What is heat?

[finiter]

What is heat?

 

(i). Potential energy

(ii). Kinetic energy

(iii). The state of an individual particle/wave

(iv). The state of an individual atom

(v). The state of a collection of particles/waves

(vi). The state of a collection of atoms, ie, a body

(vii). Something else

[Leader Bee]

Heat can be described as an increase in the movement of atoms contained within a substance.

 

The way you've posed the question sounds a bit Home work-ey and we can't just hand out answers.

Edited August 15, 2011 by Leader Bee

[swansont]

The way you've posed the question sounds a bit Home work-ey and we can't just hand out answers.

IMO if it's HW it's one of the poorer questions I've run across, since the answer would be vii) something else.

 

Heat is thermal energy being transferred. Depending on context it can refer to the process or the energy.

[finiter]

Heat can be described as an increase in the movement of atoms contained within a substance.

 

So can I come to the conclusion that a single atom or a system of subatomic particles cannot have heat energy.

 

IMO if it's HW it's one of the poorer questions I've run across, since the answer would be vii) something else.

 

Heat is thermal energy being transferred. Depending on context it can refer to the process or the energy.

 

How can we explain the term 'thermal energy"?

[michel123456]

Is this about heat or about temperature? (IIRC we've run through this before)

[Tom Booth]

I tend to go with the idea that "Heat" is just a word used to describe a subjective human experience.

 

The old experiment where one places ones right hand in a bowl of hot water and left in a bowl of cold water and then move them both into a bowl of lukewarm water. The one bowl of water then feels both "Hot" and "Cold" simultaneously.

 

According to the "Kinetic Theory of Gases" there is no such thing as "Heat" as such but rather a greater or lesser degree of motion or kinetic energy.

 

So when one hand feels hot and the other cold in the same bowl of water it is an accurate perception if thought of in terms of the transfer of kinetic energy.

 

In such a case the lukewarm water is transferring kinetic or "Heat" energy to the cold hand while also receiving kinetic energy from the "Hot" hand. The sensation of "Hot" or "Cold" then is a symptom of kinetic energy either entering or leaving a nerve ending as the case may be.

 

Heat from sunshine would then be the sensation of photons imparting some kinetic energy to some skin molecules.

 

It is possible to make atoms cold by having them collide with other atoms. Since heat is motion, if there is a direct hit or "head on collision" between two atoms they will cancel each others kinetic energy and their "temperature" will drop to near absolute zero.

 

Very energetic atoms tend to bump into one another and so stay spaced further apart (on average) or in other words "expand" which is the actual way heat is measured - mercury or some such expanding in a thermometer.

 

These are theories, as I understand. What are called atoms or molecules have sort of dissolved of late into "wavicles" - waves have become particles and particles waves so terms like "bumping into" or "Motion of particles" and so forth are only models to provide some sort of image to aid understanding, what is really going on - I haven't a clue really.

[finiter]

Is this about heat or about temperature? (IIRC we've run through this before)

I want to know what exactly is heat energy. Whether it is potential energy or kinetic energy, and whether a single particle/atom can have heat energy.

[swansont]

According to the "Kinetic Theory of Gases" there is no such thing as "Heat" as such but rather a greater or lesser degree of motion or kinetic energy.

No, not really. Kinetic theory is a subset of thermodynamics. Heat is not mentioned in the discussion because it is not within its scope, not because it proclaims that there is no such thing.

 

I want to know what exactly is heat energy. Whether it is potential energy or kinetic energy, and whether a single particle/atom can have heat energy.

No, a single particle cannot have heat. Heat is the net energy flow owing to a temperature difference.

[finiter]

No, not really. Kinetic theory is a subset of thermodynamics. Heat is not mentioned in the discussion because it is not within its scope, not because it proclaims that there is no such thing.

My notion about heat is the same (whether right or wrong)

 

No, a single particle cannot have heat. Heat is the net energy flow owing to a temperature difference.

An atom contains more than one particle. However, the electrons are bound and remain in the respective orbitals. So I think an atom also cannot have heat energy. So the question that I would like to ask is, "Can we restrict the concept of heat to 'systems containing atoms and molecules' only, ie, masses like Earth, sun, etc."

