great lakes in north America melt due to "global warming"? There was no mankind or industry emitting CO2 as compared to today. My references come from my MS/PhD studies in environmental engineering. [User Nature4U2] [User Nature4U2] — Preceding unsigned comment added by Nature4U2 (talkcontribs) 00:33, 16 December 2013 (UTC)

I also want to know why this is included " Carbon dioxide is an important greenhouse gas, absorbing heat radiation from Earth's surface which otherwise would leave the atmosphere" How is it defined as a greenhouse gas and what is its percentage in the air (I recall somewhere around 0.011 percent) and what is its ability as a "greenhouse" gas compared to water vapor? I may have already stated on one of my websites but I will state here as well: if a beach ball represents the size of this planet, all the humans on it would occupy about the same space as something around the order of hundred to thousands of amoebas - now consider what effect humans really have on this planet. It's so much junk science to be talking about carbon footprints when plants require carbon dioxide to live - perhaps the effort is made to get CO2 down to nothing to cause the human race to be extinct, but of course that couldn't happen because of the enormous natural source of CO2 being produced without any human activity. This article like so many on wiki are heavily slanted towards OBFUSCATION, just like how this site refuses to show the real NEGATIVE 10% GDP growth for the United States upon proper accounting with the actual inflation rate and percentage of the GDP due to the federal deficit to be able to prop up the GDP - wiki is thus into propaganda. Thomas_Blankenhorn (talk) 07:04, 20 January 2014 (UTC)

Not so highly nonmetallic oxide[edit]

Carbon dioxide is often characterised as "well soluble in water", but it is in fact, in standard condictions, rather poorly soluble. 1.45 g/L at 25 °C, 100 kPa - it is weak solubility (1,45 g/kg of water, 0,145g/mL of water). Hydrogen chloride is a good example of a gas which is well soluble in water: 82.3 g/100 mL (0 °C), 72.0 g/100 mL (20 °C), 56.1 g/100 mL (60 °C). Main oxides of the elements with similar level of metallicity (on "carbon diagonal") to carbon are more soluble or much easier react with water: phosphorus trioxide, phosphorus pentoxide, selenium dioxide (38.4 g/100 mL (20 °C), 39.5 g/100 ml (25 °C), 82.5 g/100 mL (65 °C)), selenium trioxide, iodine pentoxide (187 g/100 ml). Even some oxides of typical metalloids are more soluble: boron trioxide (22 g/L), arsenic trioxide (20 g/L (25 °C)). Carbon monoxide has really low solubility in water (27.6 mg/1 L (25 °C)).

Low sublimaton point is not due to especially high nonmetallicity of carbon, because if we compare sublimation point of arsenic trioxide (738 K) to molecular mass of its monomer (about 195, carbon dioxide only 44), we can see that quotient (sublimation point in K/ molecular mass) is higher for carbon dioxide (in comparison with trioxides of sulfur (boiling point ca. 45 C) and selenium (boiling point ca. 165 C) also). In addition, if carbon dioxide was not so volatile (especially if it was similar to silicon dioxide at normal pressures), carbon could not be soo good element to life. (talk) 22:34, 25 October 2013 (UTC)

Semi-protected edit request on 16 February 2014[edit]

Simple change request concerning the line stating: ″Carbon dioxide is a greenhouse gas as it is transparent to visible light but absorbs strongly in the infrared and near-infrared, before slowly re-emitting the infrared at the same wavelength as what was absorbed″. CO2 does not absorb strongly in infrared or near-infrared because of its weak dipole structure (only a few vibration modes can absorb the electromagnetic radiation). Therefore CO2 has a very narrow absorption band. A more important correction is basic physics on how it re-emits infrared radiation. It is thermal radiation from molecular collisions (causing dipole movements of the molecules that produce the radiation). Thus that re-radiation is black-body radiation - all wavelengths centered on the average temperature of the gas. This is an important correction. I forgot to add what the line should become: ″Carbon dioxide, because of its molecular structure, absorbs infrared radiation in only a few narrow bands and is thus a weak greenhouse gas. As for all the gases, that absorbed energy heats the gas and is re-radiated as thermal radiation (broad spectrum radiation caused by the molecular collisions).″ — Preceding unsigned comment added by (talk) 15:06, 16 February 2014 (UTC) Thanks, mark riggle - (talk) 14:45, 16 February 2014 (UTC)

I partly agree. It is true that absorbs strongly is overstated on a per-molecule basis; I would say instead that it absorbs in two vibrational bands (as already stated in the Structure and bonding section). And I think you are write about the thermal radiation. However I oppose referring to a weak greenhouse gas, as this may suggest (to some readers) that it is unimportant. In fact as explained at Greenhouse gas, environmental importance depends not only on molecular characteristics but on abundance, so that CO2 is the second most important greenhouse gas (after H2O) despite having a lower global warming potential than many larger molecules. There is also the fact that the bending vibrational frequency at 667 cm-1 is close to the peak of the Earth's thermal emission spectrum.
So I would instead suggest the following revision -
″Carbon dioxide is a greenhouse gas as it is transparent to incoming visible light from the sun but absorbs outgoing infrared radiation from the ground at its vibrational frequencies (see Structure and bonding above). As for all gases, the absorbed energy heats the gas and is re-radiated as thermal radiation (broad spectrum radiation caused by molecular collisions).″ What do you think of this text? Dirac66 (talk) 00:24, 18 February 2014 (UTC)
I'll risk showing my ignorance here but "As for all gases, the absorbed energy heats the gas and is re-radiated as thermal radiation (broad spectrum radiation caused by molecular collisions)″ sounds wrong to me. The radiation isn't "caused" by molecular collisions - energy is redistributed by same. But more than that: surely (and here I'm open to correction) it doesn't radiate as a block body? Like any other gas, it can only radiate in its lines? William M. Connolley (talk) 09:49, 18 February 2014 (UTC)
Good points, thanks. The term thermal radiation is incorrect for a gas. There are two separate processes: redistribution of energy by collisions which heat the gas, and radiative emission at allowed line frequencies. The thermal redistribution is more relevant for the greenhouse effect which is the subject of this paragraph. With this in mind, the second sentence should be revised too. How about this -
″Carbon dioxide is a greenhouse gas as it is transparent to incoming visible light from the sun but absorbs outgoing infrared radiation from the ground at its vibrational frequencies (see Structure and bonding above). As for all gases, the absorbed energy can be (partly?) redistributed by molecular collisions which heat the gas." Dirac66 (talk) 23:23, 18 February 2014 (UTC)
OK, but I'm still missing the point of "redistributed by molecular collisions which heat the gas". What difference does this make? The energy still "needs" to get (eventually) re-emitted as radiation at some point. The GHG's are sitting in a sea of O2 and N2, and so the thermal redistribution moves the energy into these too, but that's irrelevant as they can't re-radiate it (no?) because they don't have any lines at "thermal" energies William M. Connolley (talk) 12:11, 19 February 2014 (UTC)
The point is that this is the molecular mechanism responsible for GHG atmospheric heating. The energy is not all re-emitted as radiation into space. Some of it is transferred to O2 and N2 as you say, so that makes our atmosphere warmer. At least if the rate of absorption of energy is faster than the rate of radiative emission, which seems to be the case in recent decades. Dirac66 (talk) 18:08, 19 February 2014 (UTC)

Semi-protected edit request on 10 April 2014[edit]

This article mentions methane as being heavier than air. Methane has a relative density of 0.55. (talk) 03:22, 10 April 2014 (UTC)

Corrected, thanks. Materialscientist (talk) 03:49, 10 April 2014 (UTC)