 Okay, morning everyone. Good morning everyone who made it today. Looks a little light today. I think some of the online people are taking it today though. So yeah, so the test is in the testing center. If you're an online student, it's there for you to go take. So and for everyone else, it's on Friday. So make sure you're studying chapter six through nine and the practice exams, practice quizzes, practice quiz and all that. Okay, so let's settle down and get started here. Let's finish up chapter nine. So the stuff that won't be on the test is this buffer, buffer's topic. Okay, so let's learn about buffers. Buffers are solutions. Well we did a lab on buffers already, right? And you guys hopefully remember that the unbuffered solution was able to change pH much greater range than the buffered solution is. Okay, well that's really the definition of a buffer. A buffer is a solution that has the ability to resist changing pH when acids or protons are added or bases or hydroxide ions are added. Okay, so you've got a solution that will counteract that change and the reason is through Le Chatelier's principle. Okay, so yeah Le Chatelier's principle. So many useful buffers consist of a solution containing a mixture of a weak acid and the salt of that acid, so we call that a weak base. Okay, so let's look at this one in particular. So this is acetic acid. In fact this is this is like vinegar. Here vinegar is actually a buffer. When you have acetic acid in solution what you'll find is that it will actually be in solution with what we call its conjugate base. You guys remember conjugate acid, conjugate base, right? So remember if we did this, well let's let's do it this way just to emphasize the reaction mechanism. Okay, so remember when we're talking about pH, pH will only correspond to a change in the concentration of H+, right? So that's what we're really referring to when we're talking about pH. Also OH- will eat up H pluses to make water. Okay, so those will also change the pH. In fact when we add these protons this will lower the pH, lower it, lower it, lower it. So if you have a really low pH that means it's very acidic, right? And these things here if we add those, those will raise the pH. Okay, so this would be like pH of 1, that's super acidic. This would be like pH of 14, that's super basic. Okay, so remember it only corresponds, it will only correspond to the change in this or in this, right? Or consequently this because this, these two things are essentially equivalent, right? Okay, so what happens in this reaction mechanism? So let's just draw this structure really quick, just draw the Lewis structure. Okay, so when we add water to this, or when we add a base to this I guess I should say, let's see what happens to this solution if we add a base to it. Okay, so a base would be like a hydroxide ion. So normally what should happen when we have a hydroxide ion adding to a solution? That's going to increase the pH, right? But that only increases the pH because the hydroxide ion is actually present in solution, okay? So what happens if we add hydroxide to a buffered solution? The lone pair electrons will come over here and grab the proton off of the conjugate acid and push the reaction this way to form, to form the conjugate base and water, okay? So what you see here is that hydroxide is no longer present in solution, right? Because the hydroxide reacted with this acid here to make the conjugate base of that acid and water. Okay, so there's no more hydroxide in solution. Since hydroxide is the only thing that could have changed the pH in our equation down here, right? And we've used it up. That'll allow the buffer solution to stay at the same pH. Let's look at the, a similar equation, a similar reaction mechanism. But instead of starting with the conjugate acid, we'll start with the conjugate base here, right? This part. So that's the conjugate base, right? So if we add protons to this or hydronium ions, if you will, like that, what's this thing going to do? It's going to remove the proton from that hydronium ion, thus effectively canceling out the pH change that that would have occurred or made occur, right? So this, one of these things will drop the pH. But if we get rid of it, it won't drop the pH anymore, okay? Does this make sense? No? Okay, so this would be like, here, let's, so, okay, let's, let's just ask, for those of you who say it doesn't make sense, why doesn't it make sense? What doesn't make sense to you? Well, whoever said no, who said no? Somebody did, right? Why doesn't it make sense to you? So remember, okay, so, okay, so remember, so remember, let's just think about this, okay? Let's just think, right? If we have this in solution, right? This will raise the pH, okay? Are we cool with that? Is everybody cool with that? Okay, so let's look at this equation here, right, down here. So we had it in solution to begin with, right? So it should normally raise the pH. Is that cool? So we're okay there, right? But what happens? It gets taken out of solution because it reacts, right? And now it's not in solution anymore, right? There's nothing, no OH-minus is there. Do you see that? So if there's