[questionposter]

Is heat caused by the fact that when particles absorb infrared light, they go into a higher energy level, so since the atoms have a larger radius now, they bump into each other more frequently and with more potential energy supporting the electro-magnetic repulsion between electrons? Although I don't get exactly how heat would be transferred in that scenario. For some reason, the electrons would have to go to their previous state in order to release the infrared light, so does that mean that infrared light is released because atoms bump into each other when an object is heated up?

Edited August 17, 2011 by questionposter

[swansont]

Is heat caused by the fact that when particles absorb infrared light, they go into a higher energy level, so since the atoms have a larger radius now, they bump into each other more frequently and with more potential energy supporting the electro-magnetic repulsion between electrons? Although I don't get exactly how heat would be transferred in that scenario. For some reason, the electrons would have to go to their previous state in order to release the infrared light, so does that mean that infrared light is released because atoms bump into each other when an object is heated up?

No.

 

Absorbing radiation (it doesn't have to be IR) does not make the atoms bigger. It does not have to make them jump an energy level — it can excite a vibrational or rotational mode in a molecule. The important thing is the atom has more kinetic energy. That's why the temperature goes up.

 

The heat in that scenario is the radiation.

 

An atom contains more than one particle. However, the electrons are bound and remain in the respective orbitals. So I think an atom also cannot have heat energy. So the question that I would like to ask is, "Can we restrict the concept of heat to 'systems containing atoms and molecules' only, ie, masses like Earth, sun, etc."

Heat can be in the form of radiation.

[Tom Booth]

No, not really. Kinetic theory is a subset of thermodynamics. Heat is not mentioned in the discussion because it is not within its scope, not because it proclaims that there is no such thing.

 

It "proclaims" as far as I understand it, that the ONLY energy a gas can have is HEAT but also states that this (so-called) "heat" is in the form of KINETIC energy or motion - thus creating in my mind an identity between "heat energy" and "kinetic energy".

 

"Heat" is a description of a sensation or an effect not the thing itself. If "heat" is transferred from particle "A" to particle "B" then particle A looses kinetic energy and B gains kinetic energy as a billiard ball imparts its motion to another when striking into it.

 

If the "ONLY" energy in a gas is kinetic energy then it would seem to me that "HEAT" is just a euphemism or substitute term for kinetic energy or relative motion.

 

At any rate, HEAT certainly IS mentioned in connection with "The kinetic theory of gases" and "heat" is absolutely well within the scope of the theory - in fact it is called, alternatively, "the kinetic theory of heat" is it not ?

 

----------------------

kinetic theory of heat

 

noun Physics .

a theory that the temperature of a body is determined by the average kinetic energy of its particles and that an inflow of heat increases this energy.

 

http://dictionary.reference.com/browse/kinetic+theory+of+heat

----------------------

kinetic theory of heat - a theory that the temperature of a body increases when kinetic energy increases

 

kinetic theory of gases - (physics) a theory that gases consist of small particles in random motion

 

http://www.thefreedictionary.com/kinetic+theory+of+heat

----------------------

 

To my mind, if so-called "heat" is ACTUALLY just the "average kinetic energy" of a group of particles then an entity - "HEAT" does not in actuality exist.

 

No, a single particle cannot have heat. Heat is the net energy flow owing to a temperature difference.

 

What is the "average kinetic energy" of a single particle?

 

If it were ZERO then a group of particles could not have heat either as

 

0+0 / 2 = 0

 

A single particle can have "kinetic energy" in relation to another particle assuming there is more than one particle in the universe and that these particles are in some kind of relative motion to one another.

 

So... heat is kinetic energy is potential energy

 

I say "potential energy" as there is no actual energy transfer unless there is some sort of collision.

 

So what is the "momentum" of a particle traveling in a vacuum?

 

There is no such thing as momentum either as motion is relative - if there were no other objects but the one carrying the "momentum" there would be no momentum. There is no such entity in actuality.

 

Infrared light is a photon in motion traveling somewhere.

 

Is there such a thing as a photon not traveling?

 

Is a "photon" a particle or a wave ?

 

Seems like whatever way you look at it everything eventually dissolves into nothingness or something rather undefinable.

 

Earlier I referred to Bose Einstein Condensate, though I forgot what it was called.

 

What happens to matter at absolute zero ?

 

Temperature and motion or kinetic energy are different terms for the same thing though I would say that kinetic energy is more of an actual something while "heat" is just a somewhat subjective and descriptive term of that something but not an actual thing in itself.

