online my professor's accent was very strong and they were always coughing in the mic and it was really distracting. These vids are helping for my final exam
@mrhansenable The strength of an acid depends on 1) polarity of the bond 2) bond strength 3) stability of the conjugate acid. Most of the time when you straight up look at a molecue, the stability of the conjugate acid will be the main factor but the others play a role when you're comparing. 1) compare the bond between CH of methane(CH3) and HCl due to electronegativity, HCl is much more polar making it easy to abstract the proton.
@mrhansenable that's why methane is not acidic because the proton is difficult to abstract. 2) compare HCl to HF F is more polar as you know but now we must look at bond strength as well ..down the groups on the periodic table, bond strength increases as you go up because essentially the atom is smaller, the positive protons in the flourine nucleus are closer to the valence electrons and thus a bond will also be closer and more stable or strong. Thus the bond between HF is more difficult
Plus or minus a proton is the key to understanding conjugate acid/base pairs... If some prof, or a chem textbook had told me that like 8 years ago, i wouldn't need to be here watching this video
2) acidity also depends on the H-E bond energy when bond energy is a smaller value acidity increases as it is easy to break the bond (as you go down the group atoms get bigger so the bond length become higher and bond become weaker that is because when bond length is long u get weaker pi orbital overlapping ) soo according to that HF is the weakest acid in group 7 so HF is a weaker acid than HCl,HBr,HI and also HF has strong H bonds which make it even weaker
Usually, a conjugate of a weak acid is NOT a strong base. Ka * Kb = 1*10^(-14). From the formula you can calculate that for example HCO3- ¨s conjugate base's Kb is only 2.1 * 10^(-4) which means that it's not a strong base. I think you could say that the acid is a weaker acid than it's conjugate base is as a base. However if we count H2O as a weak acid, we can use the same formula to check it's conjugate base's Kb which is now over 50. I would say that the conjugate is only rarely a strong base.
@mrhansenable thus making HF a weaker acid. 3) this is mostly what ties things together...the strength of the conjugate base. If you look at HF the conjugate base is F- Molecules, atoms don't like to have charges on them, correct? Electron density caused by the net negative charge makes the atom destabilized. F is much smaller than Cl (know periodic trends!) Thus the negative charge destabilizes it more than it does Cl-. Same net charge on a smaller atom is worst. On a larger atom
@mrhansenable on a larger atom such as Cl- the negative charge has a larger area to move around in (more polarization), thus making it more free and less cramped (to put it simply) Thus HF is a weaker acid. Remember, the explanations are based on trends..notice when i say "strongER" or "weakER" or MORE polar "LESS polar ...much of this is relative ..only when you're comparing different atoms. acid strength for hydrohalogen HI>HBr>HCl>HF same explanation for each.
strong acids and bases make VERY WEAK conjugate bases and acids, respectively, you're right. but weak acids and bases still make weak conjugate bases and acids (respectively), only THESE conjugate bases and acids are LESS WEAK than those formed from strong bronsted-lowry acids and bases. so overall they all form fairly weak conjugates but those formed from STRONGER bronsted-lowry acids or bases tend to be RELATIVELY WEAKER. hope this helps!
@sonnytrujillo nop, weak bases form conjugate weak acids. you book does not lie, but neither does the video. if the acid yielded by a weak base was strong, it would dissociate completely which means that the resulting conjugate base would not be strong enough to grab H+ therefore its effects would be considered neutral. that would not make sense because we know that the base in question (although weak) is strong enough to react with water and grab one of its H+. (hope that helps!)
@MrMetacognition That's not necessarily true. A weak acid could have a week conjugate base. However, the weakER an acid get's, the strongER it's conjugate base. Similarly, we could say the StrongER the Acid, the WeakER the base. Infact, the conjugate bases of Strong aces are so weak that we consider them to be neutral species.
subscribing right fucking NOW, so good , you have no idea, my teacher from turkey suck DIIICK at explaining and the book is a little confusing, this takes knowledge that I pretty much know and really ties it in to the big picture, thank you khan academy no joke,
Not necessarily. Take, for instance, acetic acid. The conjugate base of this weak acid is indeed a weak base. Therefore, it is just as correct to say the conjugate base of a weak acid is a weak base as it is to say the conjugate base of a weak acid can be a strong base. Simply take the acid/base into context.
well he does get paid from(yt google! and i hope a lot of ppl are donating to him! and imo he should win a nobel prize! what's more nobel than free knowledge?
