Talk:Acetylene

message: What is the black substance that comes off from the flame and floats away into the air when starting up an oxy-acetelyne torch?
:Lampblack. Of course, it wouldn't be surprising to find it contains buckyballs as well.
:Atlant 22:02, 30 March 2006 (UTC)
thread_title:  What's that stuff? 

message: Please correct the following:
a liquid does not sublime, by definition.
A material can not sublime at its boiling point, again by definition (although there may be exceptions...)
The boiling point can not be BELOW the melting point (under the 
same pressure and temperature).  
:I changed the melting point to the latest (1931) value reported in the webbook 171.65 K (link: http://webbook.nist.gov/cgi/cbook.cgi?ID=C74862&Units=SI&Mask=4#Thermo-Phase). Marenero (talk) 20:49, 16 July 2012 (UTC)
replies: text: I believe this change is based on an error. Rather than add a long explanation in the middle of this old discussion, I have added a new section below. See Talk:Acetylene#Melting point, boiling point, triple point, sublimation Dirac66 (talk) 01:42, 17 July 2012 (UTC)

text: From my distant memory Acetylene will decompose at around 15psi spontaneously, releasing lots of energy (in an explosion).  It is stored in Acetone in welding cylinders to prevent this (as it dissolves readily and thus has a lower partial pressure).  There are hotter flames using different oxidisers or reducers, but acetylene + oxygen is the hottest hydrocarbon - oxygen flame AFAIK. --njh 11:41, 25 May 2006 (UTC)
thread_title:  wha?

message: Why does the article claim that the chemical name of the compound is acetylene when it should be ethyne? In alkyne it states that the acetylene is officially known as ethyne which I assume is refering to IUPAC nomenclature.
* I think that we should use IUPAC names everywhere and then have redirects from common names, rather than the alternative. But it'll never happen.Jaredjeya (talk) 20:56, 7 November 2014 (UTC)
replies: text: I think we should follow the usage of most recent textbooks and scientific articles. IUPAC is not the only authority. Dirac66 (talk) 14:13, 9 November 2014 (UTC)
thread_title:  Acetylene or ethyne 

message: Why is the compound even called acetylene at all? I see no similarities to the acetyl radical. No methyls, no carbonyls (not even an oxygen atom), nothing.
:The OED gives the etymology as [f. ACETYL + Gr. -ηνη female descendant, weaker derivative: see -ENE.
:The Oxford Dictionary of English gives the origin as: mid 19th cen.: from acetic acid + -yl + -ene.
:See also EtymOnline, :Wiktionary:Acetylene, reactions of alkynes.
:Acetylene can be hydrated to acetaldehyde, which contains the acetyl group and may account for the name. Acetyl compounds could, in principle at least, be dehydrated (often a facile reaction, no change in oxidation state) to C2H4 - an unsaturated hydrocarbon (hence -ene) from an acetyl group, hence acetylene.
:
:Ben (talk) 19:04, 2 February 2009 (UTC)
thread_title:  Why "acetylene"? 

message: History and tradition, most likely some misconception by the person(s) who first discovered or synthesized it.
Look up how hydrocarbon came about from early experimenters calling them 'watered carbons' due to all the hydrogen in them which had to be an indicator of water involved in the processes that create them. Of course the assumptions were wrong but hydrocarbon stuck as the name of that class of compounds.
:You might be thinking of carbohydrates? --njh 11:43, 25 May 2006 (UTC)
thread_title:  Why? 

message: "Oxyacetylene is the hottest burning of all fuel gases."  What counts as a fuel gas?  There are hotter stuffs: .  A whole bunch of poluynes go noncharted in thèrmokemistry. -lysdexia 20:40, 30 September 2006 (UTC)
thread_title:  bad wording? Acetylene is not so hot. 

