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Temperature as a measure of Heat?

Since the common concept of heat is its association with 'hotness' or 'coldness' i.e. temperature, surely this should be explained in the opening section as well as the role of temperature difference? --Damorbel (talk) 16:45, 8 March 2013 (UTC)

The sentence you added is incorrect according to the standard, technical definition of heat, and directly contradicted the paragraphs before and after it in the article. It's also incorrect according to the non-technical, intuitive definition (how hot something feels when you touch it or stand close to it is only partly determined by its temperature). Waleswatcher (talk) 15:39, 10 March 2013 (UTC)

Currently the article says:-

Heat flow from hotter to colder systems occurs spontaneously

which makes heat independent of temperature, it would also make heat a conserved quantity. Would you care to confirm that this is what you mean? --Damorbel (talk) 21:27, 10 March 2013 (UTC)

Heat is not a conserved quantity, nor does it make sense to say that it is "independent of temperature" (I'd say that's on the wrong end of not even wrong). So no, that's not what I mean. Waleswatcher (talk) 22:15, 10 March 2013 (UTC)

If heat is not independent of temperature, why does the article, in the opening statement, say " Heat flow from hotter to colder systems occurs spontaneously, "? This statement makes the position (of the article) very clear, that heat is proportional to the difference in temperature, i.e. very clearly not a function of temperature. Is this correct? --Damorbel (talk) 06:48, 11 March 2013 (UTC)

definition of quantity of energy transferred as heat

There have been countless electrons spilt here on the definition of quantity of energy transferred as heat for this article. I hope I may be forgiven for saying some more about it. I have to say that I think my understanding has improved over the years. In particular I have to say I was partly mistaken in my strictures upon Count Iblis, and I would like to say I am sorry for the times when I went over the top. The matter is not one-sided. I made much of the idea that temperature has to be definable for heat to make sense. I would now speak more carefully. Count Iblis wrote: "Work doesn't have to be mechanical work. The work done by a system is defined as the decrease in the internal energy of a system due to the change of its external parameters." This is one way of seeing things. I would say that in the Carathéodory story, the decrease of internal energy of the system is defined as derived from the measured adiabatic work needed for the change of state. In the Gibbs story, one postulates directly the existence of the internal energy and doesn't derive it from work; of course still one can specialize to a closed system and then derive the work from the postulated internal energy.

I will now try here to say how I think quantity of energy transferred as heat should be defined here.

Quantity of energy transferred as heat is a term of thermodynamics that refers to a specified change of state of a closed system. The initial and final states of the system have defined temperatures and pressures. The quantity of energy transferred as heat is defined as a difference between two quantities of energy transferred as work. One of those quantities is the amount of adiabatic work needed to go between the initial and final state of the change; it refers to the specified change of state only through its initial and final states. The other is the amount of work done by the system on its surroundings during the specified change. This work is in general not adiabatic, and in general includes pressure-volume work and isochoric work. It depends only on the time course of the values of the external variables, including those such as the forces exerted by the surroundings on the walls of the system. How those forces are specified is important. If the work is mediated by a piston, then the external forces that determine the motion of the piston need to be defined. The piston may be driven by a rod. Then the force exerted by the rod on the piston must be specified. The external pressure on the external surface of the piston must also be specified throughout the course of the process, though it might be neglibly small. (I formerly insisted that if that pressure could not be defined during the course of the specified process, then the work could not be defined; that is true. Moreover I insisted that when that pressure was not defined, the external temperature was most likely also not defined. Therefore, I argued, when the external temperature was not defined, the work was not defined. I went too far there. It might sometimes be that the external pressure is defined while external temperature is not; still the work would be defined, as Count Iblis pointed out.) There is no requirement by definition that the external and internal temperatures and piston pressures be equal during the course of the process, but respectively they must be equal in the initial state and in the final state, which are respectively required by classical thermodynamics to be in thermal and mechanical equilibrium with the surroundings.Chjoaygame (talk) 10:44, 12 March 2013 (UTC)

Chjoaygame you write:-

Quantity of energy transferred as heat is a term of thermodynamics that refers to a specified change of state of a closed system. The initial and final states of the system have defined temperatures and pressures. The quantity of energy transferred as heat is defined as a difference between two quantities of energy transferred as work.

