Specific heat, heat of fusion and vaporization example | Chemistry | Khan Academy 

I couldn't understand this at all in chemistry but now I'm like "oh, yeah, that makes sense" THE CHART HELPS EVERYTHING

Sal, your voice makes everything seem so easy to me . Thanks!!!!

I know this video is quite old, but thank you so much!! For some reason teachers love to give very vague lessons. This really helps clear up all the little things!!

First line: "a couple of video agos we learned.." lol i still love your videos and appreciate your attempt to give students an intuitive insight on the subject matter

Why is my chem teacher getting paid more than Sal?

The voice, turning complexity into simplicity and great sense of humour, made me watch this video from the start to the end! Thank you Sr.

Man this guy has MASTER degree in EVERY F***** subject, with technical education.

I wasn't in class when this topic was taught, and I didn't do well on the test. I have my midterm tomorrow so I was looking up videos to teach me and know it all comes to me so easily! Thank you Kahn Academy!

Am watching in 2018 and thnx for that mistake it really help to show if i was following or not

You're amazing. Again, a fraction of a period of Chem class and I learned so much more...

I'm pretty sure he should have used moles instead of mass when using the equation regarding phase change (vaporization/melting). Because mass would not cancel delta H (KJ/mol), only moles will. and the equation for q is "q = n X delta H (vap) NOT "m X delta H". where n is moles not mass. He seems to be correct for heating up/cooling down a phase, using mass as the q. Because, that equation is "q= m X C X delta T". Does anyone agree? if so, like so they can see and update this video. source- "principles of chemistry text book 2nd edition".

Did 333.55 switch to 335.55 by mistake when you did the calculations?

@Maishir Yes, the Celsius and the Kelvin scale are essentially the same, except 0K is -273.15*C so the kelvin scale starts at a lower point but the amount of heat you need to add to increase by 1*C or 1K is the same - (or for liquid water, 4J) inb4 confusing

Yeay I was listening! I thought he forgot, then I thought it was just me, then he said \o/

Thank you very much. This topic was so dry for me, but now it is interesting.

Thanks so much, got me to understand heating curves more and what happens when you add in a certain amount of energy into the system. Homework accomplished :)

Sal you said that the Hf was 333.55, when you did the problem you multiplied it as 335.55*200 and it gave me a wrong number when I did it with the initial Hf you gave (333.55).

Error: You used two different figures for heat of vaporization! 335.55 and 333.55

ahhh! Thanks so much! i finally understood this stuff :]

I cannot thank you enough for all your videos. I have used them for Physiology, Chemistry, Microbiology, & Physics. Always so helpful, clear, short and sweet! You are awesome!

At ~9:50, why does he not go through heat of vaporization? Also is the value of Hf 333.55 or 335.55?

Thank you this was extremely helpful 😀

it isn't the same. for the equations, you are only interested in the CHANGE in temperature. The DIFFERENCE from -10 degrees C to 0 degrees C is the same as 263.15 K to 273.15 K: 10 degrees.

Thank you so much,,, I understood this so fast!!

YOU'RE THE MAN! THANK YOU SO MUCH

final exams next week and Thank God for youtube teachers

So actually you told that the heat of fusion is the amount of heat required to take away yo fuse 100°C ice into 100°C water, it's not 100°C, it's 0°C ice to 0°C water... Yes and you're the best teacher I've ever had🛐

THNX internet is the best tutor of the world :P

U just helped me understand something that took a week for me to even get enough interest to try in school. Come to my school and be a chemestry teacher please. :)

lol I love how he trolled us and left out the fucking biggest amount of energy in the formation of water vapor. then he's just like "oh uh looks like I forgot that little detail " lmao

we memorise these values or they already given in the question? specific heat values ? (solid liquid and vapor )

My college instructor couldn't explain this in this way at all. I could not understand the difference between specific heat and heat of fusion until I watched this video. Thanks! I don't know why teachers (seem to) think that the way to make a class a challenge is to explain things cryptically. I have to see the whole picture to get it. Learning deficiency or not, if teachers want to force the archaic model on people, they should not be teachers.

Lattice structure is introduced while describing enthalpy of fusion of h2o without being described.

I love you sooo much!! my teacher is terrible at explaining things, but I can see clearly now xD THANK YOUUU!

7:18 , did he change or make a mistake on the number of *heat of fusion* that is *(333.55)* writing it he like 335.55? Because sins that its totally diferent the results. Please tell me, I am confused...!

THANK YOU SO MUCH!!!! This finally makes sense!

