Unbelievable video always struggled with buffers due to the questionable teaching methods by my teacher. Thanks to this man I shall walk into my A2 exam with confidence.
Phenomenal video - genuinely so much easier spending 10 minutes watching these videos as opposed to trying to process the content of the text book (which are generally very poor)
Wouldn’t the equilibrium shift to the right for when acid is added to the acidic buffer, as the addition of H* ions will make more CH3COOH, so to counteract this change the equilibrium will shift to the right to produce more CH3COO- and H*. Could you help me out with this I am a bit confused.
i think it’s because it forms more CH3COOH on the RHS so to equal out the concentrations it shifts to the left, i’m not sure, this is how i remember it though.
Learn definitions of buffers (weak acid or base PLUS its corresponding salt) and weak acids/bases (ie only partially dissociate into H+ or OH- ions in water hence WEAK, so establishing an equilibrium/reversible reaction with them). Then apply LeChateliers principle - which is just like negative feedback mechanism in biology. Homeostasis is the term used to describe 'keeping things the same' - for example body temperature (an internal thermostat) or blood pH. Carbonic acid/hydrogen carbonate ions in blood is great example of an acidic buffer, which can resist SMALL changes in pH maintaining blood pH around 7.4 (vital to staying alive!). I hope that helps to give context for learning/understanding buffers! With regards to basic buffer though, you just apply LeChateliers principle in the same way as you would for acidic buffers - since XS OH- ions are added, the equilibrium must shift in the direction to OPPOSE this action(ie remove the XS OH-). So SOME (but not all) of the ammonium ions NH4 + present in solution (formed from both weak base ammonia and its salt) react with the XS OH- ions to reform ammonia NH3 (and water H20), so shifting equilibrium to the lefthand side. In this way, a buffer maintains a constant pH - but only for SMALL additions of acid or alkali! I hope this helps to clarify as buffers are tricky I know!
Thank you for the video, however I don’t get why the solution has to be a buffer solution in the situation where e.g OH- is added to an acidic buffer, cause the conjugate base from the salt doesn’t play a role in the reaction in resisting the change in pH
Am I correct in saying when you add an X-moles of acid to an acidic buffer, the moles of acid increase by X and the moles of salt decrease by X? ( And vice versa for adding an alkali to an acid) And then those new mole values are what you use for Ka calculations? Thank you :)
12:00 i dont get whats being opposed. surely if OH- reacts with NH4+ then you are reducing the concentration of NH4+ so i would assume the equilibrium shifts right to make more of the NH4+ thats been used up by reacting with OH-?
A buffer solution means resisting change in Ph right? So when an acid(H+) is added to that solution, the H+ reacts with the COO- and produces a higher concentration of COOH? Doesn't this mean the value of Ph decreases?
+Aashish_Menon Yes that's right. But remember pH is a measure of H+ ions. COOH dissociates weakly and hence does not produce many H+ ions. For this reason the pH value doesn't go lower. Hope this helps?
+Allery Chemistry Hi, I'm really confused about a certain part in the acidic buffer section. How come CH3COO-NA+ dissociates completely? I thought that for an acidic buffer, the salt has to be weak as well?
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This video was made 8 years ago, but still an INCREDIBLE VIDEO!!! I understood more in these 12 minutes than I have in my entire 2 years of A-level.
Thanks! Chemistry doesn't really change much at A level especially buffers, seems to be an exam board favourite!😀
you're actually the best chem teacher on youtube, and your videos are consise and quick, so helpful for last minute cramming lol, thanks so much
You're very welcome!
Unbelievable video always struggled with buffers due to the questionable teaching methods by my teacher. Thanks to this man I shall walk into my A2 exam with confidence.
such a life saver!!! you make it so much simpler! thank youu :)
Phenomenal video - genuinely so much easier spending 10 minutes watching these videos as opposed to trying to process the content of the text book (which are generally very poor)
Thanks very much 😀
Wouldn’t the equilibrium shift to the right for when acid is added to the acidic buffer, as the addition of H* ions will make more CH3COOH, so to counteract this change the equilibrium will shift to the right to produce more CH3COO- and H*. Could you help me out with this I am a bit confused.
i think it’s because it forms more CH3COOH on the RHS so to equal out the concentrations it shifts to the left, i’m not sure, this is how i remember it though.
fab video. you made it really easy to understand and I got it first time around.
Perfect explanation.. A tricky concept made SIMPLE! ty
watched so many vids on the topic this defo was the best one thanks
Thanks 😊
Thank you! You saving my academic life 6 years later!