This statement is too restrictive. If the changes result in The initial and final states of the system hav defined temperatures and pressures then you will be dealing with a system where heat is conserved, your argument does not allow for potential energy. The perfection of an ideal gas matters not, even if such an ideal existed, you would still have to allocate some stress energy to the walls of the container. --Damorbel (talk) 11:41, 12 March 2013 (UTC)

what page in the source?

This edit proposes that a sentence about conduction, cited in the article, appears on page 1 of Partington 1949. In the copy I have here it appears on page 118, and not on page 1. Perhaps the creator of the edit would very kindly tell how he is accessing the source?Chjoaygame (talk) 08:25, 13 March 2013 (UTC)

I've restored this question because it is highly relevant.

In the article all the references are made to a text book by J. R. Partington:-

An Advanced Treatise on Physical Chemistry Vol 1: Fundamental Principles (ISBN 0471668176 )

This book is difficult but not impossible to find. It is a text book thus not automatically a reliable source.

Partington wrote another book:

A Text-Book of Thermodynamics; (With Special Reference to Chemistry)ISBN1152051253

First published in 1913 - it can be found on line. This book is far more compact than "An Advanced Treatise..." and serves quite well as an introduction to thermodynamics but it is only a text book.

Partington was a respected teacher of (Physical) chemistry but did not make any contributions to science as did Clausius, Boltzmann, Planck, Maxwell and others, works by these pioneers are freely available and have the great merit of allowing the reader to follow the intellectual developement of the subject, they are far superior to text books published by teachers. If it is absolutely necessary to reference a text book the relevant passage should be cited as fully as possible, a mere reference to the entire book serves no purpose. --Damorbel (talk) 09:48, 13 March 2013 (UTC)

Convection?

From the beginning paragraph "heat is energy transferred from one body to another by thermal interactions." Convection therefore is not a method of heat transfer as the heat is retained by the body and the body itself moved. Strictly speaking convection is a special form of conduction - conduction in a fluid. FlipC (talk) 10:53, 14 March 2013 (UTC)

Interesting. First a trivial point. The clause "Heat is energy tranferred from one body to another by thermal interactions" is chatty but hardly informative. The source for it is Reif, but it is not an exact quote from Reif, who writes of "purely thermal interactions". Without some further definition, "thermal interactions" is a pleonasm for 'heat'. It says nothing that 'heat' does not say. So it is not useful to use the word 'therefore' when interpreting that lead clause.

Now to the substance of your comment. Is convection a form of heat transfer that should be recognized in this article? In the lead of this article? We have one editor who says it is, and I suppose there will be others. You seem to have two views, that it is not (because "the heat is retained by the body and the body itself moved"), and that it is (because it is "conduction in a fluid"). At present I think that in general, in the present context, one should not simply say that convection is a form of transfer of energy as heat, but I think that under some conditions, convective circulation may be regarded as a form of transfer of energy as heat. In any case, convection is a conceptually more complex phenomenon than either thermal conduction or radiation. The exact mechanism of heat transfer is not an easy thing to define. How should this be expressed in the lead?Chjoaygame (talk) 20:49, 14 March 2013 (UTC)

If we use the term "thermal interactions" then one could include convection. On the other hand if we treat heat as a net exchange of energy from one body to another then we can't. When I use the term "conduction in a fluid" I refer to the actual exchange mechanism which leads to more complex actions due to the ability of the bodies to move. IOW conduction (and to a lesser extent radiation) in a fluid has greater ramifications than such in solids, but is not a new mechanism in its own right. Do we treat "transfer" as synonymous with "exchange" or with "movement"? FlipC (talk) 10:00, 22 March 2013 (UTC)

For me, 'thermal interaction' is not a well defined term. I think it is sloppy and evasive phraseology, and its presence there in the article is a regrettable blemish. I do not try to fix every blemish, not even very regrettable ones, because such an action can easily result in a fierce backlash that makes the 'fix' badly counterproductive.

