And we've shown the movement of electrons using curved arrows. So this is the conjugateĬonjugate acid-base pairs. And on the left, acetone is functioning as a Bronsted-Lowry base. So on the right would be water, which is our conjugate base. And you take a proton away from that, and you're left with a conjugate base. H3O plus is functioning as our Bronsted-Lowry acid, right. So identifying our conjugateĪcid-base pairs again, on the left hydronium And then the electrons in blue here move off on to the oxygen to add another lone pair of electrons onto that oxygen, giving us water. Right here on the oxygen picked up this protonįorming this bond, right, so this bond right here, the So H2O, let me draw that in and show our lone pairs of electrons. The lone pair on the right of the oxygen picked up a proton, formedĪ bond, and so we get this with a plus one formalĬharge on the oxygen. So on the left, right, the lone pair on the left of the oxygenĭidn't do anything. So if acetone functions as our base, a lone pair of electrons on this oxygen could take this proton right here and leave these electronsīehind on this oxygen. Remember when you're drawingĪn acid-base mechanism, your curved arrows show It's going to donate a proton to acetone, which is going to be So the hydronium ion is gonna function as our Bronsted-Lowry acid. So on the left we have acetone and on the right we have Let's do one more acid-base mechanism for some extra practice here. These two electrons up here in magenta are the ones that are That's a very common mistake, because curved arrows show the See, and I'll do this in red so it'll remind you not to do it, is they show this proton right here moving to the hydroxide anion. All right, the biggest mistake that I see when students are drawingĪcid-base mechanisms is they mess up their curved arrows. So we've identified ourĬonjugate acid-base pairs. I'm writing conjugate base here, but it's really the conjugate acid, right. For hydroxide, hydroxide on the left side functioned as a base, right. Let me identify this asīeing the conjugate base. Just take away a proton, and this would be the conjugate base. What is the conjugate base to acetic acid? Well, that would be over here, right. And we can even identifyĬonjugate acid-based pairs here. In blue are right here, which gives the oxygen a So these electrons in blueĬome off onto the oxygen. To follow the electrons, the electrons in here, So let's say those twoĮlectrons in magenta are these two electrons, and this was the proton This lone pair right here on the hydroxide anion Let's follow our electrons along so the two electrons, right, So let me go ahead and draw water in here. You add an H plus to OH minus? You would get H2O or water. We'd also have a sodium cation here, so we could think about that. And then now this oxygen we have three lone pairs of electrons around it which gives this oxygen a So on the left we would have our carbon double bonded to our oxygen. The products, I should say, of this acid-based reaction. Only the proton, so these two electrons are left behind on this oxygen. On hydroxide, let's say, are the two that are going to grab the acidic proton on acetic acid. So when you're drawing the mechanism, you used curved arrows to And hydroxide is going to accept a proton. On the left, acetic acid is gonna function as our Bronsted-Lowry acid. ![]() Skill when you're doing organic chemistry mechanisms. Drawing acid-base reactions is really an important
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