Adiabatic Flame Temperature

The enthalpy of combusion can be used to estimate the temperature at which a flame will burn.

[@YonePepe]

Wow! that is the coolest way I have ever seen to watch a class, with the floating "invisible" board. I'm almost graduating in mechanical engineering and my final paper will be about a comparison between the fundamental combustion parameters of hydrogen, natural gas, and ethanol. I was currently re-studying one of these parameters, the adiabatic flame temperature, and could not be more satisfied with this class! Thank you

[@PhysicalChemistry]

You're quite welcome. I'm glad you liked the video. Good luck with your paper

[@mortezakhoshbin]

Thank to you at 5:50 i again got the answer of one of my mind questions confusing me all the times. Thanks alot professor ❤️

[@PhysicalChemistry]

I'm glad to hear it. It's great to have a curious mind. And even better when your curiosity can be satisfied.

[@shaahinfazeli9095]

Thank you, Thank you, Thank you!

[@PhysicalChemistry]

My pleasure!

[@RajanyaMajumdarBiswas]

King come back

[@anoptainium]

A teacher can make or break a student . Thank you for all your help , Sir.

[@PhysicalChemistry]

And having good students makes all the difference to a teacher, as well. Thanks for taking the time to comment

[@Morpheus-zw4px]

great video, very good help. keep up the good work

[@shout404]

Hi!! I love love love your videos they have been super helpful for both my pchem course last semester and quantum chem course this semester. I was wondering if you could do some videos on molecular orbital theory? Thank you!! (:

[@PhysicalChemistry]

I'm glad they have been helpful. Thanks for the comment. MO theory is a good suggestion. I will definitely consider adding some more videos on that and related topics when I add more to the quantum section of the course.

[@shashidharsahu8272]

Thanks a lot for ur outstanding explanation sir . Love from India .plz complete physical spectroscopy ,humble request to you sir

[@PhysicalChemistry]

You're welcome, and thanks to you. I'm afraid you'll have to find someone else for videos on spectroscopy, though.

[@TriPharma]

Triple integral of electron position in a hydrogen atom , that's physical chemistry!

[@RichardKCollins]

I would pre-heat the oxygen and fuel molecules electromagnetically. Then record the 3D volumetric temperature distribution, tracking flow of reactants. To start. And find the temperature dependent heat capacities data or models. To start. Calibrate and optimized the linked models. Track spectroscopic IR, VIS, thermal, UV, whatever is available. Share the results. Richard Collins, The Internet Foundation

[@鏡輝-p1n]

Thank you for nice video! Btw, do we need to consider evaporation enthalpy of water as well?

[@yushinakaoka1294]

how did you learn how to write backwards??

[@PhysicalChemistry]

I didn't. Instead, the computer learned how to film backwards: kzbin.info/www/bejne/j57Ze4mhrq-VgsU

[@yakeenianpratapveerendrapr9239]

Sir please descibe maxwell equation of tharmodynamics derivation Your vedios are so helpful for me thank you sir

[@PhysicalChemistry]

See the video titled "Maxwell Relations": kzbin.info/www/bejne/qZjIdoVohtiLldE

[@LonelyBoy-tk8rs]

Very helpful thanks 😊

[@PhysicalChemistry]

You're welcome, glad to hear that

[@RajanyaMajumdarBiswas]

@@PhysicalChemistry Where are you my g?

[@ragibshahriar187]

I watched all your videos from 'Thermodynamic State' playlist. Have to say, these are so good! Thanks for clearing things and making the contents self contained.

[@PhysicalChemistry]

Great, I'm glad you found the playlist

[@AbdulHannan-uv6ym]

Is the specific heat capacity (Cp) commutative ? i.e. is this statement true Cp (H2O+N2+O2+CO2) = Cp(H2O) + Cp(O2) + Cp(N2) + Cp(CO2)

[@PhysicalChemistry]

Short answer: no Extensive (not commutative) is the word you're looking for. But either way, it is often not the case that the heat capacity of a mixture would be the same as the sum of the heat capacities of the pure individual components. However, for the case of gases, like we're talking about in this video, then it's not a bad approximation to assume that the heat capacity of the mixture is the sum of the individual component heat capacities. That's because in a gas the molecules are usually far away from each other, and don't affect each other very much.

[@siddharthaarava4661]

nice one

[@PhysicalChemistry]

Thanks

[@NN-yw5sp]

Not all heroes wear capes ❤️

[@trinitiscruggs1563]

Can you do electrochemistry from a physical chemistry standpoint?

[@PhysicalChemistry]

Thanks for the suggestion. That is definitely a topic that belongs in a thorough physical chemistry course. I haven't made videos on it yet, but will add it to my list.

[@ismaelarevalo4762]

Hello, good video. I have a question. Why are only the Cp of the products taken into account?

[@leonardosaurwein2110]

Great video!

[@pGgizle]

1) Shouldn’t the evaporation enthalpy of water be considered in the equation? 2) I believe that an iterative approach would be more accurate instead of considering average CP

[@PhysicalChemistry]

1) The heat of combustion specifies conversion of the hydrogen to H₂O(g), not H₂O(l). You can think of the heat of combustion as already factoring in the heat of vaporization, if you like. 2) You are definitely correct. The heat capacity Cₚ depends on T in a pretty complicated way (kzbin.info/www/bejne/fZicep-NbJuleqc), so just using an average Cₚ isn't very accurate. If you have better Cₚ(T) data, it is certainly better to use a numerical approach - such as iteratively evaluating the integral mentioned @18:48

[@pGgizle]

@@PhysicalChemistry Thank You for clarifying it!