Actually.. saying a weak acid will produce a weak conjugate base is a common fallacy in many chemistry textbooks. Its a dumbed down version of the truth. A weak acid can have a weak conjugated base or strong conjugate base. Acid strength is on a log continuum with conjugate base strength on the y axis. What determines the conjugate strength is its Kb. But A strong acid definitely produces a weak conjugate base.
Why is HF a weak acid but HCl and HBr are strong acids ? Doesn't this have to do with electronegativities? F is more electronegative than the other two meaning they snatch up protons from H2O. But the electronegativity of oxygen in OH- is pretty high too right?
mrhansenable hf is a weak acid compared to the others because f- is a smaller cation where as the others have a larger cation making them more stable. The more stable the more acidic. And remember going down a column has a greater acidity because of size of the cation
Again the mistake with the fluorine symbol... please make the correction. The videos are very nice and clear but It's not good to find these kind of mistakes, the idea is to teach people in a cool and good way not to promote these misinformation in the students. I love these videos, with few corrections would be perfect! :)
Man who does this stuff for Khan Academy..... you are wonderful. i hope you know how many degrees and successes you have contributed towards....
his name is "Sal Khan" and thats what he dreamt anf aimed of doing
So true !
@Snoop Log the guy named snoop log, the man we didn’t deserve and we didn’t need whatsoever
@@alyx1a Niggaz finna pounce after smoking this ounce
haha, i like how he writes fluorine as Fl. At least he caught it.
haha was thinking the same thing!
After 3 years of crappy teachers trying to explain this idea, I have found 1- 17 minute video that cleared it all up. Thank you, you are a God!
man, keep doing what you do. you taught me this in 17 minutes. my teacher took 2 months and i learnt nothing
What's also impressive is that the RUclips Interactive Transcript is always correct for Khan... his pronunciation is immaculate. xd
Thanks Khan!
your lessons are the best on youtube. i wish i knew about them 2 days before my test and not just one
You are amazing, i cannot thank you enough for all your help with my Chemistry, Physiology , and Microbiology classes. Wonderful work!
online my professor's accent was very strong and they were always coughing in the mic and it was really distracting. These vids are helping for my final exam
its an awsum video.....real "concept clearer"....n espcly d conjugate part was such a cakewalk....when Sal taught it....thnx...
Truly saved me! Bless these videos!
Thank god for Khan Academy!!!
Very very helpful :)
@mrhansenable The strength of an acid depends on 1) polarity of the bond 2) bond strength 3) stability of the conjugate acid. Most of the time when you straight up look at a molecue, the stability of the conjugate acid will be the main factor but the others play a role when you're comparing.
1) compare the bond between CH of methane(CH3) and HCl due to electronegativity, HCl is much more polar making it easy to abstract the proton.
very helpful videos, but just a little correction on this one, conjugate pairs have inverse relationship...strong acid to weak base and vise versa =)
i really for the first time got the concept of conjugate
@mrhansenable that's why methane is not acidic because the proton is difficult to abstract.
2) compare HCl to HF F is more polar as you know but now we must look at bond strength as well ..down the groups on the periodic table, bond strength increases as you go up because essentially the atom is smaller, the positive protons in the flourine nucleus are closer to the valence electrons and thus a bond will also be closer and more stable or strong. Thus the bond between HF is more difficult
you should have used a hydronium ion instead of a floating proton, it balances the equation and makes it easier to follow
Plus or minus a proton is the key to understanding conjugate acid/base pairs... If some prof, or a chem textbook had told me that like 8 years ago, i wouldn't need to be here watching this video
Thanx Sal! We really owe you man! ComedicToast, KHANJUGATES hahahahah! very funny!
i thought that strong acid it has conjugate of weak base
and strong base has conjugate of weak acid
At 3:10, the captions: "increase the concentration of [UNINTELLIGIBLE]"
Lmao!!
aha !!! I see what it is all about ))))
thanks for such great video !!!
