I have been trying to understand for almost 4 years now. I actually finally get it and it feels amazing. I don't think you know how much you are changing lives!

This guy is awesome. Only 30 minutes ago, he was helping me with multiplying matricies, and now he is helping me with chemistry. I love it. :)

This video series saved my chemistry grade this unit. A two-hour lecture and meeting with the teacher after school didn't stick, but somehow this made everything click. Thank you!

You just made my whole semester of chemistry obsolete. I thank you for that.

OMG. If i had found this like 2 hours ago, so much time would have been saved. Thanks so much, this was very helpful.

Welp, I might fail my chem test.

One of my chemistry teachers spent 2 weeks trying to explain that to me, and pretty much failed-- and this video simplified it WAY more than he did.It makes sense now! Thankyou.

Oh my goodness, it feels as though the world all makes sense! Thank you so much for helping me out with Chemistry! If I ever get stuck again, I will definitely come back to watch more of your videos.

Chemistry exams in 22 hours and i couldn't figure shit out of this until i came across your video, what a relief....thank you Mr Khan :)

How I wish all teachers talk in moderate speed and a lot of patience like you Mr.Khan

Mr. Khan, Saying you videos are helpful would be an understatement. The only thing I would like to see more, which you do in some videos, is a brief overview of the general steps/equations used. I find this extremely helpful especially in the longer videos that have a lot of content. Keep it up!!!!

this video remains great after 9 years! #teamkhanacademy

Where have you been all my life GREAT explanation.. i understood first time round.

My Chemistry final is tomorrow. I have learned more in watching Khan academy for the past 2 hours than I have learned in an entire year of class. --Speechless--

thanks man great explanation! looks like i dont have to fail chem this year! :)

The best part of his videos is the fact that they're videos, pause, replay etc, etc.

no matter what i am trying to understand i come to khanacademy and everything is understood so clearly, i wish you were my professor!!!!

Your video confirms that I know what I'm doing. Thank you =)

Slight arithmatic error, 6x-1714.98=_1714.98, the video was still very useful for my exam, thanks :)

thank you soooooooo much, i've been sit in my chem class since school starts and now i understand everything just by this 15 min video..

thanks it helps me understand more. Can you talk about different types of enthalpies such as atomisation, bond, enthalpy of solution, lattice enthalpy.

You my friend, are a life saver. I have A Level Chemistry coursework tomorrow afternoon and all I know is it's on enthalpy changes....which I knew hardly ANYTHING about before this. I couldn't sleep last night because I was worried I wasn't going to understand it. This video has helped so much. Thanks enternally :)

You prove why all teachers should be fired and why we should simply learn from amazing teachers at home like you.

God bless you, seriously. I had this concept explained to me by so many people but I did not get it until I actually stumbled upon this video. I wish I had known about this channel at the beginning of the semester.

your voice is strangely soothing

this really helped, thanks!

thanks really helpful. as the other person mentioned, if only I had found it 2 hours ago.

no one else can explain it properlt, thank you for simplifying and not using unnecessary arrows all over tha place

I missed a lecture on this topic and understanding it mainly on the textbook was kind of complex, but after watching this simplified powerful video with examples, I am now adept at this topic!!!😍 thanks so much

Holy shit, now it's clear to me. Thank you!

back to this video. i bombed this last test because my professor drops the lowest grade and i already did well on the other ones, but the final is next week!!! need to understand this video.

the propane is in a gaseous state, not liquidous.

just got an A- on my AP Chem final. Couldn't have done it without you

this was REALLY helpful i have been studying this for two hours and didn't get it then in 15min i completely understand thank you!

Test tomorrow! You made all of my studying make sense. It's all clear now. :)

Thanks!, Very helpful!

U make me regain my confidence in understanding this.... tear*

great explanation!! I should start skipping my chem class and watching youtube teaching videos instead, I would probably learn more. Thanks for the video!

its so fun and easy watching you videos that it doesnt even feel like im studying, even though im learning stuff like crazy xD

THANK YOU SO MUCH!! u finally cleared my confusion. I go to the (currently) 4th best skl in the UK nd my chem teacher is still could get this through my head but u done it 15mins lool

8:58- 9:10 = hilarious calculator indecision. Sal you crack me up.

great! thank you for the valuable knowledge!!!

u da BOSS ... i was absent the day my teacher taught this.. ty for explaning

You may have just saved my life! Thank you! I haven't been sure how to even begin studying but this has helped

OMG! Dude u rock man. I didnt understand a thing during my lecture earlier. After watching i understand now. Thanks to you. You should be a professor:)

Wow this video was great! Thanks so much

I did find that helpful. Thanks Sal.

@Pablothe you should probably make a video showing everyone how to do Thermochemistry now...

Thank you so much, Dr. Khan! You explained it a lot better than my teacher.

@shatzE3 Rewatch it and listen to him carefully, Water is - 285.53, his - and 2 just combined so it looks like plus. Easy mistake to make though if you didn't hear him or watch him pick it off the list.

You are a legend sir ❤️

this video makes my life easier, thank you mr. khan

I don't know why I even bother going to class I learn more watching these.

KhanAcademy, thank you very much for these tutorials. They've saved my arses many times over.

if it was not for you this semester i would be failing college chemistry, keep up the good work sir

Saved my chemistry as level! Thanks:)

I understood almost nothing till I watched this video. I wont fail my test tomorrow! Very Grateful!!! :D

YOUR ARE MY HERO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Amazing lesson!! I was strugling with that all night until i saw your video! thank very much!

great video i learned more in 16 min than i did in a week

For the combustion of propane you would get water vapor, your state on the water should be gas.

YEEESSS!!! Now it makes sense! Thank You :) :)

i had to stand up and clap for 5 minutes after this video out of amazement

full clarity .explained very well.thanks

YOU ARE A GOD!!!!!! THANK YOU SOOOOOO MUCH!!!! YOU ARE GOING TO SAVE MY HONORS CHEMISTRY GRADE :-)

you are my second ap chem teacher!

You may have just saved my life! Thank you!

studied 2 week @school. 15 min with khan academy

You sir, are better than my disgusting Chemistry teachers. Kudos to you.

your voice is interesting...but at the same time soothing haha

This was so helpful, THANK YOU SO MUCH! you have saved me from hours of confusion.

Thank you for all of your help. When I'm rich I will donate many treasures to you.

you are amazing! thank you so much

Why was the 285.83 a negative when you multiplied it in your calculator?

Here, propane is in the gaseous state, whereas, it was in the liquid state in the table that is given, so how can enthalpy of formation for both liquid and gas be -104.7kJ/mol

thank you! I might actually pass Chemistry now! My lecturer sucks :/

Omg thank you so much. This actually made sense to me.

"Hope you found that helpful"...are you kidding me, just helpful? you are a hero indeed!

Thanks man. You’re gifted

This video helped me a ton, thanks

can u pls tell me how to calculate the enthalpy of combustion of glucose . thank u.

that was so helpful! thank you so much khanacademy! :D

thank you dr. khan. you make learning fun

My god, your videos always save me!!! Thank you so much

Fantastic

I want to meet u :( u are sucha genius! :o

you are #1 in my book

now i totally get it, thankyou so much :)

This made this so much easier, Holy shit!

Thank you very much

@DarkWhisper07 yes , cuz all of us are same . he can'nt learn in class as much as he can learn while actually listening it to it 100% and in room ALONE by himself

thanks it helped me a lot

God bless your soul Sal

THANK YOU GOOD SIR

Great

very nice video thanks

Khanacademy you make the teachers looks bad... In a good way! :D

thanks for the video

7 years laters this video still a saver

Thank you