Talk:Intensive and extensive properties

From Wikipedia, the free encyclopedia
Jump to: navigation, search
WikiProject Physics (Rated Start-class, High-importance)
WikiProject icon This article is within the scope of WikiProject Physics, a collaborative effort to improve the coverage of Physics on Wikipedia. If you would like to participate, please visit the project page, where you can join the discussion and see a list of open tasks.
Start-Class article Start  This article has been rated as Start-Class on the project's quality scale.
 High  This article has been rated as High-importance on the project's importance scale.
 

Correct term[edit]

Which is the correct term in physics / chemistry:

intrinsic/extrinsic

or

intensive/extensive?

I've seen both usages. The Anome

I have only seen intensive/extensive. Chadloder 09:42 Apr 1, 2003 (UTC)

Extensive makes more sense to me, because it's about something being extended. Michael Hardy 21:29, 5 August 2005 (UTC)

Intensive/Extensive are more more meaningful as these are self-implying words. Intrinsic properties are properties of a system which exist by the very existence of a system, e.g. internal energy. Thus 'intrinsic' is not acceptable in this purpose. The same is for extrinsic. I've not found these usages anywhere.

Intrinsic[edit]

We could use a section on the computing/engineering use of the term "intrinsic". Wouter Lievens 09:26, 4 May 2006 (UTC)

Nevermind, it exists at Intrinsic function.

Removed and kept[edit]

Removed 'vagility' as entirely inappropriate. It is a biological term. If "fragility" was intended, it is a poor example to list here as it is hard to define and measure, and there is no commonly recognised use for such measurements.

On the other hand, I think the discussion on the difference between perception and physical properties should stay here. I am aware that perception is closer to a psychological topic than a physical one - but those who DO confuse the two will never understand the difference if it is tucked away under Perception or Psychology, and the function of an encyclopedia entry is to educate and inform, is it not?

The comment about "pressure" being in the wrong place has been corrected by putting it where it belongs, and removing the comment.
202.61.162.14 12:51, 8 May 2006 (UTC)

'Bulk' vs. 'intensive'?[edit]

I note a merge notice suggesting that bulk property be merged into this article. Is 'intensive property' really a more common usage than 'bulk property'? In quite a few years of science and engineering (with a fair bit of material properties) I've overwhelmingly heard 'bulk'. Some of this might be regional variance, but Googling gets slightly more hits for +"bulk property" than +"intensive property" (787 vs. 739, if you click to the end). ('Extensive' seems to be the antonym of choice in either case.)

Unless there's a reason to favour 'intensive', I would instead suggest renaming this article to bulk and extensive properties, acknowledging 'intensive' and 'bulk' as synonyms, and turning both bulk property and intensive property into redirects. --Calair 02:25, 9 August 2006 (UTC)

On the one hand 'bulk' is commonly used in many colloquial references, not all, whereas intensive is always correct but not always used. For example, no one refers to 'bulk chemical potential', the usual term is simply, 'chemical potential'. The term intensive should be kept, not because it is in common use, but because it is commonly accepted to refer to properties that do not depend on the amount of mater present. — Preceding unsigned comment added by 12.104.156.31 (talk) 19:07, 26 January 2014 (UTC)

Merge[edit]

I just wanted to say that I support the merges suggested on the page. Whether or not this article is ultimately called bulk and extensive or intensive and extensive is pretty unimportant to me. For what it's worth, the terminology being used in my thermo class is intensive. That being said, there is information in the intensive and extensive quantity articles that could be incorporated into this one to improve it. If I get some time here, I'll go ahead and try to add to this one. !jim 02:28, 14 October 2006 (UTC)

Physics favors intensive[edit]

