- In this video,we're going to it is in talking about conjugate acid-base pairs. We're going to introduce the idea the a conjugate acid-base pair using an example reaction. The example reaction isbetween hydrogen fluoride, or HF, and water. So hydrogen fluoride is a weak acid, and also when you placed it in water, it will certainly dissociate partially. So several of the HF will certainly dissociate, and also you'll get fluoride minus ions. And then that dissociated H to add ion. Therefore this dissociated H plus ion will get donated come our water. So water then becomesH3O plus, or hydronium. And so this process isin dynamic equilibrium, reason it deserve to go forward,and it deserve to go backward, and eventually, those two prices are equal, and also they're both happeningat the exact same time. For this reason in this reaction, us havea couple things walking on, and we're gonna think about it in terms of hydrogen ions being exchanged. So if we simply look atthe hydrofluoric acid, and also we watch in the front direction, ours HF is ending up being F minus. And it's doing the by donating or losing, for this reason I'll put a minus for losing a proton. So our HF loses a proton that forms our F minus or fluoride ion. And also then we have the right to look at that same procedure happening in the backwards reaction. Therefore if us look in ~ the backwards reaction, i m sorry is also happening, the fluoride ion can pick increase or expropriate a proton from somewhere. Therefore it have the right to pick increase an H plus, so I'll have actually a plus, H add to here. And so when fluoride accepts a proton, us reform our HF. So we can see that HF and F minus have actually this special partnership where friend can form one or the various other by shedding or acquiring a proton. And also we have the right to see a comparable relationship in between water and hydronium. So, water here, we stated water is accepting a proton native HF, therefore we view that water will get a proton, and also that will offer us hydronium. In the reverse reaction, hydronium have the right to lose aproton to revolutionary water. So, minus H plus. So again we have these 2 species, water and hydronium, the are regarded each various other by having, or not having, one H plus. So in chemistry, we speak to these types that are associated in this method conjugate acid-base pairs. For this reason the main definition, or my official definition ofa conjugate acid-base pair is once you have actually two speciesthat are regarded each other. Let's see, two varieties thatare regarded each other, related by one H plus. In this case, we have actually HF and also F minus the are concerned eachother by the one H plus. And so HF and also F minus area conjugate acid-base pair. We likewise have water and hydronium, i m sorry are likewise related by that one H plus. So water and H3O plus are alsoa conjugate acid-base pair. You can probably tell native the name, but whenever you have actually aconjugate acid-base pair, one point in the pair will be an acid, and the other thing will always be a base. The an interpretation of i beg your pardon one is the acid and also which one is the base comes from the Bronsted-Lowry meaning of acids and bases. For this reason the Brondsted-Lowry an interpretation says something that can donate an H plus, therefore anything that will certainly giveaway an H to add is one acid. Therefore we can see that, in this case, ours hydrofluoric acidis acting as the mountain in the conjugate acid-base pair. And also that way that fluoride needs to be acting as the base. And also that provides sense, since the Bronsted-Lowry an interpretation of a basic is other that will certainly accept an H plus. And also that's precisely what it does in the reverse reaction. Your F minus will pick increase an H plus and also go ago to her acid. So we can also look at water and H3O plus. For this reason here, water is gaininga proton, or accepting it, so water is acting as a base. And in the turning back reaction, H3O to add is donating a proton, so H3O add to is acting together an acid. The connection betweenconjugate acid-base pairs we deserve to write a small bit more generally. So, if us representany generic acid as HA. For this reason this is our acid. We stated that a mountain issomething the donates a proton. For this reason it'll lose the proton, and when the does that, itwill kind the conjugate base, i beg your pardon is represented by A minus. In the turning back reaction,our base, A minus, can acquire a proton and also remake our acid, or conjugate acid. For this reason whenever you have two types that have basically the exact same formula, which we abbreviated below as A minus, other than for one has actually anH plus and also one doesn't, then you recognize you have actually aconjugate acid-base pair. For this reason let's look in ~ some an ext examples of conjugate acid-base pairs. We experienced above, HF, or hydrofluoric acid, it's conjugate base is F minus. So here HF is our acid, andwhen that loses the proton, we space left with F minus. We observed in the very same reactionthat water deserve to act together a base. For this reason if water is our A minus, if the water accepts a proton, it develops the conjugate acid H3O plus. For this reason the instance we've gone v so far, HF, is for a weak acid. Yet we can additionally talk about the conjugate basic of a solid acid, choose hydrochloric acid. HCl is a strong acid, therefore that means it totally dissociates. For this reason it gives away all of its protons, and when the does that, we're left with theconjugate base, chloride. So also though chlorideisn't an especially basic, it's quiet the conjugate base of HCl. And also last however not least, we're gonna go through two instances where the looks favor we could havea conjugate acid-base pair, yet we actually don't. Therefore one instance is, whatabout the relationship between H3O plus and OH minus? If we think of our acid up right here being H3O plus, if we lose one proton, we experienced that that conjugate basic is water. If water loses anotherproton, we obtain OH minus. So the distinction betweenthese two varieties here is 2 protons instead of one proton. So these two, hydronium and also hydroxide space not a conjugate acid-base pair due to the fact that they different by twoprotons rather of one. And also then the lastexample we'll look at is, we claimed that fluoride isa conjugate base of HF. Therefore what about the relationship between sodium fluoride and fluoride? and also so these two room alsonot a conjugate basic pair since if us take our fluoride ion, and it accepts a proton, us don't gain sodium fluoride. Lock are associated by a sodium ion. For this reason by definition, this two are not a conjugate acid-base pair.
So in this video, we learnedthat a conjugate acid-base pair is once you have two varieties and they have the exact same formula, except one has actually an extra proton. So the acid has an extra proton, i m sorry it have the right to lose to kind the base.