 

------------------

"When an object feels hot, the atoms inside it are moving fast in random directions, and when it feels cold, they are moving slowly. Our body interprets that random atomic motion into what we feel as hot and cold"

 

http://www.colorado.edu/physics/2000/bec/temperature.html

------------------

 

This last link is an excellent interactive presentation of BEC (Bose Einstein Condensate) and all about what heat is, what kinetic energy is temperature etc. Very informative and easy to understand and rather mind boggling at the same time in regard to the experimental proofs and demonstrations.

[pantheory]

What is heat?

 

(i). Potential energy

(ii). Kinetic energy

(iii). The state of an individual particle/wave

(iv). The state of an individual atom

(v). The state of a collection of particles/waves

(vi). The state of a collection of atoms, ie, a body

(vii). Something else

Like michel123456 pointed out, there may be semantics involved concerning heat vs. temperature. The related theory has been called the Kinetic Theory of Heat even though I believe that maybe temperature might be a better word for it. Like everything in physics, I believe, it is a simple concept. You apply heat to a source by radiation, conduction, or convection, and its molecular structure increases its oscillation. By these means heat can come from anywhere. Generally speaking everything has a temperature to it which is a symptom of its internal molecular oscillation, concerning a solid, liquid, gas, or plasma. This oscillation can produce waves of EM radiation emanating from its surface. When in the infra-red range we call such radiation heat, when in the visible range we call it light, and so on.

//

Edited August 17, 2011 by pantheory

[swansont]

It "proclaims" as far as I understand it, that the ONLY energy a gas can have is HEAT but also states that this (so-called) "heat" is in the form of KINETIC energy or motion - thus creating in my mind an identity between "heat energy" and "kinetic energy".

 

"Heat" is a description of a sensation or an effect not the thing itself. If "heat" is transferred from particle "A" to particle "B" then particle A looses kinetic energy and B gains kinetic energy as a billiard ball imparts its motion to another when striking into it.

 

If the "ONLY" energy in a gas is kinetic energy then it would seem to me that "HEAT" is just a euphemism or substitute term for kinetic energy or relative motion.

 

At any rate, HEAT certainly IS mentioned in connection with "The kinetic theory of gases" and "heat" is absolutely well within the scope of the theory - in fact it is called, alternatively, "the kinetic theory of heat" is it not ?

 

 

Depends on what you're referring to. The kinetic theory of gases and the theory of heat are not identical. The kinetic theory of gases does not come up with some definition of Q independent of thermodynamics. The kinetic theory of gases states that the only ENERGY and ideal gas has is kinetic, and that the average kinetic energy gives you the temperature. Temperature ≠ heat

 

So... heat is kinetic energy is potential energy

No, it is not.

 

When in the infra-red range we call such radiation heat, when in the visible range we call it light, and so on.

In common practice, yes, but that's wrong. Light from the sun is heat, even though much of it is in the visible range. The sun is approximately a blackbody, at about 6000K. It radiates energy as a result: that's heat. Most objects with which we are familiar, that are above ambient temperature, are not incandescent, so most of the radiant energy is in the infrared. That is likely what leads to the misconception that IR=heat.

[pantheory]

pantheory, on 17 August 2011 - 10:28 AM, said:

 

... when in the infra-red range we call such radiation heat, when in the visible range we call it light, and so on.

In common practice, yes, but that's wrong. Light from the sun is heat, even though much of it is in the visible range. The sun is approximately a blackbody, at about 6000K. It radiates energy as a result: that's heat. Most objects with which we are familiar, that are above ambient temperature, are not incandescent, so most of the radiant energy is in the infrared. That is likely what leads to the misconception that IR=heat.

Noted

..

Edited August 17, 2011 by pantheory

[Tom Booth]

Depends on what you're referring to. The kinetic theory of gases and the (kinetic) theory of heat are not identical.

 

Practically speaking, in this context, they amount to the same thing. "Heat" in a gas or otherwise is kinetic energy.

 

The kinetic theory of gases does not come up with some definition of Q independent of thermodynamics. The kinetic theory of gases states that the only ENERGY and ideal gas has is kinetic, and that the average kinetic energy gives you the temperature. Temperature ≠ heat

 

No, temperature does not EQUAL heat. Temperature is a measure of heat but you are just playing semantic games there.