From the standpoint of physics, especially that of the statistical variety, the term "intensive" is most commonly used. Most of the classic textbooks (i.e. Reif) and current work in generalized entropies use intensive/extensive, so such a usage would provide more consistency with established literature. Futher, from a more linguistic point of view, the phrase "intensive and extensive" pair together better than "bulk and exensive"; the change in prefix makes it clear that you're talking about the two sides of a single coin. The colloquial usage of the term "bulk", at least to me, violates what's meant by an intensive/bulk property in its technical usage. I hear bulk and I think "most of, if not, the whole thing" when in fact what we mean is "whatever bit you pick out from the whole thing, no matter how tiny". For that reason I favor a merge to "Intensive and extensive properties". Pgriffin 16:52, 13 September 2006 (UTC)

Fair enough. I agree that 'intensive and extensive' is more aesthetic, and it's common enough to be a reasonable choice. Merge/redirecting to here seems reasonable. --Calair 01:29, 28 September 2006 (UTC)
Indeed, the colloquial concept of a "bulk" property would actually be an extensive quantity. How confusing! Cesiumfrog (talk) 04:26, 9 August 2010 (UTC)

Electrical Resistance[edit]

So, which one is it, an intensive or an extensive property? --No_body 21:07 October 2008 (XYZ) —Preceding unsigned comment added by 76.27.197.169 (talk) 04:07, 18 October 2008 (UTC)

Resistance is extensive, resistivity is intensive. --144.53.226.17 (talk) 05:19, 5 February 2009 (UTC)

As mentioned in almost all classical texts, extensive properties are directly proportional to the mass of the system. Is it good enough to call resistance an extensive property from this viewpoint.. — Preceding unsigned comment added by Memonosij (talkcontribs) 07:16, 27 February 2011 (UTC)

Actually as explained in the section on Counterexamples, resistance is only extensive for resistors connected in series. In general it is neither extensive nor intensive. Resistivity however is intensive as stated above. Dirac66 (talk) 01:14, 7 March 2013 (UTC)

Adding Stiffness[edit]

The link had been one-way.Rainbow-five (talk) 22:56, 23 October 2008 (UTC)

Stiffness does not fullfil the requirements of being extensive since it is not always proportional to the size of the system. E.g. a rod of twice the length has half the stiffness. I have removed it as an example. Ulflund (talk) 18:49, 14 September 2011 (UTC)

Joining systems[edit]

The formula given for intensive properties resulting from combining two systems is correct for some intensive properties but incorrect for many others.

Example: Suppose we have 1 cubic meter of gas A (density 1kg/m^3, mass 1kg) and 1 cubic meter of gas B (density 9kg/m^3, mass 9kg). If we mix them without interaction, we end up with 2m^3 of gas weighing 10kg, i.e. density 5kg/m^3.

However, the formula given says that their density should be (1kg*1kg/m^3 + 9kg*9kg/m^3)/(1kg+9kg) = 8.2kg/m^3, which is obviously wrong.

The formula works if you use the correct definition of "amount" given the context. The correct measure of "amount" to use when combining densities is volume: (1m^3*1kg/m^3 + 1m^3*9kg/m^3)/(1m^3+1m^3)=5kg/m^3. (Every correct formula must at least have dimensional consistency.) Similarly, the example in the article of mixing lead and tin is completely bogus and wrong for the same reason. Combining densities by weight and getting the wrong answer is a mistake I have seen far too often. --66.74.199.221 (talk) 05:58, 25 February 2010 (UTC)

It also fails for temperature in circumstances where the joined substances have different specific heat capacities, and also for things like 'melting point' - the article claims that lead and tin combine without interaction, but the melting point of such a combination will usually be lower than a weighted average would suggest. --144.53.226.17 (talk) 23:42, 4 February 2009 (UTC)

