What is Enthalpy?
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- Опубліковано 7 вер 2024
- In this video, we define and discuss enthalpy, which is the sum of the internal energy and the product of the pressure and volume associated with a particular thermochemical process. Under constant pressure conditions, the change in enthalpy of a system is equivalent to the heat absorbed or released by that system.
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Hey everyone! 😃
If you're interested in more thermochemistry content, check out my thermochemistry playlist by clicking the link below 🔗👇
ua-cam.com/play/PLJ9LZQTiBOFElT2AQiegNrp-cwXaA0mlK.html
I gotta say, as an HVAC tech working in the field trying to get a better understanding of enthalpy, you saying pressure is generally constant and work doesn't matter made this almost irrelevant to the real world application. This seems like a way to calculate how much an uninsulated window heats a house. Very frustrating.
Ben, congrats, this is the most clear explanation about enthalpy I have even seen. I am a chemical engineer and people in my field just take for granted the word enthalpy but most of them do not understand the real concept (including me until today).
thanks for your work doing such educational videos
all the best from Germany
Thanks for your kind words! Much love from the USA! 😃
I spent a whole evening to find a clear definition. Finally, I got it. Thank you very much.
You're very welcome! Thanks so much for watching 😀
Only video I've come across that makes enthalpy make sense. Other videos just recite the formula! Thank you.
@@daphnec4016 so glad to hear that! Always good to know WHY!
Thank you for your kind words.
Its my first year in college and I LOVE YOUR VIDEOSSS i finally understand chemistry :)
Bruh I’m studying this in my end of middle school
Until today im still in college.. 😂😂😂😂😂
Have u graduated?
Where are u now
i have been just learning the formula without knowing the actual meaning of enthalpy. thank u very much for the explanation. love from India
You're very welcome 😀
There's thousands of videos that gives an intuition of entropy but this is the only that I found that gives, in the first minute, an idea of why is enthalpy useful. Thanks.
Thank YOU! That's really helpful feedback! 😀
This was sooooooo useful! You explain things in a very clear way and it all make sense ❤❤❤❤❤❤❤❤❤please don't stop posting okra
Really helpful do you have a video where you go more in detail? I’m suffering through physical chemistry right now and the integrals are killing me it’s super hard to find any physical chemistry stuff on youtube
You can check the TMP Chem channel, it's very very interesting ;)
Thank you so much. Your description was clear and it was very helpful for me.
You're very welcome!
My goodness this was life changing. Thank you!
You're very welcome 😀
Great Explanasion
Thanks! 😃
Good explanation!
The only thing that bugs me is the capital and lower case letters.
I learned that capitals are total values and lower case letters are "per mass".
Which means that the q and w should be capital or all the others lower case.
What is the meaning of Change in Enthalpy when the pressure is not constant? In some problems deltaH was given directly by n×cp×deltaT even when the process was adiabatic and pressure varied
Enthalpy is a state function, that doesn't depend on the path taken. You can heat the gas at constant pressure to give it its full change in enthalpy, and then take an isothermal process to the final condition. Isothermal processes with an ideal gas have no change in enthalpy. This will have exactly the same change in enthalpy, as if you take a process with varying pressure. The heat and work will be different, but the change in enthalpy will not.
The change in enthalpy is still useful for such a process. You see this parameter used, in turbines and compressors, where the process ideally is adiabatic. The rate of work done on the gas compressing it (or by the gas expanding it in a turbine) equals the mass flow rate times the change in enthalpy. Since it is an open system process, rather than a closed system process, we need to account for energy through enthalpy, rather than internal energy.
just wanna say I LOVE YOU! YOU'RE SO AWESOME and helpful with chemistry!!!
this was super useful! thanks!
You're very welcome! Thanks for watching 😀
Thank you sir, may Allah bless you
You're very welcome! Thanks for watching 😀
Thank you! Great explanation! Will help with my Climate Reality Presentation!
Wow, you summed it up in a very easy way!
Thanks! I'm glad it was helpful 😃
Nice video.. Thank you
so what does the steam table value gives us mean? Say at 300C and 5bar pressure, the enthalpy value of water/steam is 2534kJ/kg (NOT ACTUAL VALUE). So what is this value? Does it say if we raise the temperature of 1kg liquid at a constant pressure of 5 bar from 0C to 300C, we will need 2534kJ ??
I don't understand the question. Could you rephrase it?
The datum at which enthalpy is defined as zero, is arbitrary. You need to use steam tables with the same reference point. It's common to define it at zero at a point such as 0C and saturated liquid. Refrigeration tables define it at zero at -40C and saturated liquid.
