Talk:Stoichiometry

message: All these articles (Stoichiometry,Stoichiometric coefficient,Gas stoichiometry)are related to the same concept and would be better if they are accessible on a single page. It will help by providing a better understanding of the article and save some trouble for a person new to the concept. Myth  (Talk) 21:00, 28 January 2007 (UTC)
replies: text: They should be merged until it is true that they have grown and developed enough information to merit their own space in separate articles. --Antonio.sierra 01:32, 6 September 2007 (UTC)
thread_title:  Merger proposal 

message: I might just suck at counting, but I believe in "Different stoichiometries in competing reactions" there is an extra Hydrogen. Well actually it's an extra n hydrogens, but I think people get it... WAIT!!! that does say 6-n... hm... LIMEY 07:09, 2 December 2007 (UTC)
thread_title:  Counting 

message: This article needs to mention something about Job's method.  —Preceding unsigned comment added by 204.8.12.66 (talk) 15:16, 9 January 2008 (UTC)
thread_title:  Addition 

message: The article says,
"the units of grams form a multiplicative identity, which is equivalent to one (g/g=1), with the resulting amount of moles (the unit that was needed), is shown in the following equation,
:\left(\frac{2.00 \mbox{ g NaCl}}{1}\right)\left(\frac{1 \mbox{ mol NaCl}}{58.44 \mbox{ g NaCl}}\right) = 0.034\ mol"
however it leaves out the NaCl at the end. Shouldn't it be still there as there are two "NaCl" in the numerator while there is one "NaCl"in the denominator,
:\left(\frac{2.00 \mbox{ g NaCl}}{1}\right)\left(\frac{1 \mbox{ mol NaCl}}{58.44 \mbox{ g NaCl}}\right) = 0.034\ mol \mbox{ NaCl}
(Unless, of course, that italicized "mol" means you don't have to, i dunno...)Electric durian (talk) 07:10, 20 September 2008 (UTC)
thread_title:  Is this correct? 

message: Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry
Well now then shouldn't "composition stoichiometry" have a page or at least some definition.  —Preceding unsigned comment added by 134.131.125.50 (talk) 21:36, 22 October 2008 (UTC)
replies: text: Logan Talk Contributions 23:13, 3 February 2010 (UTC)
thread_title:  Where is composition stoichiometry? 

message: The article is too centered on the theoretical calculations, which makes it difficult to understand to someone not previously knowing the subject. It should also explain how the experiments are performed and how the "amount of products that can be produced" is measured in practice (not just as the result of a previously defined formula). That is, explain the basis of the technique instead of only the way it's used. Diego (talk) 15:26, 5 January 2010 (UTC)
thread_title:  Explain the practical side 

message: I've rewritten the intro to make it less technical and hopefully less daunting for the non-technical reader.  Almost all the original text from the previous version has been kept, but I've rearranged it to bring the example forward and improve the flow of ideas.  Also, I've explicitly defined both reaction and composition stoichiometry, as the wiki link in the previous version to composition stoichiometry didn't work (a page on composition stoichiometry may never have existed).  
Chemists, help me out here!  I'm hoping with a bit more work, we can get rid of the "too technical" tag that has been placed on the article. Pls review the examples and definitions for accuracy.  Also needed are some definitional references to good chemistry textbooks for the various terms defined (I don't have access to any chem textbooks at the moment, and most of the web-based definitions aren't from clearly authoritative sources).  
Ross Fraser (talk) 00:29, 19 July 2010 (UTC)
thread_title: Non-technical intro

message: In the section defining the stoichiometric coefficient, there are sign errors. 
"CH4 + 2 O2 → CO2 + 2 H2O, the stoichiometric coefficient of CH4 would be 1 and the stoichiometric coefficient of O2 would be 2."
According to the definition of the "stoichiometric number" by IUPAC, the sign (consumption or production) is included in the coefficient. So in the example the stoichiometric coefficient of CH4 would be -1 and the stoichiometric coefficient of O2 would be -2.
http://www.iupac.org/goldbook/S06025.pdf
Nicolas Le Novere (talk) 16:19, 17 September 2010 (UTC)
replies: text: I agree that this needs revision, but see below. KeeYou Flib (talk) 13:33, 19 April 2021 (UTC)
thread_title:  Error of sign 

message: The paragraph starting with "The (dimensionless) "units" may be taken to be molecules or moles. " does not make sense. Stoichiometric numbers are dimensionless because in the current interpretation of reaction kinetics, they represent the substance consumed/produced relative to an hypothetical substance which stoichiometric number would be 1. Another way of saying that is they represent the number of moles/molecules transformed per number of moles/molecules of reaction events. Because it is mole/mole or molecule/molecule, the result is dimensionless. It may not be taken as to be anything. dimensionless is dimensionless. We are talking of the dimensions of the SI units here. mole/mole = second/second = meter/meter = kg/kg.
Nicolas Le Novere (talk) 16:19, 17 September 2010 (UTC)
thread_title:  dimensionless 

message: In earlier versions there was a section called Definition, that elaborated on the basic concepts. Was it deliberately removed or did it get lost in the wiki cut-n-paste process? I'm restating it into the article, since it seems to have been lost to vandalism. Diego Moya (talk) 13:23, 30 October 2010 (UTC)
thread_title:  What happened to the 'Definition' section? 

