"Let me do this in a different color" = Sal's catchphrase.

@rozito2086

5 жыл бұрын

There should be a compilation of sal saying it

@lusandasithole5704

3 жыл бұрын

Another one: " let me use a Magenta colour!" I love it when he says that. 😆

@Shadow12aven

3 жыл бұрын

Khan "Half of the video is me changing colours" Academy. lol.

"It's almost kinda too obvious for me to explain" Oh Sal. You overestimate me 🥲

@a-levelking8610

2 жыл бұрын

KZread asked me to give feedback about your comment lol

40 pages of textbook and five hours of lectures can't make me understand enthalpy, Khan did it in just 15 mins.

@whogavehimafork

5 жыл бұрын

Yep, my thermo book tends to not explain concepts very well, rather it focuses almost entirely on the mathematics.

@sirchomsky784

Жыл бұрын

Tag me

@virupannamedikinal

Жыл бұрын

Include me

@bigdogben

5 ай бұрын

Those books were probably explaining other stuff around enthalpy assuming you already knew what enthalpy is.

You have no idea how much appreciation I have for your videos. I'm practically self-teaching myself by watching your videos and I swear, I'm learning more than I'm lectured in class.

@debashreekonwar061

2 жыл бұрын

Truth

i would appreciate it if you could lend me your head for a day for my exams, will return to you ASAP. thanks

12 years later and you're videos are teaching us better than anything !

"if I'm sitting at the beach and I have my chemistry set" lol

@rubendragan6514

4 жыл бұрын

13:35

@addy7464

3 жыл бұрын

Thats too nerdy even for a nerd like me

Sal takes his chemistry set to the beach. What a nerd

Thank you for helping me not fail chemistry. Much love. -Julianne

He may sound funny, but he can explain things in such clear and simple manner only because he understood the subject very well and not just text book learning. When you think he teaches almost every subject with such mastery, he is AMAZING..!!

"So I´m sitting at the beach and I have my chemistry set". A perfectly reasonable scenario haha. Love these videos.

Understanding state function is vital important in studying Thermodynamic. This are also the key to understand entropy and enthropy.

You made this understandable (amazing)

Thanks, don't know what I'd do academically without the internet!

way better than college explanation thank you so much

That's what i ever wanted! Someone who DOES know how to teach Thermodynamic's law... Thank's God a lot!

Thank You very much. I'm studying for my biophys exam and I was getting pretty helpless until I watched your tutorial..:)

Thank you!!! This makes so much more sense to me now!

you are a gift by god!!! he will bless u sal!!

MOTHER OF GOD I understand it! And just in time for tomorrow's chem test!! Thank you!

you are literally the best teacher ever...

EXCELLENT! Thank you!

already feel better about my exam, thanks!

Wow The best video explanation of not just enthalpy but why we need it and why it's helpful, you won't get this quality education if you paid for it.

I am from India I am just 12 and I need to learn all these but khan bro done this very easy : )

Awesome video, thank you for the effort

what I don't understand is why we need to know all of this. like why do we need to know HOW we get what equals to delta H.

@Rammsteinmaiky1

7 жыл бұрын

You don't have to, if you don't want.

@luisambriz4673

7 жыл бұрын

I think the biggest misconception about school is what we learn is important it is. But what is the most important thing about all these subjects is how you learn, not what you learn. Through learning and going through the processes you learn how to think differently and abstractly rather than the old way of 2+2=4

@NotEvenPerfect

6 жыл бұрын

Hey, let's hope you are not a chemist for NASA now, since if you don't know why it only applies at constant pressure, your spaceshuttles will explode

@victorianunez7113

6 жыл бұрын

Honestly same... I just want to get into nursing school. 😂

@peytonstein8616

6 жыл бұрын

Its less about learning the specific lesson, and more about teaching the learning process. And putting you in situations where you have to learn and think for yourself.