no OH-minus is, can they be raising the pH if they're not there, right? No, it's not, the pH will stay the same. Remember the lab that we did when we compared the buffered to non-buffered solutions? Why did the buffered solutions not have the pH change, the dramatic pH change that the unbuffered solutions did? It's because these things were getting taken out of the equation to be forming water here. Same thing here, right? If this thing's the only thing that can lower our pH, right? And we take it out of solution, then it can't lower the pH anymore. This thing doesn't do it, right? Does this lower pH? No? No. It doesn't do anything to it. Not OH-minus though, okay? OH-minus. So hydroxide ions, okay? You only think there's an OH in it because I drew it out, right? This other thing, see, when I drew it like this, you didn't think there was an OH in that, right? Okay, so don't necessarily think that just because it's got, well, we're gonna learn about organic chemistry in like two seconds, okay? And when the thing is OH by itself, that's the only thing that's going to lower the pH, or raise the pH, pardon me, OH-minuses. Okay, so does this clear now? Is it clear? What about to everybody else? Good? Good? Good? Do you understand? Okay, good. So this is essentially the way a buffer works. It's gonna push the reaction back or forth, right? Depending on what you add to it. So you can see here, this is CH3COOH, right? That's that thing that I have on the bottom there, over there on the board. If we add OH to this, so all of these things are present in solution, this one and this one, okay? If we add OH to this solution, what will happen? OH will remove that proton there and make this, and water, right? If we add acid to this solution, what will happen? This thing here, just like what we have on the top there, will be taking the proton away from the acid and going back to this thing here. So it's like Le Chatelier's principle, going back and forth, back and forth, back and forth, okay? This is why you can keep adding acid-base, acid-base, acid-base to these buffers and they won't change the pH. It's like your blood, your blood is a buffer. That's why we can breathe in oxygen, breathe out carbon dioxide without changing the pH of our blood too much. And in fact, if you do end up changing the pH of your blood by one pH point, it's like instantaneous death. So buffers, buffers, yeah, buffers are very important in physiological, so they have physiological consequences. They're important in industry, they're important in everything, okay? And this is the principle by the way all of them work, because you've got a mixture of both the conjugate acid and the conjugate base of a weak acid, okay? So you can see here, this is breaking it down, just like I did here, except I showed it in more detail. You see, any acid reacts with the anions of the salt, right? So the H plus is reacting with that to form this, so there's no more acid present, right? And any base will react with the acid, right? So if we look over here, there's no base in there anymore, no OH minus. You guys see that? See it? See it? Look up there. See it? Thank you. Okay, equilibrium is established between acid and salt and buffer is Le Chatelier's principle in action. Okay, so you can see here, remember the change in color, so this is some indicator. So this is an indicator showing pH 7, so the left solution is not buffered. The right one is, universal indicator has been added to each solution. We add base to this, the unbuffered solution and the buffered solution will look what happens, right? The universal indicator changes color, right? Because the pH has changed, okay? This one, the pH hasn't changed, even though we added the same amount of sodium hydroxide to it. Okay, same thing happens here except opposite, right? Here we have acid being added to this buffer, our non-buffered solution and acid being added to the buffered solution. Notice this stays at the same pH. This goes down in pH, okay? Clearly indicated by the universal indicator there. Okay, so just like you guys were all wondering, how could I figure out the pH if I have both the pKa of this weak acid and I know the concentration of base and acid that I added to this thing or, sorry, the concentration of the conjugate base and the conjugate acid that I have of this weak acid? Well, you can do that using this equation, the Henderson-Hasselbach equation, okay? So the pH equals the pKa of the weak acid. Remember, pKa is the negative log of the kA, so we talked about that last time. And then it's going to be just plus the log of the concentration of conjugate base over conjugate acid here. So that'll tell you what the pH of your buffer solution is, no matter what concentration of these conjugate acid to conjugate base you have. So again, just to go over again, adding a basic substance to a buffer causes changes. The OH will react with the H3O+, producing water. Acid in the buffer system will replace the H3O+, consumed by the base. The net result is to maintain the pH. Okay, so again, Le Chatelier's principle going back and forth, back and forth. It's just the opposite here. It just talks about