It is only difference between enthalpy values in steam tables that means anything. And an application of this, is finding the power produced expanding the steam in a turbine.
Awesome content! This explained it so clearly, you're amazing at teaching!
Thanks, glad you enjoyed it! 😀
Very useful 😃
Awesome! Glad I could help 😀
Thank you. You made that so easy
You're very welcome! I'm glad I could help.
thanks, clear and useful explanation !
You're very welcome!
Many thanks for watching 😀
Thank you so so much!! I finally get it
Thank you!!!
You're very welcome! I'm glad it clicked for ya 😃
me reading your title for the first time was Benis
Lol nice
Thank you Ben.
Thanks✨
You're very welcome 😀
Here 9 years later using this vid to study for my AP chem test🫶 updating later what my score is
Best of luck!
@@BensChemVideosI PASSED RAHHHH TY BENSCHEMVIDEOS
it's not just useful,instead it's tooooooo useful
Thank you for your kind words, and thanks for watching! 😀
thank you
You're very welcome 😀
Thank you Sir
I love your videos, they're excellent!!
awesome man! thank you!
You're very welcome! Many thanks for watching 😀
Great video, thank you!
You're very welcome!
Thanks man. It was really helpful
You're very welcome! Many thanks for watching 😀
Why is change in enthalpy equal to q+w-w when w = -p delta V? Wouldn't it just be change in enthalpy is equal to q+w(-p delta V)?
@@daphnec4016 I think the video explains it better than I could in a comment, but I'll give it a shot.
DeltaH is equal to deltaE + P * deltaV
If deltaE is equal to q + w (first law), then delta H is equal to q + w + P*deltaV.
If w = -P*deltaV, then POSITIVE P*DeltaV is equal to -w
Substituting -w in place of the P*deltaV term in the enthalpy equation gives...
DeltaH = q + w - w
The w's cancel, and we're left with q.
@@BensChemVideos thank you!
@@daphnec4016 you bet!
Amazing explanation! Subscribed 😎
Many thanks! 😃
really helpful thanks.. my OCD ass tried to scratch that red dot away tho
You're very welcome! Many thanks for watching 😀
Wait so enthrall is basically heat released or absorbed under constant pressure???
Yes, enthalpy is basically the absorption or release of heat under conditions of constant pressure. Thanks for watching!
Ben's Chem Videos oh thank you so much 😊
@@jenniferwang946 You bet!
thanks so much man
You're very welcome! Thanks for watching 😀
I’m getting lost at the end. How did we get “w-w”?
Thanks a lot
You're very welcome! Thanks for watching 😀
Mr Ben I thought the symbol for Internal Energy was H. I see you are using E. Are we allowed to use E?
I've seen both "E" and "U" for internal energy. I've never seen "H" used to represent internal energy.
It doesn't matter too much what symbol you use, as long as you and those with whom you communicate all agree on terms.
@@BensChemVideos thank you, I think I was confusing it with enthalpy sorry : )
Thank you ❤️
You're very welcome! Thanks for watching!
@@BensChemVideos ❣️
Is work always negative even when the surrounding is the one that does work on the system??...
If the system is doing work on the surroundings, then work is negative.
If the surroundings are doing work on the system, then work is positive.
The sign convention is arbitrary, and depends on what standards you are using. I'm accustomed to the heat engine standard, where heat added to the system is positive, and work done by the system is positive.
To sum it up Enthalpy is the way to say it is the change in heat. Not exactly but yeah.
Enthalpy is the energy needed to create a substance (internal energy U), plus the energy needed to make space for the substance (P*V).
enthalpy ko energy khte h ky
If enthalpy is only defined for constant pressure then why do they talk about enthalpy in other processes and what does enthalpy mean in other processes
Enthalpy is a state function, that doesn't depend on the path taken. You can heat the gas at constant pressure to give it its full change in enthalpy, and then take an isothermal process to the final condition. Isothermal processes with an ideal gas have no change in enthalpy. This will have exactly the same change in enthalpy, as if you take a process with varying pressure. The heat and work will be different, but the change in enthalpy will not.
The change in enthalpy is still useful for such a process. You see this parameter used, in turbines and compressors, where the process ideally is adiabatic. The rate of work done on the gas compressing it (or by the gas expanding it in a turbine) equals the mass flow rate times the change in enthalpy. Since it is an open system process, rather than a closed system process, we need to account for energy through enthalpy, rather than internal energy.
Hi
High school AP bio freshman’s anyone ??? 😭
I still don't understand
I hope you understood after 7 years