Why didn't he work out the step from 100 degree water to 100 degree vapor? Since he worked out 0 degree ice to 0 degree water....

@PaulRyan2k no its chemistry, it deals with the change in the specific heat of elements. We're learning about it now in AP chemistry.

I wish this was explained to me like this years ago! 😢 😊

Do you know everything!!!?? THANK YOU!!!!!!

you are awesome these videos are logical and help me understand thanks bro

thank you!

it finally makes sense! thank youuuuuu sir!

should he have used Kg? as thats the SI unit?

Your videos are awesome Sal! Thanks for saving the day again :)

Thank you so much Sal this video was very very helpful. Have a test tomorrow on this and thanks to you I feel much more prepared.

Thank you sir, for helping me with my homework.

Love your videos and thank you😆😆

Thanks so much for this!

thank you

October 2019 🙋🏻

Thank you so much! Now I won't fail my test!

@khanacademy I have to be honest, you are the reason i'm passing physics.Thank you.

Damn, I need to stop watching these to do chemistry homework. My chemistry class is stopping me from learning chemistry. How ironic.

god bless the youtube teachers

When I learned this in class, for the segments that the phase changes take place. So for segment B and D, where melting and vaporization take place. The formula I was given was the number of moles x delta H fusion, and moles x delta H vap. Is this still the same???? I am confused!

This was very helpful, thank you

thanks for the info.

@Sushiarushi That's weird, because in my course it's in my Physics, not my Chemistry book. Oh well :P

Super helpful

1)do i have to go the very same procedure if the graph starts at the horizontal axis? 2)there is no alternative method of doing it,for instance dpoing it in one line by taking out the common factor which is the mass?

very, very, very! helpful.

Thanks khan, I hope my comment is read by uni physic lecturers. you all have to learn to teach from Khan...(not all but most of the lecturers)

I got a chemistry test in 18 minutes on Heat Fusion Heat Flow H charts etc AHHHHHHH

Because Latent Heat (Heat of Fusion and Heat of Vaporisation) occurs after each change in phase and the formula is Q(Energy)= Heat of Fusion * Mass

@Violetavrie ya- 373 K = 100 degrees C :)

@caribbeansuntrue all of his constants are in grams, so no problem. He does get the definition of fusion backwards though. Fine video mostly. Easy to understand when you can rewind and play again and again...

I get this video, but it would be better if conversions are done to show that the measurements are actually canceling out before arriving to the final answer. And I notice that the heat of fusion value used midway in the video was incorrect because at the start of the video, what was written is 333.55 J/g, but what was used is 335.55 J/g.

COOL VID..gr8 job in educatin ppl~

I just adore you

thanks for your comment, i was wondering how come he didn't convert to K ... but i now noticed the difference is the same ;)

Well done!

Thank you so much. I wish kahn academy could be my teacher.

My teacher shud learn to teach from you guys

Why does the anion have no affect on the color of a flame in the flame test?

I have a question probably a stupid one but nevertheless here it is: Once the ice is heated enough it turns into a liquid shouldn't we change metric system? after all aren't liquids expressed in Liters?

Thank you so much this helped a lot!

@Violetavrie for specific heat yes

Thanks a million! Best explanation yet!

Thanks A LOT!!!!!

I knew it!! you had forgeten to make the calculation from 100degree water to 100degree vapor... I was starting to get confused, hahah

@1aliceinchains I'm doing the course this year :)

@apasionadagatinha Because it's the temperature change, 0 - - 10 = 10

Thank you so much Mr.Khan :)

I think what you're referring to is a bose einstein condensate.

And then I only have 3 minutes to do this problem in reality... That's about how much time our instructor gave us to solve this type of problem. Time is up, and finger is crossed.

I don’t even know if my chem professor knows how to do this, he just sends these videos.

OMG thank you! :)

If heat does not rise while undergoing fusion or fission, what is happening to the atoms and molecules when the energy is being applied to the system? If they are not vibrating more and creating more heat, how is the energy affecting the atoms?

It takes so much energy to go from 0 degree ice to 0 degree water and 100 degree water to 100 degree vapor

@SirMaarten314 No question is a stupid one. ;-) You would not make this conversion because grams measures weight while mL an L measures volume, two completely different things. Also grams is metric already XP.

Thanks man!! :)

So... Kelvin and Celsius are interchangeable?

Anybody studying for finals????

Very good

great video.

How is pressure involved in this whole process?

thnx bro

3:00

Sal! Thank you! The visualization really helps to see what q = mCs∆T really is and what it's doing. Something clicked, thank you!