I am unhappy to have had to look up 'IOW'.

I suppose there are many meanings to 'transfer'. I use it in this context to mean passage of a transiently conserved amount of an extensive quantity, such as mass, internal energy, or entropy, from one spatial compartment to another. I think it is synonymous with neither 'exchange' nor 'movement'.Chjoaygame (talk) 03:05, 23 March 2013 (UTC)

The Reif reference is to a textbook, so may well be unreliable. It's definition of heat is inconsistent in that it confuses heat and heat transfer. This is self contradictory, so not even wrong! --Damorbel (talk) 15:38, 23 March 2013 (UTC)

It would appear that the process of convection would not be a meaningful process for heat energy transfer because the environmental conditions related to the process are too variable and also not related to the fundamental properties of the heat content materials. I would think that the term heat would relate to the energy content of the concerned materials and is supposed to be equal to a function of their mass value plus their kinetic energy content.WFPM (talk) 19:32, 23 March 2013 (UTC)

WFPM, you write:-

too variable and also not related to the fundamental properties

do you have a source for this? I suggest your assertion is not clear, would you care to explain it further? --Damorbel (talk) 20:40, 23 March 2013 (UTC)

Well alright I've been asked to estimate the heat transfer of say an air conditioner but I couldn't do it because I couldn't determine the convective heat loss possibilities of the system due to the variables. I know how to get it down to practically zero by vacuum packaging it but that wasn't the question. And I could reduce the radiation heat losses with reflective external packaging but that wasn't the question either. So the question involves more than one independent set of physical conditions and process factors that doesn't let the question be meaningful. Only estimates can be made related to the specific properties and materials under consideration. That's the subject matter of thermodynamics which does a pretty good job at approximating the answers to the thermodynamic questions. And it's certainly not an exact science when I studied it in the sliderule days.WFPM (talk) 01:48, 24 March 2013 (UTC)

I understand from what you write that the theory of thermodynamics is inexact because of the difficulties in applyng it to airco? Almost all thermodynamic theory applies only to sysytems at or near equilibrium. It is usual to separate a complex thermodynamic system, such as air conditioner or rocket motors, into separate subsystems; a compressor, heat exchanger etc. for airco; combustion chamber and expansion nozzle for a rocket; and solve them individually. In this way the problem becomes more manageable but may well require a number of iterations to achieve a satisfactory result.

I am interested to discover if you consider these dfficulties with heat transfer calculations raise questions about the theory of heat. --Damorbel (talk) 06:36, 26 March 2013 (UTC)

The answer is Yes! The theory of heat is like the theory of energy, which is, What is it? And after we agree what it is, then we can talk about how it is moved from one place-situation to another. And heat, as far as I know, is just a physical condition of matter. Clerk Maxwell studied the problem of heat distribution in a gas and come up with his velocity distribution equations. That makes sense. But the transfer of heat is filled with lots of contingent conditions, like convection variables, that don't have anything to do with anything other than the considered process. And I think the subject matter related to the word heat should be as to what it is, and then you can go of on a tangent into some way it can be transferred and otherwise managed. But you seem to want to put all those subservient subject matters under the umbrella of the subject matter of heat, I guess because you want to worry about its transfer as part of the theory of its existence. Thermodynamics is an interesting (and complex) subject matter. But it involves a lot more variables than the subject of heat. And you're trying to crowed all that into your heat subject matter. I can see the word thermodynamics getting involved in a lot of stuff but the word heat should be limited in its definition.WFPM (talk) 16:19, 26 March 2013 (UTC) That means that when you say heat I think you're talking about the noun heat Calor)and not about the verb to heat (Calentar).WFPM (talk) 17:56, 26 March 2013 (UTC)