what happens when it's added, an acid is added to the solution instead of a base. And it's going to just go the opposite way. The conjugate base will mop that up. Okay, and last thing we'll talk about today is buffer capacity. So we say a buffer has a certain capacity and that capacity is to resist pH change. So it's a measure of the ability of a solution to resist large changes in pH when a strong acid or strong base is added. So you can imagine potentially that different buffer systems have different abilities to mop up acid or base. Okay, that's known as the buffer capacity. So it can be also described as the amount of acid or base that's able to be absorbed by a buffer without causing a significant pH change. Okay, so that stuff won't be on the test on Friday but we will be responsible for it for the final. Are there any questions? No? No questions. Just think. Almost done with the class, guys. Isn't that awesome? I'm excited about it. Okay, so let's move on to organic chemistry, which is really awesome for me because I'm an organic chemist by trade. So all of my research has been done in the field of organic chemistry. So all of this stuff that we've been talking about previous to this is kind of not as interesting to me as organic chemistry. The cool thing about organic is not only can you synthesize things from other things using the principles of organic chemistry so you can actually become like a molecular architect, right? Building molecules from smaller components. But you also don't have to use a lot of math. So this so that's probably good for everybody out there is that it's just looking at structures and not thinking really a lot about the mathematics behind the stuff. Okay, so all of this stuff previously is in the realm that all the stuff that we've been talking about previously is in the realm of what we call inorganic chemistry. Okay, and we'll get to the definitions of why something's called organic and why something's called inorganic. But on the surface you probably have some sort of idea as to why that would be just by knowing those terms. Okay, so the other thing about organic, the organic chapters in this book is I think there's like six or seven of them or five or six or something. And I think that they go into way too much detail for you guys. You know, I just think that there's too much stuff in there for you guys to know. So what we're going to do is do kind of a brief survey of these chapters picking out little pieces of the stuff that I think will be important for you guys to know going into the allied health fields. Okay, so that being said, even though there's like five or six chapters, we're not doing all of the stuff in all of the chapters. We're only picking little pieces. So don't let it become too daunting of a task for you guys or think about, don't let you guys think about it being too daunting. Okay, so let's talk about organic chemistry and synthesizing organic compounds. Okay, so we use organic chemistry all the time. We synthesize organic compounds all the time unwittingly. We're doing that right now as we speak. We're using those organic compounds to maybe think about what your professor's saying or text message your best friend in another class right now who's also bored or you know, anything you can think of. See the light that's shining on your eyes right now. Okay, so all of these things are, all these things are being allowed, all these processes are being allowed to happen because you are like a vessel of organic molecules. Okay, and these organic molecules, they have such a wide variety of structures and properties that they can do all of these strange and unbelievable things that the human body can do. I mean, you can think of all of the things that we can do. It's very amazing, you know, and it's all due to these little pieces of us, you know, so we could, I don't know, talk or we can walk or we can anything, you know, but they're all so different, right? So they're all going to take different kinds of structures and different kinds of molecules. Okay, so let's just talk today about, a little bit about the history of organic chemistry. Okay, so it's, the history of organic chemistry, just like the history of anything, is deeply, anything in chemistry is deeply rooted in the history of philosophy. Okay, because of course, people realize that things were happening somewhat on a chemical basis, you know, but weren't able to put down any hard and fast scientific laws and rules for a very long time. You can imagine the ancient Greeks didn't have, you know, the ability to analyze chemical reactions very well. But they did have ideas about where everything came from, okay? And the theory that we're going to talk about first, you can compare this to what we talked about in chapter two, but there is this guy, Aristotle, that you guys might have heard of before and we talked about him before. But he and some other ancient Greeks came up with this theory of vitalism. And this theory states, not only, but in relation to chemistry, that molecules that are found in living sources are unable to be synthesized, like synthetically, right, through synthetic means