[@alvinbratz2423]

Loved taking your class! One of my favorite courses at Clemson!

[@PhysicalChemistry]

Hi, Alvin! Your year was one of my favorite classes, too. I think you're the first one of my actual students to leave a comment, so thanks!

[@NN-yw5sp]

Thank you so much professor, very helpful!!😊

[@PhysicalChemistry]

Glad to be of service

[@liambuchan4162]

Can I ask if you cover the Electronic Properties of Solids (Free Electron Theory of Metals, Crystal Orbital Theory, Inorganic Semiconductors (p type, n type, p-n junctions) and Organic Semiconductors (graphene and carbon nanotubes, thiophene, quantum dots etc.)?

[@PhysicalChemistry]

No, sorry, those are not covered in any of my videos. They are definitely topics of interest to physical chemists, but typically not taught in the physical chemistry course (for chemists) that these videos cover.

[@liambuchan4162]

@@PhysicalChemistry I see, thank you. Can I also ask if you cover Statistical Thermodynamics or Time Dependent Quantum Mechanics?

[@PhysicalChemistry]

@@liambuchan4162 Time-dependent quantum mechanics: no. Statistical thermodynamics: most definitely yes. The course is organized around using statistical mechanics to explain thermodynamic concepts

[@liambuchan4162]

@@PhysicalChemistry Thanks!

[@mattm12124]

great video, whered you get the average heat capacities though? ive been looking around and cant find them. its odd to me that we're finding the end temperature, but need a value (the Cp) that we cant get without assuming an end temperature

[@PhysicalChemistry]

You're right, I had to have a rough guess of the final T in order to calculate the average. I got the C_P(T) values from the NIST web data (a great resource). It's true that average C_P will depend on the final T, but the final T also depends on the C_P values. It would be more accurate to solve the problem self-consistently, but that would have been complicated enough to obscure the main point of this video, so I took a more approximate approach

[@mattm12124]

@@PhysicalChemistry gotcha, yeah this seems to be a standard approach, dont mean to criticize. ill check the NIST stuff. just wanted values i could feel confident using for graded assignments. thanks for the reply

[@PhysicalChemistry]

@@mattm12124 webbook.nist.gov/chemistry/form-ser/

[@komma3366]

I just passed my last PChem class thanks to your videos. Great work!

[@PhysicalChemistry]

I'm happy to hear it

[@liambuchan4162]

Please can I ask if you will do electrochemistry (electrochemical cells, half cell reactions, Nernst equation etc)?

[@PhysicalChemistry]

Probably not. Those topics are often not covered in physical chemistry courses, because they are treated well in general chemistry and/or analytical chemistry. There is very little I would include in a PChem treatment that wouldn't just duplicate what is found in those textbooks or courses.

[@liambuchan4162]

@@PhysicalChemistry I see. Please can I ask what textbooks and exercises you recommend for electrochemistry? I find the Thermodynamics (such as the Eyring-Polanyi and Butler Volmer equations) and Kinetics (such as mass transport limiting current and the Cottrell equation) very difficult to understand and apply to questions. I the have Atkins' 11th Edition textbook.

[@PhysicalChemistry]

@@liambuchan4162 Ah, I see. Those are indeed more advanced than just general chemistry. The Eyring equation is not particular to electrochemistry, and is a great PChem topic. I'll add that to my list of things to cover in the kinetics section. Butler-Volmer is definitely electrochem, though, and not PChem. I don't have a great book recommendation for aqueous ionic chemistry / electrochemistry, unfortunately.

[@werner9643]

i have a question. is it possible to get a fuel to burn adiabatically in real life conditions? if for instance i burn gasoline(its adiabatic flame temperature with air as oxidizer is 2100 celsius degrees), how much lower will its flame temperature be in real conditions?

[@PhysicalChemistry]

Your suspicions are correct: adiabatic conditions are impossible to achieve for a flame. Since a flame needs an oxygen source, it is impossible to insulate it from the surroundings. So a significant amount of heat will be lost to the environment (indeed, this is often the whole point of burning the fuel!) and the process won't be adiabatic. Adiabaticity is a sort of "ideal" flame condition that we can't quite achieve. Think of it like the ideal gas law: no gases is ever truly ideal. Under some conditions it can be quite close, and under other conditions its a terrible approximation. But the ideal gas law still gives useful predictions. Likewise, no flame is ever truly adiabatic. The adiabatic flame temperature might give a reasonable estimate of the flame temperature if you burn in a carefully controlled stoichiometric ratio of fuel and oxygen, and pay a lot of attention to the flame conditions. Or it may be far from adiabatic in more normal situations. A real-world flame will probably be several hundred degrees below the adiabatic flame temperature at its hottest -- and will vary by many hundreds of degrees in different positions in the flame itself.

[@werner9643]

@@PhysicalChemistry thanks!!

[@Snubstatue4995]

very useful thank you

[@PhysicalChemistry]

You're quite welcome