You write:-

The theory of heat is like the theory of energy

One of the features that distinguishes heat from energy is that energy is a conserved quantity, whereas it is a fundamental aspect of modern physics is that heat is not a conserved quantity. Is this included in your questions " about the theory of heat "? --Damorbel (talk) 06:32, 27 March 2013 (UTC)

A gas has heat due to the motion of its particles. I don't see how you can reduce the quantity of one of them without reducing the quantity of the other. Under a constant volume condition a quantity will remain at a certain temperature condition (with a certain temperature and heat content) unless something (Energy) is lost, in which case both the temperature and particle velocity will reduce.WFPM (talk) 19:13, 27 March 2013 (UTC)

The temperature of a solid rises when energy is added, the rising temperature means that the atoms (or molecules) of the solid vibrate with increasing amplitude until, at a particular temperature, the (crystaline?) bonds holding it in solid form, begin to break, it is melting.

Continuing to add energy breaks more bonds without increasing the temperature as more of the solid melts. Finally the solid is completely melted and the temperature starts rising again, with the molecular motion of the liquid increasing further. The amount of energy needed to melt (fuse) a solid is properly called the enthalpy of fusion but is popularly (and mistakenly) called the latent heat of fusion.

From this you can see adding energy can either raise the temperature i.e. increase the heat, or melt the solid when its temperature does not rise. This is similar to boiling - energy is added to a boiling liquid without raising it's temperature; this energy is called the enthalpy of vaporization, often (improperly) called latent heat of vaporization.

Enthalpy is a more accurate term than latent heat because it represents potential energy, the energy of the bonds holding atoms or molecules together in a solid, whereas heat is, as you noted, the kinetic energy of atoms and molecules. --Damorbel (talk) 21:30, 27 March 2013 (UTC)

Yes, but now you're talking about the amount of motion in a different category of phase of a material. So the particles acquire more energy and move faster and eventually break the bounds of stability of the phase. That's a detail. It's still matter in motion. And after we get to the gas phase, the problem settles down to what can happen to 22.4 liters of a gas at standard pressure and temperature. And Thermodynamics is where you worry about the details of that. And I guess I don't know enough about the fine points of Thermodynamics terminology definitions to be able to discuss those points of issue.WFPM (talk) 23:22, 27 March 2013 (UTC)WFPM (talk) 23:14, 27 March 2013 (UTC)

You write:-

amount of motion in a different category of phase of a material

Are you saying that this influences the relation of particle energy and temperature? If this was so there would be different Boltzmann constants for solids and liquids.

The argument I was putting is that both enthalpy (energy) of fusion and vapourisation are forms of potential energy arising from intermolecular forces, this is the conventional viewpoint and has been for a long time. Calling them (latent) heat of fusion or vapourisation introduces confusion between kinetic energy (heat) and potential energy. --Damorbel (talk) 07:30, 28 March 2013 (UTC)

Yes it's fascinating to note that we have this interrelationship between energy and temperature during the phase periods, and then the hiatus while the atom sorts out its internal energy storage (internal construction) problems. But heat energy is still matter (mass) times velocity squared whether you can see it or not. In the CRC handbook you have the Calorie defined in terms of their favorite energy unit the Joule as being 4.1868 joules. And the joule is 10 million ergs. So if you had a balloon with some water and you put heat in it and expanded it and if you were outside it and didn't have the buoyancy of the air and couldn't see its size change you wouldn't note it to be any different with all that additional heat energy. But since our concept of temperature is related to the heat energy mass times velocity squared/2 values, we soon get into astronomical temperature values when we get into the presumed velocities of the Big Bang theory. And at that level their value isn't telling us much of anything.WFPM (talk) 17:41, 28 March 2013 (UTC)

Needs Revision. Contains a fundamental blunder.