Four years after the above discussion, the section on Joining systems is still in the article. However the joining of dissimilar systems is a much more complex topic than the intensive and extensive properties of a homogeneous system, for several reasons.
  1. As noted above, the weighted mean formula requires choosing a definition of "amount" which is different for different properties, with no obvious general recipe. This makes the application of the weighted formula to other properties problematic.
  2. As hinted in the comment on melting point, the concept of systems "without interaction" is problematic. At the microscopic level all particles interact. Certainly the mixing of solid tin and solid lead to form liquid solder (at the appropriate temperature) indicates that there is an attractive force between Sn and Pb atoms. Perhaps what is meant is something like an ideal solution in the thermodynamic sense, but this does not provide an obvious way of predicting whether or not the weighted mean formula applies in a given case.
  3. This section is unsourced. It is true that most of the article is not properly sourced with inline references, but the other sections at least correspond to a consensus of leading textbooks which can be sourced when someone wants to do it. A modified Joining systems section would need to have sources which explain the problems noted.

For these reasons I will delete this section today. Dirac66 (talk) 02:06, 9 March 2013 (UTC)

Combined extensive properties[edit]

Also, now I look at it, the section on 'combined extensive properties' appears to have a similar problem - the discussion and formula given are not accurate for all the extensive properties listed below it.

This section tells us that 'extensive quantities are homogeneous functions (of degree 1)' with respect to their extensive arguments. Let's define F(w,x,y,z) to be the mass (extensive) of a cuboid that has density w (intensive), and side lengths x, y, z (extensive).

As a homogeneous function of degree 1 with respect to the extensive arguments, F(w,ax,ay,az) 'should' be equal to a*F(w,x,y,z). In fact, it's equal to a^3*F(w,x,y,z). Either the definition of 'extensive property' or the discussion on combined extensive properties is over-broad.

Also, " Dividing one type of extensive quantity by a different type of extensive quantity will in general give an intensive quantity. For example, mass (extensive) divided by volume (extensive) gives density (intensive)." - what if we divide mass by length, giving area, which is also extensive?

I'm not sure whether the problem here is in the formula, or in the definition and examples given for 'extensive'. --144.53.226.17 (talk) 05:40, 5 February 2009 (UTC)

I believe that the section on Combined extensive properties is valid when applied to properties and arguments which are truly extensive. The problem with the above example (mass as a function of density and side lengths) is that length is not an extensive property. For example if two metre sticks are placed together, the length of the combined system depends on geometry - it is 2 m if the sticks are end-to-end, but 1 m if they are side-by-side. This is the same argument as used in the section on Counter-examples for electrical resistance - the resistance of a system of two resistors depends if they are connected in series or in parallel. Length was incorrectly listed as an extensive property during the above discussion in 2009, but this has since been corrected.
So I will keep the section on Combined extensive properties, and I think I will also mention length as a counter-example. Dirac66 (talk) 02:06, 9 March 2013 (UTC)

Templates[edit]

Please use only Wikipedia templates. No reason to copy source code to the page. And please do not add maintenance categories manualy. The appropriate template will do that for you. Debresser (talk) 13:26, 9 February 2009 (UTC)

Assuming this is directed at me, you're under a misapprehension. I haven't copied source code or added categories manually; all I have done is add standard templates with the subst option, which automatically substitutes source when the edit is saved - this makes content somewhat more portable and faster to load.
In modifying those templates, you seem to have removed a couple of my accuracy tags altogether - for instance, in [this edit], tagged as 'deleted unnessecary invisible comments', you actually deleted some visible accuracy tags that were in between two automatically-generated bits of invisible text. I'm reverting on the assumption that you didn't intend to throw the baby out with the bathwater - I have no problem with people fiddling with the template details, but accuracy tags shouldn't be removed without discussion. --144.53.226.17 (talk) 23:47, 9 February 2009 (UTC)

I removed those because I added the {{unsourced}} template at the beginning of the article in stead. Being that there are no references whatsoever, that seems to be more inclusive than what you do.

You also add various things between <!-- --->. That seems unnecessary to me.

You add the {{fact}} template in such a way that adds this article to the Category:Articles with invalid date parameter in template. Which is what I came to fix initially. So at least remove that template, please. Especially since you have it between <!-- ---> anyway.