due to their inherent exclusiveness. Okay, so what does this mean? This means that, of course, they believed in a higher power or something, right? And they felt that this higher power gave these particular substances some sort of vital ability that would allow them to construct living organisms, okay? So this ability was only being able to be put down by some sort of a higher power. That humans couldn't inherently do this because they don't have that vital nature in them, right? So, like I said, this theory was established by Aristotle and wasn't discredited formally until 1828 by a guy who, when he discredited, didn't realize he was discrediting it, and I don't think he was, it was his goal to do this, okay? But anyways, we'll talk about him in a second. But this gave rise to two distinct categories of molecules, if you will. Molecules that were then known as organic molecules and other molecules that were known as inorganic molecules, okay? So organic compounds would be these that were derived from living or once living organisms. It's still a kind of similar term, but not really today. And inorganic molecules or compounds are derived from things that were never living, okay? Like the earth and the rocks and stuff like that. Okay, so these were the old definitions of these terms, okay? They're not the modern definition due to the fact that this vitalism was discredited, okay? So, there was this guy, Frederick Woller, in 1828, he accidentally, he was trying to synthesize a compound, an organic compound, because of course he was under the impression that it was impossible to synthesize organic compounds, because he didn't have a vital force, you know, that he could put down on these molecules to make them come alive, you know? So, he was trying to synthesize a previously unsynthesizable inorganic compound, okay? That inorganic compound was called ammonium cyanate, here. This is what he was trying to synthesize. So he started with lead cyanate, added ammonia to it in a water solution, and it briefly made it, although it made it in his reaction flask, and he couldn't see it, because in 1828 they didn't have advanced means of spectroscopy to actually be looking at every intermediate that was happening. So what you could only think of is, say, this is what was in the reaction mixture to start with, this was what was in the reaction mixture to end with, okay? They couldn't do, find these intermediates, because they were only there for a picosecond or something like that, okay? So, he synthesized an organic compound, which happened to be urea from an inorganic source. It was probably a good thing for him that it was urea, because it was so distinctive of a compound that he knew immediately what he had synthesized, right? He had a lot of familiarity, if you will, with this compound, right? As you can, as we probably all do, right? And could all imagine if you found it, you would know exactly what you had done, right? So, he stated to a friend of his, I can synthesize urea without the use of kidney from man or dog, okay? So, this, of course, put the scientific community on its head, right? Because now, either Frederick Woller was some kind of, you know, deity or something like that, or their whole concept of organic, inorganic vitalism had to come to an end. Okay? And, of course, Frederick Woller wasn't anybody any more special than any one of us, you know? He just did happen to do this reaction. That's the compound he actually synthesized. That's what urea looks like, of course, without its lone pair electrons. But this one synthesis discredited the vitalism theory. And this guy, Joseph Rosilius, who was one of the leading scientists, leading chemists of his day, stated that this was the great tragedy of science. I think somewhat tongue-in-cheeky was saying this, is that the slaying of a beautiful hypothesis is able to be done by the presentation of an ugly fact. And the ugly fact, of course, was that, you know, we could produce something that was from a living source without having it, without having some sort of vital nature to our synthesis. Okay? So, because of all of that, everybody thought, well, so these organic compounds were off limits for everyone. So they didn't even try to do them because they thought about, they thought that vitalism actually was occurring. So once Frederick Waller was able to demonstrate time and time again that he was able to synthesize urea, then other people started to synthesize more and more compounds that they were finding within different types of plants, animals, so on and so forth. Okay? So this really led to, like, a windfall in the expansion, if you will, of the knowledge of organic chemistry. Okay? So people just started synthesizing, synthesizing, synthesizing. And in fact, they started synthesizing things that were very similar to things that were coming from, like, plants or animal sources, but weren't exactly the same. Or they were extracting things from plant and animal sources and synthesize, or taking those compounds and adding stuff to them. Okay? Making them a little bit different. Okay? Like, putting a group here on them, taking a group here off. Okay? So