in this video I'm going to give you a nice simple explanation of how buffer solutions work so let's start with a beaker and this beaker contains a solution and this solution has got some universal indicator in it and it has a pH of around about seven it's neutral we take some acid as represented by some H+ particles that's our particle for an acid we add those H+ which represents adding an acid and unsurprisingly the solution would tarik and red color so universal indicator is indicating that we now have an acidic solution that makes sense we start with our same solution with some universal indicator in it turn green we take some alkali which is our Oh H minus we add that and unsurprisingly the color of the universal indicator would change and we would end up seeing that we have an alkaline solution however if we had a solution with a buffer in things are going to be very different and it's gonna behave a little bit strangely if we took some acid and I mean a little bit of acid not an enormous amount of acid just a little bit of acid we add a little bit of acid and that acid goods into the solution and nothing happens we could take some alkali add some alkali to the solution and again nothing happens this is the magic of buffering we've added an acid the pH hasn't really changed we add in an alkali the pH hasn't really changed that is the point of a buffer a buffer can maintain a solution roughly the same pH and resist the action of acids or alkalis that are added but it only works up to a point if you added an enormous amount of acid or an enormous amount of alkali it wouldn't keep working and the question now is what is going on here how is it possible that you can add acid or you can add alkali and not be changing the pH that is very strange and it actually turns out there is two things going on here one of the things deals with the acid and one of the things deals with the alkali so you actually have two main ingredients in a buffer solution and we'll look at what each one is and how each one works so we have our solution here one of the two of our buffer solution is going to be a thing called a che and the question is what is a che what is this key component and it turns out that a che is simply the name of a weak acid so any weak acid can be represented by H a where H is obviously hydrogen which is a key part of an acid because you need to have H phos particles and a simply represents whatever else you need to add to H to complete your weak acid so it could be an acid-like ethanoic acid or it could be a wide range of other weak acids a benzoic so H a is just how we're going to represent any weak acid and that is one of the two ingredients of a buffer solution so we have an equilibrium going on here so we have a weak acid will dissociate and it will produce H+ and it will produce a minus this is splitting up a minus is what we call a conjugate base the equilibrium however isn't a fair equilibrium it's not half and half the equilibrium is very very much towards left hand side because this is a weak acid weak acids partially dissociate so most of the H a is going to be undissociated and you're only going to get very very few H plus and a minus the vast majority is going to stay as a chase that's why adding the weak acid isn't going to immediately turn your buffer solution to you know going completely red and being an acid in terms of pH so let's look at how this actually works in practice so we have our solution there that's buffered and we know that one of the components of a buffer solution is our weak acid H a so let's think about how would H a react if it was exposed to some alkali particle system Oh H well what happens is your weak acid reacts with your o H and produces water and your conjugate base a - now this is of course alkaline because Oh H - is your alkali particle but water and your conjugate base this is overall going to be neutral this isn't going to be alkaline so what when you add your base which is your h- or your alkali you add that there it's going to react with your H a which is your weak acid these to react and of course you get this produced so they react together and you end up with this this isn't going to change the ph of your solution very much are you going to end up with a pH that's virtually unchanged of course if you added an enormous amount an absolutely enormous amount of h- it would absolutely overwhelm the h a you would run out of h a and it would no longer be buffered so buffers only work up to a point this is how you deal with Oh H - or your alkaline what if we added an acid well this isn't gonna work we're going to need to add another ingredient so we've got some acid particles there we want to add these and obviously there has to be some sort of reaction that gets rid of these now we notice this equilibrium here which we've seen earlier this a - could of course react with this H+ but remember this is a weak acid so we're not going to get very many of these these are going to be gone very very quickly so simply having H a as the only ingredient in our buffer isn't going to work because the equilibrium is far too far on this side far too few of these the trick is to add a soluble salt of H a so for example we could have na a so whatever a is we could have sodium of that now we have this reaction here which is na a fully dissociated to any + and a - any of a is going to be a strong base so that's why I've showed it with this arrow showing that it fully dissociates because it fully dissociates we're gonna get loads of a - there's going to be loads of a - floating around so we've actually got loads of a - this is - this is plus unsurprisingly there's going to be a reaction between those so those two react and you end up making your H a again which is one of your ingredients of your buffer solution and the H a is of course a weak acid so it's going to only partially dissociate so it isn't going to have very much effect on the pH it's gonna have a little effect because you're gonna have some h+ produced but it's not gonna be a very big deal so a buffer can maintain the pH between very narrow values as long as you don't add enormous amount so you've seen our two components of a buffer solution are your weak acid and the salt of that weak acid so you now know how a buffer works I hope this video was really helpful to you and it's finally making some sense if this video did help you please comment below and let other people know that this video is helpful to them and if you liked it and subscribe that also encouraged me to make more videos and suggest that this is actually helpful and finally thank you very much for watching