Basically my problem with your revert is that you add a lot of unnecessary things to the article source that make more trouble than they do good. Debresser (talk) 00:38, 10 February 2009 (UTC)

I think you've mis-parsed the code there. The templates were not within <!-- ---> - if they were, they wouldn't be adding the article to a category.
As an example, look at the first part of this edit. What I added, directly after the link to buoyancy, was {{subst:citeneeded}}
This gets automatically expanded to: <!-- Auto-generated comment 1 ---> {{Actual template code}} <!-- Auto-generated comment 2 ---> The template code is between two invisible comments (both auto-generated by template substitution), but it's not inside either of them (which is why it can work at all). Instead of removing a comment, your edit actually removed the template code sandwiched between those comments, while leaving the comments themselves untouched.
I'm not sure why this is causing problems with the date parameter; a standard template shouldn't be doing that, with or without use of subst. I've replaced the substituted templates with non-substituted; let me know if that's fixed the problem.
Agreed that the whole article needs much better sourcing. However, the bits that are demonstrably wrong are a bigger problem than the rest of the article, and should be specifically flagged as untrustworthy. --144.53.226.17 (talk) 02:01, 10 February 2009 (UTC)

That looks better esthetically, that's for sure! And I agree with you that it was better the way you did, tagging the problematic sections specifically. I'll add the {{unsourced}} template as well, since the article as a whole needs references too.

This didn't solve my problem though, for an obvious reason. You added the category manually at the end of the article in the categories part.

I've searched for a certain line on some page, but can't find it. The closest I found is Category:Hidden categories. What it said over there, and is implicated on Category:Hidden categories, is that one should not manually add maintenance categories. I made this point to you before, but I'd have liked to show you where it says so.

I'll remove the manually added categories. I'm sure that'll be fine with you, as I don't touch the article itself. That'll still keep the article inside the necessary categories because the templates do that for you.

I am a relatively new editor, but I have done quite a lot of work with categories, templates and maintenance. Most articles I've seen so far add templates the way we have it now. If I weren't afraid of unintentionally saying a lie, I'd say "all articles I've seen so far".

Anyway, I thank you for being willing to consider my problems, as they are not pertinent to the article itself (and I don't pretend to be an expert in that field), but rather come from general Wikipedia housekeeping, and I am basically intruding on this article. Debresser (talk) 08:23, 10 February 2009 (UTC)

I found it. This is what I wanted to show you Wikipedia:Categories#Maintenance_categories. Did you have a look at the article? It worked out fine. Debresser (talk) 08:40, 10 February 2009 (UTC)

"You added the category manually at the end of the article in the categories part" - this is not correct. As I've said above, I have not manually added this article to any categories. The last of my original edits is here - if you check the source code, you'll see that the only category listed at the bottom of the page is Category:Physical property.
Because I used the subst option, those categories were automatically added within the expanded accuracy templates, which is as it should be - if you template without using subst, you end up with the exact same result, just that it's hidden from somebody reading the source code. Unfortunately, after my edits, two bot edits moved those category tags out of the accuracy templates where they ought to be, and down to the bottom of the article diff. As a consequence, when I replaced the substituted templates with non-substituted versions yesterday, I missed cleaning up the new categories that had been moved to the bottom of the article - thanks for catching those and removing them.
"Most articles I've seen so far add templates the way we have it now" - substitution is more commonly used in things like user talk namespace (and I think that's where I got into the habit of using it) but it is also used in article space. For example, see this version of 'Little Theatre of Winston-Salem', which begins with a substituted copyvio tag. See discussion at WP:SUBST for more on this; in brief, some templates should always be substituted, some should never be substituted, and many (including the ones used here) should be usable either way. Though given the amount of trouble it causes, perhaps I'll go back to using non-substituted as the default. --144.53.226.17 (talk) 23:40, 10 February 2009 (UTC)
Now I understand how they got there. That's a good reason not to practise substituting in articles. :) In short, it's been a pleasure coming to mutual understanding with you, and fixing some small isues with the article on the way. :) Debresser (talk) 00:36, 11 February 2009 (UTC)