 

The question is: "What IS heat?".

 

"IS" implies an existence or actuality. A measurement is not the thing measured.

 

"Heat" is not an IS (existent thing) either. Not a thing in itself.

 

--------------

"Microscopically, the thermal energy is the kinetic energy of a system's constituent particles"

 

http://en.wikipedia.org/wiki/Thermal_energy

--------------

 

You can talk about the kinetic theory of Gas, Heat, or Matter, they all amount to the same thing that heat or "thermal energy" is kinetic energy.

 

What distinguishes different states of matter, solid, liquid or gas is the relative motion of the particles.

 

I've never seen a "heat" object represented in a particle collision (bubble chamber) or in a feynman diagram. There is no "heat particle" or existent "thing" or object, particle, wave, solid, liquid or gaseous or any other substance or entity "HEAT".

 

You have degrees of relative motion of particles, fast, slow or whatever. There is, it seems to me, no such thing as "thermal energy" other than as a convenient manner of speaking in terms of subjective human experience or observed effects such as mercury rising in a thermometer. The reason the mercury rises, however, is due to a transfer of kinetic energy or molecular motion not any kind of actual "heat" entity.

 

If you want to know "What is heat?" there is no such thing. Its just a conceptual framework for describing in terms of human experience something not directly appreciable via human perception. We cannot see the motion of the particles but we can feel the subjective impression of that motion as so-called "Heat".

 

...Light from the sun is heat, even though much of it is in the visible range.

 

"Light from the sun is heat" ? "Visible range" ?

 

Visible range of what ? Heat ?

 

I don't think you have any idea what you're talking about.

 

Maybe I don't either but I'm not pretending to, at least I'm not making dogmatic assertions without foundation or supporting references.

 

Light, infrared, visible or invisible is not heat. People often associate heat with infrared light but light, infrared, "from the sun" or otherwise is not heat.

 

Heat might be called a property of light or maybe you could say that light carries heat/energy or something but to say light IS heat is like saying a soccer ball is a kick or a fist is a punch in the nose.

[finiter]

Heat can be in the form of radiation.

How can heat remain as radiation? There, of course, is a relation between the wavelength of the radiation emitted by a body and the temperature of the body. The radiation just tells the temperature of the body that remains in the background. Without that back ground, it tells us nothing other than that the energy quanta in it have certain amounts of energy. Can we say an x-ray is very hot? If you say it is hotter than infrared rays, then you have to agree with what Tom Booth says - that there is nothing like heat, it is just kinetic energy.

 

In common practice, yes, but that's wrong. That is likely what leads to the misconception that IR=heat.

You have corrected it. I posted the above before reading this

 

Like everything in physics, I believe, it is a simple concept.//

Simple, is it? That is what one would expect, at least about the fundamentals in physics. But, even the fundamental concepts like heat, force, etc. are not well defined. These words seem more philosophic than pertaining to science, their meanings depending upon the school of thought. If asked to define, one may just beat about the bush and ask, "now you got it?"

 

If you want to know "What is heat?" there is no such thing. Its just a conceptual framework for describing in terms of human experience something not directly appreciable via human perception. We cannot see the motion of the particles but we can feel the subjective impression of that motion as so-called "Heat".

You may or may not be correct. Suppose you have two containers, one larger than the other. Let each contain the same number of atoms of the same gas, and let their average kinetic energies be the same. In that situation, will the both have the same temperature?

[pantheory]

Simple, is it? That is what one would expect, at least about the fundamentals in physics. But, even the fundamental concepts like heat, force, etc. are not well defined.

I agree they are not well defined at present, but I believe the concepts and definitions are quite simple. In time I think present arguments professing complication of fundamental physics will disappear based upon future observations

 

These words seem more philosophic than pertaining to science, their meanings depending upon the school of thought.

You are correct. This is the present way of looking at simple explanations, as being philosophical or metaphysical. Since I think that reality is relatively simple, I believe this characterization is often wrong.

 

If asked to define, one may just beat about the bush and ask, "now you got it?"

One could. But if you believe you know a simple valid perspective/ definition, you could simply provide it

//

Edited August 18, 2011 by pantheory

[swansont]

Practically speaking, in this context, they amount to the same thing. "Heat" in a gas or otherwise is kinetic energy.

 

 

 

No, temperature does not EQUAL heat. Temperature is a measure of heat but you are just playing semantic games there.