message: In the "Uses" section:
"Acetylene has been proposed as a carbon feedstock for molecular manufacturing using nanotechnology. Since it does not occur naturally, using acetylene could limit out-of-control self-replication."
In the "Natural occurrence" section:
"Acetylene is a moderately common chemical in the universe... Natural acetylene..."
How could the two quotes square with each other?  Given the second one, the first is conceptually flawed. Shawn D. 16:37, 25 July 2007 (UTC)
thread_title:  Flawed Nanotechnology Concept? 

message: We've been studying reactions in chemistry lately, and yesterday we demonstrated the synthesis and combustion of acetylene.  Did I hear my teacher wrong when he said that some acetylene torches can burn underwater?  —Preceding unsigned comment added by 71.190.143.208 (talk) 19:32, 25 October 2007 (UTC)
replies: text: Acetylene torches have their own oxygen tank. Maybe that's enough to make them burn underwater? --Itub 14:53, 26 October 2007 (UTC)
replies: text: The combination of the bottled acetylene combined with the bottled oxygen could theoretically allow it.  However, on the torch tips I know of, the acetylene and oxygen streams combine externally after exiting individual holes -- the water could entrain the gases and prevent them from mixing and igniting or maintaining ignition. Shawn D. 15:46, 29 October 2007 (UTC)
replies: text: I just looked at the article on oxy-fuel welding and cutting. From what it says, it seems to me that oxy-acetylene torches could work underwater, but only at very low pressures, so hydrogen is used instead. --Itub 08:50, 30 October 2007 (UTC)
thread_title:  Underwater? 

message: The Compression section says "acetylene gas is fundamentally unstable, and will decompose in an exothermic reaction if compressed to any great extent." I can't find anywhere in the article, though, what it becomes when it decomposes. What are the decomposition products? Ian01 (talk) 04:14, 7 October 2008 (UTC)
replies: text: Not sure, but I suspect carbon and hydrogen. I think what's meant by "fundamentally unstable" is that acetylene has a positive heat of formation; that is, the reaction H2 + 2C -> C2H2 is endothermic. --Itub (talk) 07:01, 7 October 2008 (UTC)
thread_title:  Decomposition 

message: I heard a rumor that you have to store and transport acetylene tanks standing up and that if you lay them on their sides they will explode?
I don't use acetylene, but I do use a GTAW welding rig with pressurized argon. My argon tank lays on its side in a cradle under my welding bench.
I think it's safer to have gas tanks lay on their sides and not standing up as they could not tip over if they are already laying on their sides.
I don't want to change the article because I only heard this as a rumor. Is there any cited source that talks about en explosion that is caused by someone laying an acetylene tank on it's side?
Allyn (talk) 13:44, 25 July 2009 (UTC)
replies: text: This website United States Department of Labor: Special Hazards of Acetylene includes the words ACETYLENE CYLINDERS SHOULD BE STORED AND USED IN THE UPRIGHT POSITION AND FIRMLY SECURED TO PREVENT FALLING OR BEING KNOCKED OVER. (their capitals) Dirac66 (talk) 12:28, 10 August 2014 (UTC)

text: I have now added a link to the above noted US Dept of Labor (Mine Safety and Health Administration) site, which explicitly specifies the upright position. Dirac66 (talk) 16:02, 20 March 2016 (UTC)
thread_title:  Is it true that acetylene tanks have to be stored and transported standing up and not lay on their sides? 

message: Here's a link to an article that would seem to contradict the information in the Natural occurrence section.
http://www.newscientist.com/article/dn19005-hints-of-life-found-on-saturn-moon.html  —Preceding unsigned comment added by SargeWallace (talk • contribs) 13:36, 6 June 2010 (UTC)
thread_title:  Natural occurrence 

message: From section wha? above:
1. Beginning of old comment (added 2005 Oct.1 by numbered editor)
Please correct the following:
a liquid does not sublime, by definition.
A material can not sublime at its boiling point, again by definition (although there may be exceptions...)
The boiling point can not be BELOW the melting point (under the 
same pressure and temperature). Etc. 
2. Added today by Marenero:
:I changed the melting point to the latest (1931) value reported in the webbook 171.65 K (link: http://webbook.nist.gov/cgi/cbook.cgi?ID=C74862&Units=SI&Mask=4#Thermo-Phase). Marenero (talk) 20:49, 16 July 2012 (UTC)
thread_title:  Melting point, boiling point, triple point, sublimation 