Ratios of extensive properties[edit]

It follows, for example, that the ratio of two extensive quantities is an intensive quantity

So the ratio of mass to length is an intensive quantity? Or the ratio of mass to resistance? 72.75.67.226 (talk) 04:23, 14 October 2009 (UTC)

Good questions. The answer is that "extensive quantity" has been incorrectly defined in this article, and some of the examples are incorrect. Atkins and de Paula ("Atkins' Physical Chemistry", 8th ed 2006, W.H.Freeman, p.31) define an extensive property as a property that depends on the amount of substance (NOT the size) in the sample. Still more correct I think would be *proportional* to the amount of substance (under given conditions such as T and p).
So for the current list of examples, the correct extensive properties are mass, volume, entropy, enthalpy, energy, stiffness (I think) and particle number. Length is not extensive since two samples of the same amount of the same substance in the same conditions can have different lengths. The same is true of electrical resistance. And texture is not even a quantity with a single value for a given system.
The list of intensive examples also needs more thought. Lustre?? Magnetism?? Odor?? Dirac66 (talk) 17:31, 14 October 2009 (UTC)
The official IUPAC definition is found in the IUPAC green book at http://www.iupac.org/publications/books/gbook/green_book_2ed.pdf (see p.16). It says "A quantity whose magnitude is additive for subsystems is called extensive" [examples m, V, G]. "A quantity whose magnitude is independent of the extent of the system is called intensive" [examples T, p, μ]. This is equivalent to Atkins and de Paula but I think more precise. Again L and R are not extensive: L = L1 + L2 only if the 2 objects are placed end-to-end but not in general, and R = R1 + R2 only if the 2 resistances are connected in series but not in general. And again texture is not a quantity. Dirac66 (talk) 02:57, 15 October 2009 (UTC)
Well, odor is intensive. just... things like density are better examples...Nibelhim (talk) —Preceding undated comment added 15:16, 19 December 2009 (UTC).
I have now added electrical resistance as a counter-example, with an explanation of why it is neither extensive nor intensive. Dirac66 (talk) 15:36, 8 November 2011 (UTC)

Quality vs. Quantity[edit]

I am amazed that there is only one mention of the concept of quality in this article, short as it is -- and it's practically an aside, at that. Of course, the article also reeks of bourgeois reductionist logic, and not dialectical-materialism. Not unusual for Wikipedia's science topics. —Preceding unsigned comment added by Pazouzou (talkcontribs) 17:27, 14 June 2010 (UTC)

Browser-dependent list layout[edit]

Today Kbrose changed the two lists of example intensive and extensive properties to a 3-column format. This is a good idea for long lists of short items, except that with Internet Explorer 7.0 it doesn't work and the lists still appear as 1-column. For Mozilla Firefox 3.6 on the other hand it does work and the lists look much nicer. I have no idea why the difference. Dirac66 (talk) 18:02, 13 August 2010 (UTC)

In economics[edit]

Are these terms used in economics, or just in the physical sciences? For example, the difference between gross domestic product (GDP) and GDP per capita resembles the difference between mass and density. --Damian Yerrick (talk | stalk) 23:16, 18 February 2011 (UTC)

I think these terms apply equally to economics, for example: Q (quantity per period) and p (unit price). Their usage may not be widespread but p-Q is no different from the natural pairs p-V or T-S. I think a comment to this effect should be added. Robbiemorrison (talk) 11:31, 20 August 2012 (UTC)
The question is whether there are at least some economics textbooks or articles which do in fact use the terms. If so, then we can cite them as sources. If not, then there may be a formal mathematical similarity, but mentioning it would be original research which is not supposed to be in Wikipedia. See WP:OR for the policy. Dirac66 (talk) 02:05, 22 August 2012 (UTC)