The following sentence is wrong: " Heat ... is synonymous with heat flow and heat transfer." Heat is not synonymous with heat transfer. That statement is risible. I also commented on the talk page of the Heat Capacity article. "Freeman Dyson in writes: Heat is disordered energy." ← this is from my 1966 Physics textbook (Halliday & Resnick Pts I & II pg 640). Heat transfer is a process, heat is a type of energy. If someone wants to make an argument that the process is the thing, then they should do so explicitly, but NOT in the introduction. The logical problem I see in making this claim, is that multiple different processes in an isolated system can lead to identical heat energy transferred (but not identical final state, obviously). The process is not the (abstract) thing.173.189.78.236 (talk) 01:46, 18 May 2013 (UTC)

Heat is not a type of energy, it is a type of energy transfer. Heat(ing) is responsible for a change in the internal energy, it is a process by which the internal energy is increased. Similarly, work is not a type of energy but rather a type of energy transfer, a process by which the internal energy is increased. For a given internal energy, there is no way to divide it up into heat energy and non-heat energy, or work and non-work energy. The logical problem you pose is unclear. Can you give a concrete example? PAR (talk) 02:09, 18 May 2013 (UTC)

On the physics here, I agree with Editor PAR against Editor 173.189.78.236. In thermodynamics in its strict sense of language, "Heat is not a type of energy, it is a type of energy transfer"; the above comment of Editor 173.189.78.236 does not recognize this. The comment of Editor 173.189.78.236, that "The process is not the (abstract) thing", is logically muddled; it seems to make the mistaken assumption that 'heat' in thermodynamics is an enduring physical object; it is not, it is only a label for a kind of process. The quote from Freeman Dyson is couched in loose rhetorical language, and should not be read as strictly logical.

Nevertheless, in relation to the use of language, Editor 173.189.78.236 makes a reasonable point about in the sentence that he quotes from the Misplaced Pages article. The sentence that he quotes is worded so as to be open to being misread, because it does not make it clear enough that it refers narrowly to a very specific language usage, that of thermodynamics in its strict sense.Chjoaygame (talk) 22:48, 18 May 2013 (UTC)

The observation by editor 173.189.78.236 that Heat is not synonymous with heat transfer is entirely correct, heat is measured in joules (J), heat transfer in joules per second (J/s). Only the truly ignorant could possibly see these as somehow "equivalent". I propose that the statement (and its consequences in the article) be deleted.

Similarly I am replacing my contribution, removed here by User Cburnett. My contribution drew attention to the fact that it is only the energy that is equivalent in thermodynamic systems; bundling kinetic and potential energy in the same category, which is what the " = " does, is a mathemamatical simplification of physics much too far, clearly leading tho the kind of confusion noted by editor 173.189.78.236. --Damorbel (talk) 06:20, 27 May 2013 (UTC)

Further to the statement:-

Heat is not a type of energy, it is a type of energy transfer by editor PAR.

If heat is "not a type of energy", then just what is it?

Saying that it is "not a type of energy" cuts out most of physical existance (E = mc) which is either a remarkable scientific breakthrough or plain absurd.

Such statements have no place whatsoever in Misplaced Pages. --Damorbel (talk) 07:07, 27 May 2013 (UTC)

I have reversed an edit made by PAR in connection with this discussion. PAR explained his removal of my edit with the comment "heat is not a quantity, it is a process." This is a good example of the fundamental errors in the article - heat transfer is indeed a process, a very important engineering process but, as with many engineering terms, it is a handy short form for "transfer of heat energy". It would seem that this (lack of) distinction infects the whole article. --Damorbel (talk) 06:37, 28 May 2013 (UTC)

PAR is correct. Heat, like commercial electricity, can be discussed in either units of energy or power. But also like commercial electricity, heat is assumed to always flow. Unlike static electricity there is no static heat, and in any case, since there is certainly no static commercial electricity, it would be silly to imagine that the electric power company sells you a flow of commercial static electricity. Just because you get charged for electrical energy in joules (kw*hr) does not imply that the electrical energy ever arrived as anything else other than an energy FLOW. Heat is the the same. It is a type of energy that we always see in flow, and never rest. However, just as with commercial electricity, heat can be integrated and discussed in energy units. SBHarris 17:09, 28 May 2013 (UTC)

Sbharris, I would like to understand you more clearly. When you write:-

Heat, like commercial electricity, can be discussed in either units of energy or power.