You can rewrite dpv to: dpv = vdp + pdv. Which gives dH = Q + vdp. More compact and you can see immediately what happens when p is constant.

wow...THANKS SO MUCH

Your 10 minute videos teach me more stuff than a 3 hour lesson with my chemistry teacher

@modlexstudies2245

Жыл бұрын

hi

"good old P-V diagram" nice :)

Thank you so, so much! I finally understand this after many years))

"good ol' PV diagram" lol this guy cracks me up, not to mention knows how to explain chemistry topics

i spent all night trying to get this. it took this video for me to actually get it

I tried reading the P. W. Atkins book both in English and in my native language and after 50 pages I was so lost I had no frickin idea what it was talking about. thanks for explaining these things!

I wonder how awesome the teacher was who taught Sal.

Thank you very much for explaining this! I needed this to solve one problem. I've been looking for this for a while. You made my day!

at 10:30 to 11:45 -- If pressure is constant, then delta P is zero. if you have a dP*V, you can't "factor" it to P*dV. dP means "change in pressure", so if you posit that pressure is constant, then dP= P2 - P1 = 0, because P2 = P1. Then you have dP/P = 0 = dV/V, which means that volume is also constant. What am I missing here?

@JayaSaputra

5 жыл бұрын

It's d(PV)= dP*V + P*dV Since dP =0, then d(PV) can be reduced to only P*dV Cmiiw

Make a video on bond energy

you help me soooo much thanks

i love these videos. thanks

Great video love you sal

Best thing avialable on u tube

fun fact: in india their is different sign conventions in physics and chemistry of work done by the system .

he makes it seem so easy...if there is anyone out there that has time can you tutor me..I have in exam next week and if i dont pass it i fail the class. this is the only class that i dont understand.

14 years!!!! thats huge

Thank you very much..

This was awesome

ı am so happy because ı didnt need to listen the lecture from indian engilish. :D

excellent. thank you

FINALLY I KNOW WHAT IS THE ENTHALPY!

Thank you, i thought i wouldn't sleep tonight. This doubt of enthalpy definition was really bothering me.

Why don't you get a separate branch for the Indian curriculum for Chemistry like you have for Physics and Mathematics?? I would be really glad if you take this into consideration.

holy shit this was a great explanation. totally explained my thermo class on enthalpy thanks! The whole reasoning for state properties was huge

Thank you kind sir, although it's a little difficult for me to understand since I'm only in high school chem, this helped a lot, nonetheless.

In the textbook I have.. the first law of thermodynamics is U = q + w not q-w

@Aleu931

5 жыл бұрын

I was about to ask this question

@spectrum792

5 жыл бұрын

@Prachi Sharma what's the difference between work done on vs by the system?

@youdontknowme8818

5 жыл бұрын

@@spectrum792 (considering pressure-volume work) Imagine there is a cylinder filled with gas with a piston. If you apply pressure on the piston, the gas compresses which implies work is done on the system If the gas expands moving the piston upwards it is said that work is done by the system

@guillaumethemapler

5 жыл бұрын

This is because in your book they consider every change in energy from te systems point of view. It is de convention in chemistry. I personaly think its less confusing. A negative q means there is heat taken from the system. A negative w means the work is done by the system. So it loses energy. This energy is now on the surroundings. That is why a negative Delta H is a exotherm reaction. Heath is coming out of the system so the energy content of the system decreases.

@jed2112

5 жыл бұрын

It changes btween chimestry and phy .the point of view is not the same(by/on)

compressing something while keeping the internal temperature in the system the same at all times

Great teacher

meanwhile 49 other people do not believe that enthalpy is the heat content in a constant pressure system

Thank you so much

hahaha, he's such a good teacher. what a good thing.

you have been my savior for my chem test tomorrow

Examkrackers type humor lol. I love it.

Lol Sal's idea of a vacation at the beach is so different from mine.

does this work for constant volume as well?