Distinction from perceptions[edit]

The Intensive and extensive properties#Distinction from perceptions section uses color as an example of something related to an extensive property which it is not. I would correct this but cannot think of any preception related to an extensive property. I think this section should instead be removed. Ulflund (talk) 19:09, 14 September 2011 (UTC)

This section is really more about what is and is not a physical property, rather than about the terms intensive and extensive. I propose to move the section to the article Physical property. Then the mentions of intensive and extensive can be deleted from the section, since they are not exactly correct. Dirac66 (talk) 03:03, 15 September 2011 (UTC)

Invariant mass in special relativity[edit]

According to today's edit by Incnis Mrsi: An extensive quantity is usually additive ... But there are extensive quantities for which it is not the case: invariant mass in special relativity is not additive.

I understand that invariant mass is not additive when one subsystem is moving at relativistic velocity with respect to another subsystem. However since an extensive quantity is defined as one which is additive, the consequence is that invariant mass is also not extensive under these conditions. So it is incorrect to say that invariant mass is an extensive quantity which is not additive. In fact it is both additive and extensive when relativistic effects are ignored, and it is in general neither additive nor extensive in special relativity. Dirac66 (talk) 03:16, 5 February 2012 (UTC)

Sorry, I do not understand your point: do you see invariant mass as an example of quantity not extensive nor intensive? Is there a definition of an intensive quantity somewhat broader than "a quotient of two extensive quantities"? Incnis Mrsi (talk) 07:50, 5 February 2012 (UTC)
Yes, invariant mass is an example of "neither extensive nor intensive". As explained in the intro, intensive means independent of the system size, which is clearly not true of invariant mass. The last section of the article (Counter-example) does explain that there are properties which are neither extensive nor intensive, using electrical resistance as one example. Invariant mass would be another counter-example, and one could find many others. Dirac66 (talk) 12:26, 5 February 2012 (UTC)
Well, I do not insist on my interpretation. Move it to counter-examples with appropriate explanations (probably, your English is better than mine). Incnis Mrsi (talk) 12:55, 5 February 2012 (UTC)

Be careful what values you put there as intensive or extensive[edit]

I removed velocity and acceleration. Although for a rigid system that does not rotate, it's true that they are intensive, it's not true in general. For a rotating stick, the speed of the subsystems (for example, the tip of the stick) depends on the size of the stick. You add more length to it, you get more speed, if it's a constant rotation. Similar considerations go for acceleration. — Preceding unsigned comment added by 79.119.58.54 (talk) 20:58, 21 March 2013 (UTC)

Are you saying that the same property can be chimeric? sometimes like this sometimes opposite??? that is an example how misused and misunderstood this concept of intensiveness is and actually even shifted to overlap with additive properties (someone just annihilated this concept and renamed additiveness to extensiveness or created a synonym). — Preceding unsigned comment added by 134.7.193.46 (talk) 13:06, 2 August 2016 (UTC)

Spatial variability - too soon.in article[edit]

Today the point that intensive properties can vary spatially was added as the second sentence of the article. This point is true but I think it has been mentioned too soon, since it only applies to local (not global) equilibrium and is not essential to a basic understanding of the concept of intensive variable. I suggest moving this point to the section on Intensive properties, perhaps at the end of the intro to that section just after noting that certain properties are not relevant to extremely small systems. Dirac66 (talk) 18:41, 8 April 2013 (UTC)

Counterexamples are not nonsense[edit]

Today Kbrose deleted two of the three counterexamples with no explanation other than an edit summary saying "remove nonsense examples from 'counterexamples'". For the first counterexample, electrical resistance (R), if you believe the reasoning is incorrect, please explain why. If you believe that R is so obviously not extensive that it does not to be explained, I would point out that prior to Sept. 2011, R was included in the article as a supposedly extensive property. After removing it on 14 Sept. 2011, I decided on 8 Nov.2011 that it would be useful to some readers to explain why it is not extensive.