Do you mean by this that the article should not distinguish between energy (joules) and power (watts, kWh, etc.)?

This is the distinction I am making and I do think any disagreement should be resolved quickly. --Damorbel (talk) 17:34, 28 May 2013 (UTC)

This article cannot make a big point of distinguishing kw from kw hrs. Commercial electrity is discussed in both terms and so is heat. But we cannot push the analogy too far because while charge is conserved, heat is not. Thus , the total heat absorbed by an object need not be its heat content. The very idea of heat content, due to nonconservation, is a bad idea. As well speak of an object's work content as its heat content. "Thermal energy content" sounds better but is no more legitimate. "Thermal energy flow" is as silly as static electricy flow. There is no static thermal energy. And we already have a name for thermal energy flow: it's called "heat." SBHarris 18:05, 28 May 2013 (UTC)

Another analogy - if you have a pond of water being fed by two streams, the "heat" stream and the "work" stream, the amount of water in the pond is not and cannot be divided up into "heat stream water" and "work stream water". Water is water. There is water added by the "heat stream" and there is water added by the "work stream", but once it's in the pond, it's just water. The amount of water in the pond is analogous to the internal energy. There is no heat energy, there is no work energy, there is only internal energy, and it is changed by the heat process or by the work process. PAR (talk) 07:45, 29 May 2013 (UTC)

Sorry, mass flow ("stream of water") is an invalid argument for either heat or work, neither of which are conserved as is energy.

The problem with the article is that it doesn't distinguish between heat energy (joules) and heat transfer (watts = joules/sec.), until it does it remains rubbish. --Damorbel (talk) 08:46, 29 May 2013 (UTC)

Joules / sec would be rate of energy transfer. That's not what we're talking about here. We're talking about the integral of that over time to give a total amount of energy transferred. Which would be measured in Joules. Or kilowatt-hours, just like your electricity meter does.

Of course, just because so many joules of electricity have come into your home, that doesn't mean that you can now say that your house now contains that many more joules of electrical energy. Because that wouldn't be meaningful. Similarly, in thermodynamics, heat is a measure of an amount of energy that has been transferred -- but not (at least, not in current usage) any identifiable aspect of the current state of the system itself. Jheald (talk) 09:59, 29 May 2013 (UTC)

Latest change to the article (Jheald )

Jheald has reversed my edit with the comment "WP has to reflect the position of the scientific community."

Since the article currently has:-

Heat is not a property of a system or body, but instead is always associated with a process of some kind, and is synonymous with heat flow and heat transfer.

- which is not compatible with the fact that the energy content of matter is directly proportional to its absolute temperature, i.e. its heat; whereas Heat transfer is proportional to temperature difference, not to absolute temperature. These are quite different matters and a Wiki article should make this quite clear. --Damorbel (talk) 05:38, 29 May 2013 (UTC)

As I wrote in my edit summary: WP has to reflect the position of the scientific community, not the personal theses of Damorbel.

I don't see any point in getting into prolonged further discussion with you about this. People have tried in the past, and it makes as much impression as talking to a brick wall. As Arbcom have reminded us in the past, talk pages are for improving articles, not for trying to straighten out your misunderstandings about physics.

So I'm not going to get into a discussion with you about this, and in future I shall just revert any more of this WP:OR from you on sight. Jheald (talk) 10:06, 29 May 2013 (UTC)

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