Enthalpy Puns

Learned this a while ago dimaag udd gya, thought it might help some of y'all, I'm assuming you know basic thermo.

H = U + PV

so imagine you are a lazy physicist and tumhe jaanna hai ki hydrogen ko burn karne pe kitni energy milegi, and as you are lazy instead of doing the experiment, tum bas dekh lete ho ki neeche waale equation ki bond breaking aur bond formation ke baad net energy kitni mil rahi hai.

H2 + O2 ==> H2O

Fir after a while you decide to test your calculations, so what you do is maidaan me jaate ho aur hydrogen ko calculated activation heat provide karte ho, what you find is ki jitni extra energy tumhe mili after combustion is less than what you predicted. Why does this happen?

because jab tum hydrogen ko heat karte ho it expands and does work against the atmospheric pressure and steals some of the release heat you calculated to achieve this expansion. Ab boht inconvenient cheez hai but bohot common hai, most chem reactions take place at constant pressure so expansion ya contraction ki wajeh se energy ka ghapla hote rehta hai. so instead of always accounting for that extra atmospheric work in internal energy, we define a new term enthalpy

idhar jo PV part hai it his the work done to 'make space' for the process.

Mathematical proof for skeptic bastard --> (assuming expansion hora and constant pressure (why? because most chem reactions take place at const. pressure so we defined it that way))

ΔH = ΔU +PΔV

ΔU = ΔQ -PΔV + W⁰ (minus sign because expand krra, system is doing work on surrounding so
energy bahar jaari, W⁰ is other work like bond breaking electricy pass kiya etc)

ΔH = ΔQ + W⁰ this is the actual energy change including atmospheric work ka ghapla

New new seekha yeh, agar kuch galat lagey toh bataana.

I think it's D, but I'm not so sure.

https://preview.redd.it/t104ykj813c81.png?width=2880&format=png&auto=webp&s=18634ecdc78c87f9793e4ff934dc3ac3f2819fba

continuous combustion

continue to inject fuel and oxidizer into the working fluid over the length of the channel so that it is maintained constantly at the maximum pressure and temperature point

and like the larger a fraction of the cycle that continuous combustion maintains constant pressure, temperature, and volume conditions the higher the efficiency and enthalpy extraction will be

it's all the energy it takes to get up to a good working plasma that you ultimately can't extract right

but you can use the remaining energy in the working fluid after you have extracted everything you can to avoid paying that energy cost for additional mass

and you can go further and maintain the maximum enthalpy extration operating point

the two factors yield significant incremental enthalpy extraction and conversion efficiency for incremental mass relative to injecting the mass somewhere you have to give it most of that energy in the process of reacting it

like as the mass density of the slug of working fluid increases the temperature difference of the fluid due to mixing becomes insignificant and the injected mass just thermalizes right to optimal conditions before it encounters a friend and then when it finds a friend it leaves with significantly more velocity because it doesn't have to pay for ionization or thousands of degrees of thermal energy and the amount of kinetic energy is ^2 with velocity and you can extract a larger total delta v before it becomes non-MHD mass

also like this should be obvious and i don't know why it is not to MHD research people but the combustion event itself is a highly energetic process that involves the creation of moving charged particles

you do not want to do the MHD thing after the burny thing you want to do the burny thing in the MHD thing

I am not even sure I am going to need to bother with a steam turbine, I think there are probably enough options for incremental advancements in direct conversion to electric power via plasma electrochemistry and magnetohydrodynamics to get like 40-60% total heat extraction as productive electrical work without a turbomechanical stage, if not more.

also basically like every kind of molecular hydrogen chemistry has the potential to be retardedly energy dense in ways I think we don't really have a good reference for and it's important I think to appreciate that this doesn't just mean the energy storage density but also the power density potential, like basically the sustained thermal power of

I have my thermo two exam coming up and I'm really confused about this one concept. I have attached a screenshot of the question that made me realize I didn't quite understand and I just want to know if it's valid to use h in this case or if you have to use m(Cp)(delta T). If I do, could you please explain why? Thank you guys so much!! :)

https://preview.redd.it/yb2fxqyrf5481.png?width=786&format=png&auto=webp&s=168d7b0540816dbeb24780f84926b6ac9df8f767

Hey everyone

I am desperately looking for values of the Bond Dissociation Energies (or enthalpies or basically just the energy value of the bond) of the CH3CO–NHCH3, the CH3CO–OCH3, and CH3CO–SCH3 bond (I am referring to the Bond between carbon and either oxygen, sulfur, or nitrogen)I can't find values for the Ester versions (and also I don't want to use a Wikipedia page or anything „unprofessional“)Maybe someone knows a good publication where they have all those values?

Also I am not looking for the values for normal C-S, C-O and C-N bond. Its important that its the esters

I would very much appreciate any help!

I am currently writing a chem paper on arenes and bond strength of varying structures. I can't find any data online for bond dissociation enthalpy but I've found a bunch for IE, would I be able to link my findings with IE, to explain a trend for bond strength?