message: There is an error in the mass ratio of air/natural gas for stoichiometric combustion.  The ratio is listed as 14.5.  Since NG is mostly methane, the ratio should be closer to 17.2 (the correct methane/air mass ratio).  Since the table does not give the exact composition of (for example) NG or gasoline, and both of these substances have variable composition, it would be better to cite the NG and gasoline composition for which these ratios are stated.  71.136.237.55 (talk) 20:31, 4 July 2011 (UTC)
replies: text: You have a valid point. Gasoline is a complex mixture, but C8H18 is certainly a more representative formula than C so I have now changed it. And for the same reason, I have changed Diesel from C to C12H26. Dirac66 (talk) 23:24, 10 July 2018 (UTC)
thread_title:  Error in Stoichiometric Air Fuel Ratios 

message: "1 mol of ammonia consists of 1 mol of nitrogen and 3 mol of hydrogen. As the nitrogen atom is about 14 times heavier than the hydrogen atom, the mass ratio is 14:3, thus 1 kg of ammonia contains 176 g of hydrogen."  -- this makes no sense:  it would only be true of 1 mol of ammonia consisted of 1 mol of nitrogen and 1 mol of hydrogen.  But there are *3* mols of hydrogen!  Unless someone can explain otherwise, I'll re-write this example.
--Ross Fraser (talk) 00:34, 21 March 2012 (UTC)
thread_title:  Composition Stoichiometry example in intro makes no sense 

message: How is the stoichiometry matrix extended when nuclear transformations (alpha and beta-decay, nuclear reactions, etc) must be considered? It would be useful to add some details.--188.26.22.131 (talk) 11:04, 26 August 2013 (UTC)
thread_title:  Stoichiometry matrix extension to nuclear transformations 

message: To be honest the quality of this article is abysmal. Its scope is at a high school level, and it seems more suited as a tutorial rather than an encyclopedic page. 
If I have time I will make major changes, but hopefully someone with a high degree of knowledge in Chemistry can help improve this article. It only explains topics in the context of solving elementary chemistry problems, and doesn't really elaborate on their interrelation, and relevance to the field of stoichiometry itself. Additionally a historical component could also be beneficial.
But in my opinion the most appalling issue with this article is the lack of citations, and thereby credibility on the subject matter. Rifasj123 (talk) 02:52, 24 September 2013 (UTC)
thread_title:  Poor quality 

message: The mole is defined as "the amount of substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon-12". http://goldbook.iupac.org/M03980.html
Bearing that in mind, I suggest the ghastly phrase "number of moles" be replaced by the simpler, more accurate word "amount". Thus "the number of moles of methane is 2" becomes "the amount of methane is 2mol". You'd never say "the number of kilograms of potatoes I want is 1", now, would you? Come on - be honest!
90.220.32.65 (talk) 14:16, 14 October 2014 (UTC)
replies: text: Yes, I agree with you, so I have now found and changed 3 occurrences of "number of moles". Dirac66 (talk) 22:49, 14 October 2014 (UTC)
thread_title:  Use the word "amount" 

message: Substituted at 07:06, 30 April 2016 (UTC)
thread_title: Assessment comment

message: Since the example contains 3 reactions that make no transformations, S1 and S2 are the same, and S3, S4, and S5 are the same. A better example that shows more distinct species would be easy to write.   
Could you clarify what you mean that S1 and S2 are the same? The transformation S1 -> S2 could be an isomerization so S1 and S2 would be chemically different, there are many such examples. If you have an alternative example I'd be interested to see it. The main thing is that the example should illustrate the cancelation of stoichiometries as in the second reaction, other than that one can be flexible. Rhodydog (talk) 01:21, 21 January 2021 (UTC)
thread_title:  The example reactions in the "Stoichiometry matrix" section need improvement 

message: The article has a very serious notation problem that also seems to have infected other articles on Wikipedia, so before I start changing things I'd like to ask for consensus.  
According to the IUPAC Gold Book: 
"A chemical reaction of known stoichiometry can be written in general as:
aA+bB+...→...+yY+zZ
For the reaction products Y and Z the numbers y and z are known as the stoichiometric numbers, νY and νZ, for Y and Z respectively. For the reactants the stoichiometric numbers are the negatives of the numbers appearing in the equation; for example the stoichiometric number νA for the reactant A is −a. In other words, the stoichiometric numbers are positive for products and negative for reactants."
The Gold Book reflects common usage here, and this notation is used in textbook treatments of chemical thermodynamics in the fields of chemistry and chemical engineering.
However, the article incorrectly refers to the stoichiometric coefficients si (which are a, b...,y,z in the example above) as being equal to the stoichiometric numbers \nu_i (which are -a, -b ..., y, z). This is important in the theory of chemical thermodynamics and provides the correct pathway for the statement that the change in the number of moles of any species is proportional to the extent of reaction, with coefficient \nu_i. Anyone mind if I fix this? KeeYou Flib (talk) 13:29, 19 April 2021 (UTC)
replies: text: Since no one raised an objection here, I did my best to boldly fix the problem. KeeYou Flib (talk) 04:28, 5 May 2021 (UTC)
thread_title:  Stoichiometric number definition does not agree with the IUPAC Gold Book source cited or with common usage 

message: I believe that the concept of stoichiometric coefficient is most easily and visually explained in the context of chemical equation, so I have retargetted it there. Petr Matas 08:37, 27 June 2022 (UTC)
thread_title:  Target of [[Stoichiometric coefficient]] redirect