the term organic chemistry really started to, you know, encompass all of this type of stuff. Okay? So all of this, all the stuff that was made endogenously through plants and animals, things that were now made synthetically through human interaction through, and also these additions and derivations of these compounds that they had synthesized, were all collectively put into a group. Okay? And that group is now known as organic chemistry, or organic molecules. So the modern definition of organic chemistry has nothing really to do with coming from living sources. Okay? It really means it's the study of carbon containing compounds, except elemental carbon. Elemental carbon, that's just just carbon, right? Like, soot, or diamond. Okay? And in organic chemistry is going to be the study of non-carbon containing molecules. Okay? So carbon, what we found, what we found is that carbon is an integral structure of all of these molecules. Okay? So organic chemistry has expanded to, or contracted if you will, to instead of look at the entirety of the periodic cycle, only focus really on one element. Okay? Inorganic chemistry would be the rest of everything else. Okay? So you might think that, well, since we're focusing so much on just this one element, that the amount of, I don't know, chemistry that we could actually think of to do is going to be more and more and more limited relative to the amount of chemistry we could do in the inorganic realm. Right? But fortunately for myself and other organic chemists, that's not the case. Because what you find is that there is an infinite number of organic molecules that can be made due to the bonding nature of carbon. Okay? And that's what we're going to be talking about for most of the rest of the term. It's carbon, it's bonding, it's nature of bonds, and the ability to synthesize these wide varieties in diverse structures, diverse, interesting, and unique structures. So what we find is that even though we did focus our thing, our definition back down to carbon instead of this kind of organic like you would normally think of that term to mean, what you find is that even so, the principal components of food, fuels, wood, clothing, they're all organic compounds, dyes, almost anything we're like wearing right now, anything we put in our bodies, anything we remove from our bodies, you know, everything is organic compounds. Okay? So here I'll let you look at this on your own, but this is typical properties of organic versus inorganic compounds. Of course, organic compounds are almost always covalently bonded together. Okay? Because of course, they're all going to be carbon bonding to carbon bonding to carbon or nitrogen or oxygen or hydrogen, those are all going to be covalent bonds. Okay? We know all about covalent bonds by now. Inorganics are often ionic compounds, just like you would imagine salts, things coming from the earth, that's where you get all your salts and you're going to have so group, are these groups over here bonding with things from these groups over here? The forces between the molecules, of course, for covalently bonded molecules, you already know that their intermolecular forces are very weak. Okay? The intermolecular forces for ionic compounds are very strong. How can we tell that? Well, what's the boiling point of a typical organic compound? I don't know. Let me think of one, ethanol or gasoline, right? Something like that. Gasoline that you put in your car is organic stuff. Okay? Very low boiling points relative to like sodium chloride, for example, right? Sodium chloride has a very high boiling point, like 900 degrees celsius. You can look at these other on your own. Okay, so remember the bonding pattern in carbon. The bonding pattern in carbon, we look at its electrons, right? So if we're looking at carbon here, it's got one, two electrons in the 1S orbital, one, two electrons in the 2S orbital, and one, two electrons in its, in two of its 2P orbitals, right? Because those electrons will follow Hans' rule jumping in from one orbital to the other. Okay? So just like what's shown here. And remember the energy level increases as you go up the periodic table. What you find is that carbon doesn't like to use its electrons when it's bonding in this sort of a fashion, okay? It can decrease its overall energetics by taking these three orbitals here, or if these four orbitals, pardon me, the three 2P orbitals and the one 2S orbital and taking them all and putting them together and mixing them up. So it's like throwing them in a blender and mixing them up, okay? So what it does is it takes these four orbitals, puts them in its blender called hybridization here, and then that blender spits out four new orbitals. So as many orbitals as you put in, you get out, okay? So we got one, two, three, four, one, two, three, four, okay? What hybridization does is allow the expansion of these electrons to be in their own sub-shell or their own orbital, pardon me, okay? So now we can see if we looked at a carbon here, right? If we were going to bond that with like a hydrogen, for example, right? We would only be able to make two bonds because there's only two empty or