No, his statement is true. I'm writing this right from the chemistry book "The conjugate base of a weak acid is a weak base."
Was very confused on the conjugate part when reading the book, Completely cleared it up. Great videos
8:27 so the conjugate of H3O+, does that make the H2O conjugate base H2O-? Do you have to write the +/- sign on the molecules?
Thank you so Much, your videos are really helping me understand the material. Keep up the amazing work!
2) acidity also depends on the H-E bond energy
when bond energy is a smaller value acidity increases as it is easy to break the bond
(as you go down the group atoms get bigger so the bond length become higher and bond become weaker
that is because when bond length is long u get weaker pi orbital overlapping )
soo according to that HF is the weakest acid in group 7
so HF is a weaker acid than HCl,HBr,HI
and also HF has strong H bonds which make it even weaker
this really broke it down for me. thanks so much.
I liked this lesson it was very easy and it will help me in my exams thank you soo much😊
As always, you are a godsend!
16 minutes to teach something extremely well that my teacher took a week to teach badly -__- thank you
THANKY YOU SO MUCH I UNDERSTAND EVERYTHING NOW
Sir, THANK YOU!!!!!!
Usually, a conjugate of a weak acid is NOT a strong base. Ka * Kb = 1*10^(-14). From the formula you can calculate that for example HCO3- ¨s conjugate base's Kb is only 2.1 * 10^(-4) which means that it's not a strong base. I think you could say that the acid is a weaker acid than it's conjugate base is as a base.
However if we count H2O as a weak acid, we can use the same formula to check it's conjugate base's Kb which is now over 50.
I would say that the conjugate is only rarely a strong base.
@mrhansenable thus making HF a weaker acid.
3) this is mostly what ties things together...the strength of the conjugate base. If you look at HF the conjugate base is F- Molecules, atoms don't like to have charges on them, correct? Electron density caused by the net negative charge makes the atom destabilized. F is much smaller than Cl (know periodic trends!) Thus the negative charge destabilizes it more than it does Cl-. Same net charge on a smaller atom is worst. On a larger atom
omg I FINALLY GET IT MORE. THANK YOU
i like the way he highlights ammonium, and ammonia, kinda funny :))
Thanks these tutorials are a great help!
thank you very much...
it's very nice explanation..!
thnx for fillin up the holes in this concept for me :) really THNX ALOTSZ!
Awesome! Thank you so much. Practice problems are always helpful!
thank you, thank you, thank you!!!
wow incredible! thank you so much for this video
You are the best!! Thanks for the videos :)
Thanks🙌
@mrhansenable on a larger atom such as Cl- the negative charge has a larger area to move around in (more polarization), thus making it more free and less cramped (to put it simply)
Thus HF is a weaker acid.
Remember, the explanations are based on trends..notice when i say "strongER" or "weakER" or MORE polar "LESS polar ...much of this is relative ..only when you're comparing different atoms.
acid strength for hydrohalogen HI>HBr>HCl>HF same explanation for each.
Thanks Sir! I played the whole vid n getting the grasp of it! :)
thank you nerdy but chill guy
thank u great video!!!!!!!!!
thank you man, that was so helpful and so easy thanks!
nice one
What program does he use in the video?
strong acids and bases make VERY WEAK conjugate bases and acids, respectively, you're right. but weak acids and bases still make weak conjugate bases and acids (respectively), only THESE conjugate bases and acids are LESS WEAK than those formed from strong bronsted-lowry acids and bases. so overall they all form fairly weak conjugates but those formed from STRONGER bronsted-lowry acids or bases tend to be RELATIVELY WEAKER. hope this helps!
@BF1 thx for info...
But the real question is, is C3PO the conjugate base of R2D2?
God bless you!
Best voice.
Thank you so much!
You made my day!
@veiledmaiden Sal corrects himself @ 2:33
@vukbui1987 doesn't the trend of conjugate bases decreases as we go down the group of the Halogens?
Just wondering. THanks.
Thank you.
gosh. thank you so much.
Would there not be a reverse reaction for the chlorine ion because it has an octet?