Saran Singh Sound Aim: To determine the enthalpy change of displacement between zinc powder and copper sulphate Zn (s) + CuSO4 (aq) Cu (s) + ZnSO4 (aq) Chemicals – CuSO­­­4 Solution ( concen.

As above.

I just started the course Thermodynamics and I can't really grasp the true definition of enthalpy. I don't want it explained via formula, I just want an example maybe and a clear definition of some sort.

Hello, I was studying for a test I have next week, and I found a solution online to a question that was asked on the previous semester's exam, but I am having trouble understanding the procedure done on the step b) of the solution (the rest are fine), could someone give me some insight?

On step b) the only value I was able to get was h1 only because it is calculated earlier when the temperature is 25 °C and the liquid is saturated. But from h2 to h8 I have no clue of how they are calculated, neither I understand why is h6 used for the quality at the output. I tried using the values given in the table between the mentioned pressures and temperatures but I couldn't get the same numbers. Any clue on what i'm doing wrong / what should I be doing?

I made a doc where I pasted the question and the online solution I found, also the Thermodynamics table used for the substance.

Sorry if my redaction is a bit poor, english is not my first language. Thanks a lot in advance!

DOC: https://docs.google.com/document/d/1XTSCY3B3xR-kmXo4cRyNgqeFt2Qj2RLwOcZc0lqbPF0/edit?usp=sharing

(Re-posted as my previous title triggered the auto-remove)

Hi, I’m currently a Junior in High School taking AP Chemistry. We went over enthalpy in class, but the teacher would not elaborate on what it actually was further than the equation (H = E + PV, H = q when P is constant). Out of both curiosity and a desire for better conceptual understanding, I’d appreciate an explanation of what enthalpy is, in essence, beyond just an equation. Thanks!

For starters I want to say I’m bad at this. I am most likely missing fundamentals and reaching for things that are way above my level. But don’t hold back. You may mention terms unfamiliar but useful for me to look into. I’ve assumed for a while that systems always tend towards their lowest energy states, for the purpose of order. But the second law of thermodynamics has proven me as wrong as I could be. Nature tends towards disorder. Systems “want” to get rid of energy but don’t want to be ordered. I assumed increasing enthalpy always increases entropy. And couldn’t figure out why there are spontaneous endothermic reactions in nature. I suppose endothermic processes are what’s confusing me most. Apart from phase changes.

Im doing my chemistry IA on 1-butanol, 2-butanol and 2-methyl 2-propanol having different enthalpies of combustion. but I still don't fully understand why that is, any help would be appreciated.

It's cold…

I've been still for

Far too long and

I just don't have

The same vibration.

 

There's too much pressure

And not enough volume.

I just don't have

The internal energy to

Displace my environment.

 

So motionless I stay.

Too focused on lost potential,

To see my potential loss.

 

Previous feedback:

https://www.reddit.com/r/OCPoetry/comments/pvriah/the_search_for_self/heciq61

https://www.reddit.com/r/OCPoetry/comments/pp5wmm/you_are_my_friend_possible_tw/hdlqs9s

Hello, first post here. I have been a deist for many years, even before I knew what the word meant. I am happy to be in good company.

My upbringing has been Protestant Christian, in the Methodist denomination; so I, in this mortal vessel, base most of my observations off of the teachings found therein. In my journey with deism I have come to discover that the forces that make up Enthalpy, taking things from lower order and creating higher order (like an acorn growing into a mighty oak), seem to be the forces that are most similar to what could be considered “godly”.

Many religions consider humanity to be made in the image of their God, or related to their God in some way: since we are walking & talking examples of high level enthalpy this checks out. Many religions give their Gods the role of creator of the universe: since forces of enthalpy allowed the stars and planets to form, and then for the gases to be trapped within the atmosphere, thusly creating the mostly closed system we live in here on Earth, this box is checked as well. Finally, humans in many cultures are said to behave in similar ways to their gods: whenever humans take raw materials and process them into something more useful we are acting in accordance with the forces of Enthalpy.

Enthalpy has a great interplay with deism as well, due to the fact that forces cannot be personal. Though they can still be prayed too and invoked. Doubtless times humanity has been its most remarkable and powerful while invoking the forces of Enthalpy; the Pyramids, the US constitution, the Mongolian horde, the Magna Carta, the Roman infrastructure, the internet, printing press, and many more.

In a closing statement, anyone who has taken a basic physics class knows that on the other side of Enthalpy are the forces of Entropy, and that those forces are more powerful as in the long-run everything will be reduced to quarks. These forces in my observation are why life should be regarded as extremely precious, as it is a direct opposition to the greater forces of the universe. Our role as a species should be to create higher order (which does not mean control) and help Enthalpy become the dominant force over Entropy.

All Glory to Enthalpy, my Lord God.

P.S. The Christian concept of “progress” is the closest theist belief to Enthalpy, and it has served the Christian people very well.