Talk:Carbon dioxide

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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 awaiting attention:
  • 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The Fire Extinguisher Entry is outdated and wrong.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)

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Methane - mentioning greenhouse gas potential[edit]

@Carlos Danger: I see no useful purpose of mentioning methane as you have done here and here. Its mention belongs in other articles such as Greenhouse gas. Not here. Jim1138 (talk) 08:18, 21 December 2016 (UTC)

Is CO2 odorless?[edit]

There is currently an edit war following a video by Thunderf00t https://www.youtube.com/watch?v=qF7qJ1K4VOk The video claims that CO2 has a sharp, acidic odor. This is due to the formation of acid when CO2 reacts with water, so we might argue that it is not CO2 itself that we smell. Safety data sheets list CO2 as odorless or having "no odor warning properties" so I think we should keep the "odorless" label and maybe explain the reason of the acidic smell somewhere else.

--2A01:CB1C:8DC:7300:85C7:A731:B090:DFF (talk) 21:39, 26 April 2017 (UTC)

If it generates a smell when it reacts with your nose, by definition it must have an odour, right? I think 'odour' refers to the sensation, not the chemical process that leads to it. Illiteration (talk) 22:06, 26 April 2017 (UTC)

It really should be specified. Whether or not it has an odor is entirely dependent on the concentration. Pure CO2 has a sharp smell but levels that will asphyxiate someone don't. — Preceding unsigned comment added by 96.253.22.191 (talk) 22:37, 26 April 2017 (UTC)

I just noticed, the article already mentioned this: "At low concentrations, the gas is odorless. At higher concentrations it has a sharp, acidic odor." Is it normal in the field of chemistry to refer to a chemical as odourless if it has no smell at normal concentrations? Illiteration (talk) 23:34, 26 April 2017 (UTC)
It depends. At low enough concentrations, hydrogen sulfide is odorless. At 100%, it might have a smell but no one is alive to report it. Carbôn dioxide may or may not be odorless at normal concentrations, but from our point of view it is odorless - we are used to it. If you stick your head into a dry ice chest, it has an odor.JSR (talk) 00:41, 27 April 2017 (UTC)
At this point the odor question is still hypothetical. The video doesn't really use a conclusive test. There's semantics involved as to what actually constitutes an odor as well as gas concentration being relevant. Until these issues can be resolved by high sigma testing and linguistic/practical verification as to if an odor is specifically an olfactory sense or a more general term I feel it is premature to edit the article and it should be left as "odorless".79.68.125.23 (talk) 01:29, 27 April 2017 (UTC)

Comment Wikipedia goes by what wp:reliable sources state. One MSDS http://www.uigi.com/MSDS_gaseous_CO2.html - Carbon Dioxide gas is colorless. At low concentrations, the gas is odorless. At higher concentrations it has a sharp, acidic odor. It will act as an asphyxiant and an irritant. Please use RS. Our opinions here are irrelevant. Jim1138 (talk) 05:03, 27 April 2017 (UTC)

Right now the article uses two asterisks to point the reader to another section of the article within the first sentence. I don't think that's a good flow for the article; I think the details of the smell should be mentioned in the lead section of the article. To do this, we should probably remove any mention of the odour/lack thereof from the first few sentences and put it later on in the lead section, so we can spend more than a few words explaining it.

And to get the facts straight, from what I've gathered, CO2 has no smell in regular, low concentrations. In order for there to be enough for you to smell, it would already have to be past the point where you'd asphyxiate (from lack of oxygen?), unless you take it in short bursts like Thunderf00t did. Does anyone disagree with that? Illiteration (talk) 15:50, 27 April 2017 (UTC)

There is no more edit war, at least not from IPs. DMacks, I went a step further and semi-protected it; I hope you don't mind. Drmies (talk) 18:16, 27 April 2017 (UTC)

Good idea. DMacks (talk) 19:25, 28 April 2017 (UTC)

Well, the article says it's both odorless and acidic with no explanation as to why the confusion, so maybe you mods should stop blindly reverting changes and lock it into a state that has some sense of credibility.— Preceding unsigned comment added by 174.233.137.8 (talk • contribs) 18:39 27 April 2017 (UTC)

Reliable source needed Does anyone have access to a wp:reliable source on the odor threshold of CO2? It appears that if you detect the "sharp, acidic" odor/sensation, you will quickly asphyxiate. But, you would not get this sensation/odor at lower, but still hazardous-to-lethal levels. A good reference should probably be added to the three mentions of odor. Possible sources for which I do not have sufficient access to:

Many MSDSs just state "odorless", some state 'high level sharp/acidic'. With a citation, perhaps the infobox should be changed to "No odor<br>High concentrations:<br>sharp; acidic".

What should be mentioned about of "odor" and its importance in the article? Probably not what you would smell if you inhaled a 100% gas or snort the material. A chemist, for instance may want to know if a chemical would have an odor below a dangerous level. Example: per Phosgene#Safety does have an odor, but its detection level is about four times its hazard level. This MSDS states Odour: Initially, musty hay, then the sense of smell is deadened. Hydrogen sulfide at high/lethal levels quickly deadens the sense of smell. Odor threshold detection can be complicated. Jim1138 (talk) 21:24, 27 April 2017 (UTC)

I think the problem (other than finding sources) is that it's hard to summarise the points of its odour in just a few words. Right now the infobox says "Low concentrations: Odorless", "High concentrations: Sharp, acidic", which is redundant because everything is odourless in low enough concentrations. I stick by my earlier suggestion of making no mention in the first few sentences to keep the beginning clean, and then go into detail on the odour later on in the lead section. Illiteration (talk) 21:42, 30 April 2017 (UTC)
@Illiteration: That's what the RS states. We need non-wp:original research. Jim1138 (talk) 23:40, 30 April 2017 (UTC)
  • Ryanharmany added odor info from an MSDS and a citation. American English per top of page. I copied the odor info and reused ref to Chembox. Jim1138 (talk) 23:43, 28 April 2017 (UTC)

"No smell in low [enough] concentration" is true of every single substance in the world, it's almost tautological. I'm not sure I see the logic in bothering to write that. Even for safety reasons, knowing that isn't going to help you much until you get some symptom that IS noticeable, namely feeling yourself suffocate in this case, at which point it is a bit redundant whether there's a smell isn't it? — Preceding unsigned comment added by 64.180.192.224 (talk) 23:23, 12 May 2017 (UTC)

Semi-protected edit request on 27 April 2017[edit]

Wikiplschecksources (talk) 23:07, 27 April 2017 (UTC)

Not done: it's not clear what changes you want to be made. Please mention the specific changes in a "change X to Y" format. Murph9000 (talk) 23:12, 27 April 2017 (UTC)

Atmospheric carbon dioxide is vital to life on Earth[edit]

The statement "Atmospheric carbon dioxide is vital to life on Earth" is incorrect. Humans get their carbon from food and plants get some of their carbon from the soil, not from atmospheric CO2. Brian Everlasting (talk) 18:59, 29 April 2017 (UTC)

The point is that carbon dioxide is the primary source of carbon for life on earth. Whether heterotrophic organisms eat it or not is irrelevant. Their source of carbon in the food they eat is carbon dioxide fixed by autotrophic organisms. Plantsurfer 19:09, 29 April 2017 (UTC)

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