For the second example, length, I note that Kbrose has also inserted length into the list of extensive properties. Again this is contradicted by the reasoning just deleted from the Counterexamples section, so please explain why this reasoning is incorrect.

I am going to restore these two counterexamples. Please do not remove them without adequate explanations. Dirac66 (talk) 15:29, 24 April 2013 (UTC)

Frankly, you have to be joking. This can only happen on WP. You are making a laughing stock out of WP and yourself. These examples are ridiculous. Take any text book on physics and it will explain it, and indeed list length as an extensive property. How can length not be extensive? It is one of the simplest properties. If length is not extensive, then volume isn't either. Length is the measurement of a one-dimensional space, if you had a second subsystem, it can only be the sum of the lengths. If you are adding another yard stick in parallel to a first, you are not adding anything to the property length, in this case would you call the property 'width' extensive? If length is not extensive and width is, then please tell us how the properties width and length differ so fundamentally? The same applies to resistance. switch two resistors in parallel vs. in series is not a valid comparison, albeit seemingly the amount of material is increasing in both. But that is clearly not the important aspect now, is it? Resistance is extensive and resistivity, i.e. 'specific' resistance, is intensive. The entire section of 'counterexamples' should be removed. Just what is a 'counterexample' anyways? Kbrose (talk) 00:10, 25 April 2013 (UTC)

I have deleted the entire section, it is pure fiction. If you want to include stuff like this section in WP articles, please provide adequate reliable sources to back your claims. Without that, it is not even worth reasoning here. Kbrose (talk) 00:46, 25 April 2013 (UTC)

Dirac, in the length example, you cannot use a one-dimensional system when adding the sticks length-wise, and then expand the system to another dimension perpendicular (width) when placing it along-side. You have to combine two identical systems to form the new larger one. In one dimension as for length, you can only add two subsystem along the same axis. Two systems with orthogonal spacial coordinates (lengths) cannot be combined without changing the dimensionality of the problem and then it is a problem of area, not length. The same applies in extension to volume of course. The resistance example is similar. Resistivity is per unit length through unit area, and resistance is the extensive version. A parallel resistor adds cross-sectional area of conductance path, while a series arrangement adds length of conduction path. Hope this get's you started in the right direction. Kbrose (talk) 05:06, 25 April 2013 (UTC)

Source for counterexamples[edit]

I have now found a reliable source for some of the arguments in the recently removed Counterexamples section. A paper in J.Chem.Educ. by Otto Redlich, known for the Redlich-Kwong equation of state. He has an example of galvanic cells connected in series or in parallel, analogous to the example of electrical resistances. So I have rewritten the section with a new title and used the example of galvanic cells. I believe that the case of electrical resistance is entirely analogous but agree to use the example which is explicitly mentioned in the source article.

As for length being extensive, the physical chemistry texts I checked just give 2-3 basic examples of extensive properties such as mass and volume, plus thermodynamic properties. Yes, length is extensive IF one only considers a one-dimensional space. But my universe has three dimensions and displacements in the other two dimensions are possible also, as are rotations. So I will leave length in the list, but add in parentheses (for one-dimensional systems).

Finally for invariant mass I have no source, although the argument in the deleted section does appear to be correct. If someone finds a reliable source we can restore it. Dirac66 (talk) 22:46, 25 April 2013 (UTC)

This section is still wiki-science. With enough acrobatics you can come up with a lot of things that fall outside of the definitions. That doesn't make it notable or even correct. Clearly there are a lot of mathematical functions, like the square root, that would render the concept meaningless. Clearly the square root of volume is not a new physical quantity, even if you devise a measurement that provides that reading. Volume is still volume and it does not change the property. The common understanding these days is that additive in extensive applies only to subsystem that don't interact. The article cites IUPAC sources which make it clear. Your galvanic cells or the resistors clearly do interact and therefore one must consider the dimensionality of the problem in detail to arrive at the correct solution that both are indeed extensive properties. Clearly they are not bulk properties.