 

Absolutely not. Heat is not kinetic energy, nor is temperature a measure of heat.

 

--------------

"Microscopically, the thermal energy is the kinetic energy of a system's constituent particles"

 

http://en.wikipedia.org/wiki/Thermal_energy

--------------

Thermal energy is not heat, either. From that link:

When two thermodynamic systems with different temperatures are brought into diathermic contact, they exchange energy in form of heat, which is a transfer of thermal energy from the system of higher temperature to the colder system.

 

Note it is not the thermal energy itself, contained in the system. It's the transfer.

 

Light, infrared, visible or invisible is not heat. People often associate heat with infrared light but light, infrared, "from the sun" or otherwise is not heat.

It most certainly is. Energy transfer from a temperature difference is heat.

 

How can heat remain as radiation? There, of course, is a relation between the wavelength of the radiation emitted by a body and the temperature of the body. The radiation just tells the temperature of the body that remains in the background. Without that back ground, it tells us nothing other than that the energy quanta in it have certain amounts of energy. Can we say an x-ray is very hot? If you say it is hotter than infrared rays, then you have to agree with what Tom Booth says - that there is nothing like heat, it is just kinetic energy.

I don't know what "heat remain as radiation" is supposed to mean.

 

"Hot" and "cold" are descriptions of temperature. Heat will not be hot, the object will be. So no, even if an x-ray was from a thermal source, it would not be hot. An x-ray from a non-thermal source would not be heat — heat transfer is from a temperature difference.

 

 

Unfortunately the terminology of basic thermodynamics is very sloppy because it's used in so many ways. That leads to a great deal of confusion.

[finiter]

Since I think that reality is relatively simple, I believe this characterization is often wrong.

Please explain a little bit.

 

One could. But if you believe you know a simple valid perspective/ definition, you could simply provide it .

//

I just pointed out 'the absence of a simple valid perspective/ definition'.

 

 

 

 

It's the transfer... Unfortunately the terminology of basic thermodynamics is very sloppy because it's used in so many ways. That leads to a great deal of confusion.

So you say heat is transfer or flow, not thermal energy. Now I got your point. In that case, the question I would have asked is "what is thermal energy?" Is it just kinetic energy or does it exist in any other form. I mean whether the atoms of gas have thermal energy in addition to the kinetic energy.

[Tom Booth]

 

Tom Booth, on 17 August 2011 - 07:07 PM, said:

If you want to know "What is heat?" there is no such thing. Its just a conceptual framework for describing in terms of human experience something not directly appreciable via human perception. We cannot see the motion of the particles but we can feel the subjective impression of that motion as so-called "Heat".

 

You may or may not be correct. Suppose you have two containers, one larger than the other. Let each contain the same number of atoms of the same gas, and let their average kinetic energies be the same. In that situation, will the both have the same temperature?

 

Well for one thing, the scenario you describe is impossible. In such a situation, the "average kinetic energy" in relation to volume at least could not be the same.

 

If it were possible to put ones hand into each container, one would feel warmer than the other as in the large container the atoms would be spread out more and would "bump into" your hand less frequently.

 

But no, they would not have the same temperature but also the kinetic energy could not be "the same" either.

 

If you put a thermometer into each container, one thermometer, due to being bumped into by more atoms because they are squeezed closer together in a smaller container would have more energy transferred to it and so the mercury molecules in the thermometer would expand more.

 

In the larger container, due to the atoms being more spread out, the thermometer would be bumped into less often and so would read a lower temperature.

 

Each individual atom might have "the same" kinetic energy in terms of speed of travel but the "average" kinetic energy as measured by lets say square inch of volume of gas would not be the same.

 

There would be fewer atoms per whatever volume of gas in the larger container therefore the "average kinetic energy" for each unit of space could not be "the same" for both containers. Unless...

 

If you applied more "Heat" to the larger container.

 

That is, if you put the larger container on a stove and heated it up then the gas molecules or "atoms" would move faster.

 

But this does not make "Heat" a "Thing".

 

The molecules in the stove element are just moving faster and imparting their kinetic energy to the larger container whose molecules move faster so as the gas bumps into the sides of the container more kinetic energy is transferred to the gas inside the container. Then due to the gas in the larger container being more energetic the temperature and the "average kinetic energy" could be the same but it is arguable if a specific gas at different energy levels is "the same gas".