You are so welcome!
Very well explained, thanks 🙂
Absolute Legend!
Thank you for this really useful video. Hoping to see more videos in time for exams :)
You're welcome!
Truly outstanding video you taught me better about buffer than my teacher, keep it up😌
sir you are amazing !! no better explanation ! thanks a lot
for the basic buffer when you added alkali why did the equilibrium shift to the left?
Zak z I am also confused about this...
Because the OH- reacts wit the NH4+ to form NH3 and water bish
to remove the excess OH- ions from the solution and keep the pH constant
Learn definitions of buffers (weak acid or base PLUS its corresponding salt) and weak acids/bases (ie only partially dissociate into H+ or OH- ions in water hence WEAK, so establishing an equilibrium/reversible reaction with them). Then apply LeChateliers principle - which is just like negative feedback mechanism in biology. Homeostasis is the term used to describe 'keeping things the same' - for example body temperature (an internal thermostat) or blood pH. Carbonic acid/hydrogen carbonate ions in blood is great example of an acidic buffer, which can resist SMALL changes in pH maintaining blood pH around 7.4 (vital to staying alive!). I hope that helps to give context for learning/understanding buffers!
With regards to basic buffer though, you just apply LeChateliers principle in the same way as you would for acidic buffers - since XS OH- ions are added, the equilibrium must shift in the direction to OPPOSE this action(ie remove the XS OH-). So SOME (but not all) of the ammonium ions NH4 + present in solution (formed from both weak base ammonia and its salt) react with the XS OH- ions to reform ammonia NH3 (and water H20), so shifting equilibrium to the lefthand side.
In this way, a buffer maintains a constant pH - but only for SMALL additions of acid or alkali! I hope this helps to clarify as buffers are tricky I know!
Can i ask, for the basic buffer H+ and OH- reaction wouldnt it affect the overall pH?
Why does the equilibrium shift to the left when you add hydroxide ions to the basic buffer? Thanks for the videos😊
thank you sir, great explanation
Thanks a lot it really helped out🤗🤗
Thank you so much for this amazing video i am from ksa I well give you fallow
Thanks very much! Thanks for your follow too.
youaremyreasonforliving
Thanks! Really helpful
You're welcome!
What about mixing an excess of weak acid with a strong base?
hiya, just wondering you can also make acidic buffer from weak acid and strong base. How does this work?x thanks in advance for any help :)
This video was extremely helpful to me, thank you sir and continue making videos
Thanks! Please share the vid.
Is it not Possible to write the Two equations as one?
7 year aniversary of this video tomorrow
Thank you for the video, however I don’t get why the solution has to be a buffer solution in the situation where e.g OH- is added to an acidic buffer, cause the conjugate base from the salt doesn’t play a role in the reaction in resisting the change in pH
Hi, why does sodium ethanoate break up readily?
Am I correct in saying when you add an X-moles of acid to an acidic buffer, the moles of acid increase by X and the moles of salt decrease by X? ( And vice versa for adding an alkali to an acid) And then those new mole values are what you use for Ka calculations? Thank you :)
12:00 i dont get whats being opposed. surely if OH- reacts with NH4+ then you are reducing the concentration of NH4+ so i would assume the equilibrium shifts right to make more of the NH4+ thats been used up by reacting with OH-?
A buffer solution means resisting change in Ph right? So when an acid(H+) is added to that solution, the H+ reacts with the COO- and produces a higher concentration of COOH? Doesn't this mean the value of Ph decreases?
+Aashish_Menon Yes that's right. But remember pH is a measure of H+ ions. COOH dissociates weakly and hence does not produce many H+ ions. For this reason the pH value doesn't go lower. Hope this helps?
+Allery Chemistry Hi, I'm really confused about a certain part in the acidic buffer section. How come CH3COO-NA+ dissociates completely? I thought that for an acidic buffer, the salt has to be weak as well?
+Lilith Salts dissociate fully. The salt doesn't have to be weak only the acid has to be weak. Buffers don't work with strong acids.
Thank you!
such a cutie
What exam board do you base your videos on?
+Rida Arain They are generic and will apply to all boards.
Don't the salts (CH3COO-Na+) dissociate completely? WHy are they represented by an equilibrium in your video? Great explanations btw! Thank you!
Yes this is an assumption that is made, not quite reality. That is why the equilibrium arrow is included.
Why are the concentrations of the salts low ?
Why must we add the salt of ammonia to the buffer?
+Zift™ All buffers are made from a weak acid/base and its salt. So in this case you are talking about making a basic buffer.