@sonnytrujillo nop, weak bases form conjugate weak acids. you book does not lie, but neither does the video. if the acid yielded by a weak base was strong, it would dissociate completely which means that the resulting conjugate base would not be strong enough to grab H+ therefore its effects would be considered neutral. that would not make sense because we know that the base in question (although weak) is strong enough to react with water and grab one of its H+. (hope that helps!)
I thought Strong Acids/Bases have Weak Conjugate Acid/Base. While, Weak Acids/Bases have Strong Conjugate Acid/Base... any comments?
That's what I was taught too! Now I'm confused. :(
thats true and right
TBH, sometimes these videos seem to go against what my professor tells us
Yes, i have also read..
Thank you so much
Burn the chem book. Sal is the master of chemistry.
@MrMetacognition That's not necessarily true. A weak acid could have a week conjugate base. However, the weakER an acid get's, the strongER it's conjugate base. Similarly, we could say the StrongER the Acid, the WeakER the base. Infact, the conjugate bases of Strong aces are so weak that we consider them to be neutral species.
subscribing right fucking NOW, so good , you have no idea, my teacher from turkey suck DIIICK at explaining and the book is a little confusing, this takes knowledge that I pretty much know and really ties it in to the big picture, thank you khan academy no joke,
Thank you man, saved my IB
Thanks
Not necessarily. Take, for instance, acetic acid. The conjugate base of this weak acid is indeed a weak base. Therefore, it is just as correct to say the conjugate base of a weak acid is a weak base as it is to say the conjugate base of a weak acid can be a strong base. Simply take the acid/base into context.
well he does get paid from(yt google!
and i hope a lot of ppl are donating to him!
and imo he should win a nobel prize!
what's more nobel than free knowledge?
thanks alot
Actually.. saying a weak acid will produce a weak conjugate base is a common fallacy in many chemistry textbooks. Its a dumbed down version of the truth.
A weak acid can have a weak conjugated base or strong conjugate base. Acid strength is on a log continuum with conjugate base strength on the y axis. What determines the conjugate strength is its Kb.
But A strong acid definitely produces a weak conjugate base.
shouldn't "F = OH + HF" be "H2O+F=O+HF" ?? or do you not have to specify it because of the (aq)?
thanks!
currently doing so bad in physics that when he wrote Fl for fluorine... I was like yup that looks right.
I really didn't get it till the end portion lol good video though 👍
I understood that 15 years ago, flourine has symbol Fl you see how dynamic science is 😅😅
@eboueboy1122 No, its a week base, those that have hydroxide ions (NAOH) are strong bases
where can i find the first video about this acid thing PLEASE , and thank you so much BTW
Doesnt strong acid have its weak conjugate base pair?
Since the base doesnt have tencdency to re-aceept the proton?
@vukbui1987 but isnt Fluoride ion a strong base?
Yes it does
thanks
can the same compound have a conjugate acid and a conjugate base please ?
why don't you put h20 in your equations? It really throws me off
gosh i really like your videos but your voice is so soothing i fall asleep every time..or maybe its the topic im not sure -_-
Why is HF a weak acid but HCl and HBr are strong acids ? Doesn't this have to do with electronegativities? F is more electronegative than the other two meaning they snatch up protons from H2O. But the electronegativity of oxygen in OH- is pretty high too right?
mrhansenable hf is a weak acid compared to the others because f- is a smaller cation where as the others have a larger cation making them more stable. The more stable the more acidic. And remember going down a column has a greater acidity because of size of the cation
@tom2king Yeah, I noticed that too.
Is this the lewis acid & base?
Go up, next to the subscribe button, click the "Videos" button. It should take you to the playlist. That's what I did; hope it helps!
In Coach Rhodes' Class
I know easier way to get the pH or pOH level of a substance: Universal Indicator lol. Thanks for vid it helps in Science a lot
There's also Flerovium now, which is actually Fl.
Isnt HF a strong acid would produce a congjuate weak base?
I have a big problem after 2years studing at high school, you solve all my problem in 104 video😂😂😂
Again the mistake with the fluorine symbol... please make the correction. The videos are very nice and clear but It's not good to find these kind of mistakes, the idea is to teach people in a cool and good way not to promote these misinformation in the students.
I love these videos, with few corrections would be perfect! :)
He corrected that in a later video.
@Yznitzka He isn't writing with a mouse...He is using a digital pen.