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thread_title:  External links modified 

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thread_title: Assessment comment

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thread_title:  External links modified 

message: I'm currently doing an apprenticeship for fabrication and in another fabrication book it notes that Acetylene has a strong garlic smell. would this be the "marked" odour that's mentioned at the beginning of this article? Wiki states that it is odourless in its pure form but has a marked odour commercially due to impurities.  — Preceding unsigned comment added by 82.39.201.117 (talk) 08:49, 9 February 2021 (UTC)
thread_title:  Identifying Acetylene 

message: Hello, may you have different references or parameters, but your density is wrong. In the English version it is written 1,097 kg/m^3 (without information about the other parameters) but in the German one (with reference) with 1,1772 kg/m^3 (at standard conditions).
Please correct or specify it.   [Added 29 April 2021 by editor 2003:f9:872d:f806:a5dd:6a6c:2915:874]
:The Infobox of this English article has a link at the bottom saying Infobox references, but it does not seem to lead to any useful statement of where the value 1,097 kg/m^3 comes from. In effect it is unsourced. On the other hand the value in the German article does have an intelligible source (even with my very limited German!), so I am tempted to just insert the value from the German article here, with the German reference. Does anyone have a better idea? Dirac66 (talk) 00:21, 19 May 2021 (UTC)
replies: text: Done. I have now added the value and source from the German article. Dirac66 (talk) 18:11, 16 June 2021 (UTC)
thread_title:  Density 

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thread_title:  Copyright problem removed 

message: The Discovery section now says: "By heating potassium carbide with carbon ... [Davy] produced a residue of what is now known as potassium carbide." How can potassium carbide react to form potassium carbide?? 
This was changed on 2022 January 2 from "By heating potassium carbonate with carbon ..." which at least had a reactant different from the product. However the reaction with carbonate was not very clear either - what happens to the oxygens?? And I cannot make much sense of the references given. Can someone make sense of this reaction and then correct the sentence? Dirac66 (talk) 03:32, 22 January 2022 (UTC)
thread_title:  Discovery: carbide reacts to form carbide?? 

message: From the "Discovery" section: "By heating potassium carbide with carbon at very high temperatures, he produced a residue of what is now known as potassium carbide, (K2C2), which reacted with water to release the new gas."
So he heated potassium carbide and got potassium carbide out of it? What is this sentence supposed to mean?
2A02:8108:96C0:6D08:1816:CC57:5704:15FB (talk) 17:52, 7 February 2022 (UTC)
replies: text: It actually says "By heating potassium carbonate with carbon at very high temperatures, he produced a residue of what is now known as potassium carbide, ... Dirac66 (talk) 01:12, 12 May 2023 (UTC)
thread_title:  Confusing sentence 

message: Perhaps I'm being dull but I'm not sure what "reduced carbon" is. The article says "oil supplanted coal as the chief source of reduced carbon". 
Does it simply mean pure carbon (graphite), or does it mean carbon with a formal charge/oxidation state less than it normally is? In typical molecules such as hydrocarbons, carbon's formal charge tends to be 0. And it doesn't tend to be reduced further in reactions.
I feel that it's possible the editor related isolating pure carbon to isolating pure metals, which do tend to have a reduced oxidation state after the purifying process. But this would be an incorrect analogy.
But I may be missing something here and I haven't found out how to read or translate the cited source, so any insight's appreciated. 35drake (talk) 13:55, 1 February 2023 (UTC)
replies: text: It means carbon with a lower oxidation state than the maximum of +4 in CO2. Dirac66 (talk) 01:07, 12 May 2023 (UTC)
thread_title:  What is reduced carbon?