[spin-1/2-nuclei]

Suppose you have two containers, one larger than the other. Let each contain the same number of atoms of the same gas, and let their average kinetic energies be the same. In that situation, will the both have the same temperature?

 

Hello,

 

The poster whom you addressed this question to is correct.

 

If the average kinetic energies of the gasses are the same then their temperatures will be the same. The real question you should be asking here is what impact will container size have on the pressure and what effect will that have on the kinetic energy of the gasses?

 

From the kinetic theory of gases: gasses are made up of molecules where the system energy has surpassed the energy of the intermolecular attractive forces. Molecules in the gas phase are constantly moving (i.e. they have kinetic energy). This movement results in collisions with other gas molecules and in the case of a gas inside a container the walls of the container as well.

 

The relevant physical properties are mass, momentum, and energy.. noting that kinetic energy increases as both temperature and mass increase.

The momentum of an individual gas molecule = mass (times) velocity. The kinetic energy is 1/2mass (times) the square of the velocity.

 

When the gasses collide with the container a force perpendicular to the wall is exerted. Pressure is equal to the sum of the forces striking the container wall divided by the area of the wall. So the pressure of a gas is thus a measure of the average linear momentum of the moving gas molecules.

 

Thus, if you increase the pressure of your container (by reducing it's size but keeping the number of gas molecules constant as well as their kinetic energy) you will increase the temperature, which will in turn increase the kinetic energy - therefore they cannot be the same. Volume will increase in a container whose pressure has increased assuming that the walls of said container are flexible. If they aren't and you change the volume of the system it will either explode or implode depending on the circumstances.

 

getting back to the question of "what is heat?":

 

Heat is a measurement of energy. The hotter an object is, the faster the motion of the molecules in that object. Therefore "heat" is the TOTAL energy of all of the molecular motions in your system.

 

Temperature describes the average heat or thermal energy. Thermal energy can be transferred by conduction (transfer of energy from one molecule to another), convection (movement of heat by a liquid or a gas), or radiation (transfer of heat by electromagnetic waves).

 

Thus "heat" is the transfer or flow of energy from one object to another. Or rather, one area of higher energy to one area of lower energy. So, in this very literal definition of heat, one can say that a single particle (if and only if it existed in isolation in the vacuum) cannot posses "heat", THAT DOES NOT MEAN THAT IT CANNOT POSSESS KINETIC ENERGY. To suggest that there is no correlation between kinetic energy and heat is a descent into ridiculousness that will result in a significant waste of the time you spend studying these concepts.

 

The argument between the terms heat and temperature (while valid on a purely theoretical level) is really only saying that, because there would be nothing there to "observe" the heat - i.e. - the heat would not have anything to transfer to it would not exist. This in my opinion, while a useful academic point, is irrelevant when beginners are looking at the real world definitions of heat and what produces "heat" in molecules and other every day objects.

 

So, unless we want to needlessly create paradoxical situations by descending into the metaphysical arguments of Schrodinger's cat and the like, it is perfectly reasonable to say that kinetic energy is a result of molecular motion which increases the temperature which in turn increases the "hotness" of the object which is in fact observable in the form of heat and heat is in fact just a measure of the energy (that makes things hot) being transfered from one system to another.

 

A good way to prove this to yourself is to ask someone to try to explain the concept of heat to you without mentioning anything about temperature or molecular motion/kinetic energy.

 

Hope this was helpful,

Cheers

 

.That is, if you put the larger container on a stove and heated it up then the gas molecules or "atoms" would move faster.

 

But this does not make "Heat" a "Thing".

 

This is correct. Heat is not really a thing - it is a measure of a thing - and that thing is energy.

 

The molecules in the stove element are just moving faster and imparting their kinetic energy to the larger container whose molecules move faster so as the gas bumps into the sides of the container more kinetic energy is transferred to the gas inside the container. Then due to the gas in the larger container being more energetic the temperature and the "average kinetic energy" could be the same but it is arguable if a specific gas at different energy levels is "the same gas".

 

You're on the right track here, but just a few pointers, if you don't mind.