half empty orbitals, okay? Remember, you've got to put an electron from one atom and an electron from another atom in the same orbital to make a covalent bond, okay? So instead of doing that and only being able to make two bonds, what carbon does is mix it all up and gets four orbitals out of there, and now carbon can make four bonds, okay? That lends itself to the tetrahedral nature of carbon, all right? So instead of only being able to make two bonds, carbon can make four bonds, okay? Carbon's that middle atom. So hopefully everybody remembers what carbon containing compounds look like. They have this 109 degree bond angle, all of that stuff, okay? So what we call this is hybridization, these new orbitals, hybrid orbitals, and we call them specifically SP3 orbitals. Why is that? Because they were derived from one S orbital and three P orbitals, okay? So we call it SP3. So in fact, we have four SP3 orbitals, okay? So does everybody see this and kind of get this, okay? So again, if we were only having these two P orbitals that the electrons could bond into, we would have essentially a molecule that's going to be linear, okay? But in actuality, what happens is when we make these four SP3 orbitals, they want to get as far away from each other as possible, and as far away from each other as possible is 109 degrees, okay? So it actually, instead of keeps them on this plane or on this axis here, it kind of rotates them a little bit to be on the edges of a tetrahedron, like that molecule that I'm showing you being passed around, okay? So you can look at this on your own time. There's your bond angle. So here's a couple of representations. This would be like the structure showing the structural formula. This is the Lewis structure, and this is what we call a space-filling model. This is what the actual molecule looks like if we were to be like a little person and be able to look at it. It doesn't look like that skeleton structure there. That's emphasizing the bonds and not the atoms, okay? This one is emphasizing the atoms and not the bonds, and in fact, this is what it really looks like, okay? It's like a little blob, okay? So, of course, carbon is going to be able to bond to other carbon atoms. This is how we get bigger and bigger and bigger organic molecules, and in fact, there's no limit to the number of carbon atoms that can bond to other carbon atoms. And that's why we inherently have an infinite number of organic molecules that can be made, okay? So you can see this molecule here. This is propane, like Hank Hill or something, right? Yeah, that's what it is, though. So you can see the tetrahedral nature, hopefully, of that carbon, and then you can see it here, too, on that carbon, and then you can see it here on this carbon, okay? That's how carbons bond together. If they only bond single bonds, okay? We're going to get into more complicated structures in a little bit, but good to think about these very simple structures first, okay? So, again, yeah, they can bond a lot of different carbon atoms. Okay, so you can imagine that you've got two molecules that now have, here, let me draw these two molecules up here, now have the same atoms in them, but they're bonded differently, like diethyl ether and ethanol. So let's just draw the Lewis structures really quick. So this is ethanol, that's the stuff in vodka or whatever, and this is dimethyl ether. So if you look at the, if you put, if you drew, or if you figured out what the molecular formula of these two molecules are, you would find that they're the same, right? C2H123456O, right? So C2H6 O, C2H6O. But what you find is if I drank this stuff, right, I'd get kind of tipsy or whatever, but if I drank this stuff, I'd get dead, okay? So, like, there is a difference, okay? So things that are, have the same molecular formula, but different structures or different arrangements of atoms, we call those isomers, okay? So these things are isomers of each other. In fact, they're structural isomers. There's different types of isomers. Structural isomers actually have different bonding patterns. We'll learn about stereo isomers in a little bit, our later. Well, we did a whole lab on stereo isomers, actually, okay? The last thing I'm going to do is introduce you to functional groups. So most of the things we've been showing before now have only Cs and Hs in them, but as you can see by these two molecules that I've drawn up on the board here, they also have O's in them, okay? So what we call things that aren't carbon and aren't hydrogen in organic molecules, we call those functional groups, okay? So in this case, we have the functional group of an alcohol. An alcohol is something that's C, O, H, like that. With this C being bonded to three other things, that's an alcohol. When you got an O instead of bonding to an H, you got it bonded to two Cs, that's called an ether. That's why this is called dimethyl ether and that's called ethyl alcohol, okay? So we'll go over all the rest of the functional groups on Monday, or not Monday, I guess, Monday after Thanksgiving. So good luck on the test guys and I'll see you on Friday if you're coming here. Make sure you sign the sheet.