The property length in physics is always one-dimensional whether the space is linear or curved, and the comment is superfluous. This is not the common language 'length' that is simply the longest dimension of an object. You have to really have a weird point to push onto others to make such comments. Kbrose (talk) 16:26, 26 April 2013 (UTC)

Diamond example in introduction - isn't gravity irrelevant?[edit]

Near the end of the introduction, the article states:

For example, when gravity may be assumed constant, the ratio of the extensive properties mass and volume, the density, is an intensive property

I'm not a master of physics or anything, but from my understanding, isn't gravity irrelevant when discussing the ratio of mass and volume? Constant gravity would only be required if it were the ratio of weight and volume, correct? If somebody can confirm this I'd like to change the sentence to read:

For example, the ratio of the extensive properties mass and volume, the density, is an intensive property

I think that just about any physics article is improved when gravity doesn't rear its ugly head. Dataxpress (talk) 03:52, 18 February 2015 (UTC)

Gravity has two roles here. First, weight = mg so increasing gravity increases the weight associated with a given mass, as you realize. But there is also a second effect which becomes important for large (say planet-sized) objects - gravity pulls the mass together so that at higher gravity, the mass density itself (and not just the weight density) increases. For laboratory-sized systems the variation is negligible, but it does become important in planetary science and astronomy. Dirac66 (talk) 01:43, 19 February 2015 (UTC)
Ah, got it. Makes sense. Thanks for the explanation. Dataxpress (talk) 21:51, 7 March 2015 (UTC)

This page is a mess in Mozilla Firefox...[edit]

In essence, towards the bottom of the page, it becomes an absolute clusterf*ck that is barely legible. Can someone fix this? 98.220.186.209 (talk) 17:44, 18 February 2015 (UTC)

Fixed. The problem was that the previous edit by 193.1.30.2 deleted the colend (column end) parameter at the end of the list of examples of intensive properties. This parameter tells the system that the list of 3 columns is finished, so without it the system tried to put the whole rest of the article into a long list with 3 columns which looked terrible as you say. I have restored the missing colend. Dirac66 (talk) 00:56, 19 February 2015 (UTC)

Extensive[edit]

In my opinion, the example of the amount of heat required to melt ice is a poor one because heat is not a property at all; rather, it is a measure of energy transferred. This has the potential to cause confusion between these two distinct concepts. The description is not exactly wrong since it alludes to heat capacity vs specific heat capacity, but it does not use this terminology. I think an alternative example may be more useful.

I also have an issue with the statement that dividing two extensive properties gives an intensive one. What if I select, say, entropy and enthalpy? I think the resulting "property" would be useless (particularly since those properties are measured against an arbitrary datum)? In forming an intensive property this way, are there any candidates for the denominator other than mass, amount of substance (moles) and volume?

129.97.144.230 (talk) 15:29, 27 July 2016 (UTC)

First I have moved this new thread to the bottom of the Talk page. It is true that heat is in general a process function, so I have specified heat required at constant temperature and pressure. Under these conditions the heat required is a well-defined property called the enthalpy of fusion.
As for dividing two extensive properties, the article only claims that the quotient is intensive and does not claim that it is necessarily useful. Enthalpy divided by entropy has units of a temperature which may be useful in some problems. For the case of melting ice again, enthalpy of fusion divided by entropy of fusion is melting temperature, which is certainly useful. Dirac66 (talk) 18:52, 29 July 2016 (UTC)

Some people confusing additiveness with extensiveness-intensiveness[edit]

why all this classification of intensiveness-extensiveness was switched to additiveness-nonadditiveness??? original concept was to have additional property to this by telling witch one is space related and witch one is not (meaning time related), that is why changes in volume was chosen as a central idea (and the discrimination factor)!!! — Preceding unsigned comment added by 134.7.193.46 (talk) 12:57, 2 August 2016 (UTC)