I didn't understand how constant pressure made all the difference until now. It was an epiphany moment for me.

thanks boss

Sir of Khan Academy, congratulation, you solved a problem of Energy between to conditions of matter, but zero explanation about Enthalpy: how it got there in the first place? Or if you want X, Y, Z didattical introduction and explanation to the the word Enthalpy as defined by the Physics. Then an example defintetly will help.

love it

I cant believe this video is 11 years old

You need to put PV in parenthesis. delta(PV)

Love your videos

God said ..let there be light ..rest is bada bing , bada bong

This video did absolutely nothing to tell us what enthalpy is. but only what enthalpy is during constant pressure

@HitanshuTheBoy

5 жыл бұрын

correct!

When you say deltaPV it would be nice if you would add brackets around delta(PV). Otherwise it reads like (deltaP)*(V)

Just Perfect :)

thank you

@ 10:07 d(p.V) = dp . V + p . dV; at constant pressure (dp = 0), thus d(p.V) = p . dV

@jacobvandijk6525

8 ай бұрын

@@Knipper2000 The non-delta values are the initial values (V1 and p1). Here (0:18), your case of variable pressure and constant temperature is explained. After a full cycle, d(p.V) = 0.

Tyler Dewitt all the way for videos.

Ive just learned from this video Delta pv=P delta V

it can be both, the work done 'w' is negative if the environment does work on the system, and positive if the system does work on the environment.

you say when that heat content would need to be incremented by 2 everytime you go around the path. but wouldn't the equivalent amount of energy be used up by work? as work is equal to heat in closed path? so the heat content should remain the same ryt? someone please answer this!!

good luck on "free energy"!

hello, I have a question! >>>>> so enthalpy is a state variable that defines/expresses the heat content of that state at a constant pressure? which means that at p1 water at some point in the liquid state will have a heat content or enthalpy with a certain value no mater the route it got there>> what are the different possible routes that we can get there? that's what I don't understand, any materials scientists out there???????

Good

is change in internal energy equal to the heat added when volume is constant?

Did anyone hear the sound of a wave at 13:52 when he said sea level?

what happens to enthalpy when pressure of a gas is reduced (joule thomson)

very clear thank you :)

it was explained in the vedio that after each cycle heat content gonna increase in the system, it is right??? then how can we get work from system??

@bagrasweetheart No, it will not work if V is constant. That is because work is equal to pressure times the change in volume. If the volume is held constant, then a change in pressure will not do any work. Remember, the mechanical definition of work is force times displacement. If you push against a brick wall you technically do no work.

@rscottalex I think he should have written the expression using parenthesis: ΔH = ΔU + Δ(PV)

DeltaP = 0 if constant P. You switch from the cycle to a general state. It is, in any case, too fast.

@louyclare wow that was a super good explanation.... couldn't have done it better myself. SO does this mean that Work in an adiabatic system is - or +?

I am still confused , if the enthalpy is state function then why it should increase after completion of cycle( as said in video that heat content is first 4 and then 6 ).

I am a little confused here, deltaPV=PdeltaV say that Pressure is constant at 5 atm and volume is going to change from 6 to 7 liters. wouldnt delta Pressure equal zero if there is no change? then you would end up with zero on the left since deltaP=0 and you would end up with 5x1 on the right because deltaV=1 and P= 5 ?

@ghizlanegzili1695

10 жыл бұрын

deltaPV is delta(PV) not delta(P)*V I think this will clear things up for you! :)

Does anyone know what software is being used here to create the colorful writings and pictures?

@so12what - I had the same impression, but the writings were too "readable" for paint... So there are two options, he either has some pen-like devide or is a heck of good mouse user!!! :)

So, to make enthalpy equals to the amount of heat added we make the pressure constant so that in the calculation we can cancel out W and PV, right? Can you give me an example In real life, in which this condition really applies? Let's say in Energy Conversion thing, like the Heat Pump Cycle or Refrigeration... Really appreciate it, Sir!

if heat is added to the system and system is doing equal work on surrounding then heat is converted to work and it's heat content will be constant after many cycles