 

The kinetic energy of the gas molecules increasing or decreasing as a result of the external environment will not make the gasses into different gases. A chemical reaction has to take place in order to break bonds, and you must break chemical bonds in covalently bound structures to obtain a different substance. An increase in kinetic energy won't move the molecule into another energy level (as in it won't convert the electronic configurations of the molecule's atoms into other atoms), but rather it increases the molecular motions. So collisions, bond rotations, etc will be faster. Kinetic energy has a direct effect on the physical properties of molecules though.

 

An example of this is,

Water in the solid form (ice) has different kinetic energy than water in the liquid form. This is because in the liquid form water molecules can more easily move across each other. This is because they have more kinetic energy, and while they are still water molecules in the gas phase, they have even more kinetic energy resulting in the phase change.

 

Hopefully this was helpful,

Cheers

Edited August 18, 2011 by spin-1/2-nuclei

[Tom Booth]

Tom Booth, on 17 August 2011 - 07:07 PM, said:

--------------

"Microscopically, the thermal energy is the kinetic energy of a system's constituent particles"

 

http://en.wikipedia..../Thermal_energy

--------------

 

Thermal energy is not heat, either. From that link:

When two thermodynamic systems with different temperatures are brought into diathermic contact, they exchange energy in form of heat, which is a transfer of thermal energy from the system of higher temperature to the colder system.

 

Note it is not the thermal energy itself, contained in the system. It's the transfer.

 

I still say you are just getting tied up by the semantics.

 

#1."they exchange energy in form of heat"

 

which is:

 

#2 "a transfer of thermal energy"

 

These two statements are stated to be equivalent

 

Statement #1 "which is" Statement #2

 

exchange = transfer

 

thermal energy = heat

 

Putting it back together: "they exchange energy in form of heat, which is a transfer of thermal energy"

 

or:

 

""Microscopically, the thermal energy (= heat) is the kinetic energy of a system's constituent particles"

 

"Heat is Kinetic Energy"

http://www.vias.org/physics/bk2_03_02.html

 

"Thermal energy (heat) is kinetic energy"

http://mineral.gly.bris.ac.uk/geochemistry/pdflectures/Thermodynamics1.pdf

 

"Heat (or thermal) energy is kinetic energy due to motion of atoms and molecules."

http://okfirst.mesonet.org/train/meteorology/HeatTransfer.html

 

Stating or pointing out "It's the transfer" does not negate the fact that heat or thermal energy is kinetic energy.

 

The word "transfer" itself implies motion or kinetic energy. So sure, yeah, it is "the transfer"

 

A transfer of kinetic energy to my skin is interpreted by my nervous system as "heat" but there is no actual "heat particle" or "Heat" as such - as a thing in itself - being transferred. There is no such thing.

 

You cannot separate "Heat" and put it in a bottle.

[spin-1/2-nuclei]

You cannot separate "Heat" and put it in a bottle.

 

For what it's worth you are right, both academically and in normal everyday real world situations. The moment someone explains "heat" without mentioning kinetic energy or molecular motion, they will have won a Nobel prize, because it will change the way we view thermodynamics. You cannot separate the concept of heat from the concept of molecular motion and kinetic energy.

 

As I said in an earlier post:

 

Heat is the transfer of energy from one object to another. Temperature describes the average heat or thermal energy (you've also said this). Thermal energy can be transferred by conduction (transfer of energy from one molecule to another), convection (movement of heat by a liquid or a gas), or radiation (transfer of heat by electromagnetic waves)

 

Thus in the land of endless arguing for the sake of arguing - where people wonder if Schrodinger's cat is really dead/alive inside that box - perhaps he is just sleeping? - and whether or not the world around them is in fact filled with other autonomous humans - (could all be a figment of their imaginations?)...

 

the forest is lost through the trees, since to most people trying to understand this (who aren't going forth to get PhD's in particle physics and even most situations for people like me getting PhDs) a literal definition of heat is virtually useless..

 

As I said before, one can say that a single particle (if and only if it existed in isolation in the vacuum) cannot posses "heat", THAT DOES NOT MEAN THAT IT CANNOT POSSESS KINETIC ENERGY.

 

I'm really impressed with how much you've taught yourself.

Best of luck with the rest of your studies (be they at uni or for your own amusement).

Cheers

Edited August 18, 2011 by spin-1/2-nuclei

[pantheory]

You cannot separate "Heat" and put it in a bottle.

You can't, how shocking. You mean you propose to discard phlogiston theory?

 

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Edited August 18, 2011 by pantheory