 Chapter 7 notes up, got about 20 emails. Okay, so Chapter 7 is solutions and colloids. Oh, this is probably the most important chapter you guys will be learning in this class, because most of you guys want to be part of the medical profession, more than likely, right, lab sciences, or a lot of those kinds of things. And one of my former students actually, I was talking to her the other day, she asked me to relate a story to you guys, and some people think this is a cheesy story or made up or whatever, I don't know. But it really is a true story. And she was one of those people who thought chemistry was totally boned, why do you need this, blah, blah, blah, until this story was told, and of course when she got it in her head about this type of stuff, she really turned it around, of course. Even you guys who are doing poorly right now on the midterm, there's a lot that gets dropped in this class, and you can break your grade up quite significantly from the midterm to the final. So I don't think there's any reason to panic like many people, many of your classmates have already done, as you can see by the attendance today. The one thing that I, but she wanted me to tell you the story, and she made me promise to tell you guys, so I'll tell it again. Another one of the professors here, what was it, two terms ago, I think, told me this story, he was like, you've got to tell this story about how important chemistry is, and this guy, he's a biology guy, he doesn't really care about chemistry that much, because he doesn't use it on an everyday basis. But he told me the story about this medical doctor from Victoria. Maybe some of you guys have already heard this story from me. He told me the story about this medical doctor from Victoria, who he was personal friends with, who was an avid skier, and of course there's not much skiing around here. So he went to, I think it was like Colorado Springs, or something like some Colorado place, okay, so Denver or something like that, to go skiing. And what had happened was, of course, you know, he was skiing downhill, he got into some accident, and something minor, he had to go to the hospital, I think he broke like his leg or his foot or something like that, but he had to go to the hospital. And what they ended up doing, of course, he was a medical doctor, so he was curious in what they were doing to him, you know. And so the nurse gave him, you know, all this medication while he was kind of dogged up and, you know, wasn't really thinking about what was going on. And afterwards, when he was kind of coming to a little bit more, he asked the nurse to see his chart, you know. And what had happened was she gave him his chart, and he looked at it, and he said to the nurse, oh my God, I can't believe you just killed me, and then the next day he was dead. It was because this nurse had given him a mega dose of some drug, you know, that, of course, she just did a calculation wrong. It was like, instead of doing like, I don't know, one gram or something like that, you could imagine, she might have done like 10 grams or something like that, but that's not that much difference, right? Like if I were to ask you, you know, if the real answer was 1.0 grams, and you put 10 grams on your test, you might be very upset if I took off points for that or a lot of points for that. Of course, the exams aren't the main reason that you're in this class. The main reason that you're in this class is to be able to, you know, be able to give medical advice and, you know, be giving people solutions of drugs and things like that, you know, on a daily basis. And you guys really have to know about this stuff. So this guy, you know, I mean, it wasn't something, it wasn't something that she meant to do, you know, she's just some calculation error, and this guy was a doctor, he realized that he was going to die the next day and he did die, you know? So if you guys think this class is, like, hard or, you know, like, there's too much work or all of this stuff, it really is because it's very important to get the concentrations especially of the drug solutions right, you know? And if you don't do it, there are, you know, fatal circumstances for these things. In fact, I think what I'm going to do from now on for the quiz one instead of just getting to know you thing because, you know, I don't know how much good that really does. I think I'll start doing, like, a little section on this type of stuff because you can look on Google. I mean, I could look on Google right now and find instances of, you know, like, RNs going to jail because they, you know, overdosed patients and it's not that they overdosed them on purpose, they weren't malicious, they wanted to kill these people, you know? It's just because they did a calculation wrong, you know? It was like they were having a bad night, you know, it was really hectic in the ER or whatever, you know what I'm saying? And they just did a calculation wrong, you know? Yeah, so some of them are involuntary manslaughter, you know? I don't know what all the legal ease is, you know? But you can look up on the internet and find a lot of these things. People go to jail for, you know, years of their life because of this. Yeah, I mean, and that's probably the worst thing. You think about killing somebody, you know what I'm saying? So, again, you know, this class really, I mean, I'm not trying to inflate the importance of this class, you know, just because, you know, I think it's a great class or whatever, you know? But it really, this is the only time you will learn how to make solutions. This is the only time you will learn how to do these calculations. And if you really don't, if you take it with a grain of salt, you know, that's what you're going to get. It's the grain of salt out of it, you know? And I don't know. That's enough of that stuff, you know? But I just wanted to let you know, because I promised this person that I would tell you guys, and I know they're a good storyteller, you know? But hopefully I got the point across, you know? But anyway, so let's talk about solutions and colloids. And like I said, this may be one of the most important chapters in the book, if not the most important chapter for you guys who are going to be giving solutions to people on a daily basis if you pursue your intended career. Okay, so what is a solution? A solution is a homogenous mixture, just like we talked about. We talked about this in chapter one, solutions or homogenous mixtures at least, of two or more substances in which the components are present as atoms, molecules, or ions. Okay, so if you look around, I see many solutions in class like that Barks root beer right there. That's a solution. Probably what's in these cups is the solution. Even this stuff, this soap here is a solution. Okay, so there's a lot of solutions around. A solute is a substance in the mixture present in the lesser quantity. So what we had like, what we're looking at here, this sugar water solution. The water of course is present in the higher amount. There's more moles of water if you will, than there are of sugar. So what we call the sugar is the solute. That's the substance in the mixture that's present in the lesser quantity. The solvent of course, the solute is the substance in the larger quantity. So in this case, the solvent will be water. And remember, when you put sugar in water and mix it up, it all dissolves. You don't see the sugar anymore. But if you drank the water, you would taste that it was sweet. So the sugar is still present. So it's not like it disappears or there's a chemical reaction happening. Because the sugars taste the same, like if you put your finger in some solid sugar and eat it or drink the sugar water. It's more dilute in the sugar water because you're not taking as much at the same time. So an aqueous solution, you'll be hearing me refer to this quite a bit. This is a solution where water is the solvent. So you can see these pictures here. We can have a solution that's got a solute component that's a solid and the solvent is a liquid. We can have a solution where the solute component is a liquid and the solvent is a liquid. This is like, I don't know, 10 drops of alcohol. This is like Everclear or something like that here. Or, I don't know, Budweiser or whatever you like. So 10 drops of oil. Here you see here, right? This is a oil layer and now a water layer. This is a non-homogenous mixture. Huh? This is non-homogenous. You could call it heterogeneous. Yeah, it's the same thing, right? So solutions can be solids, liquids or gases. Air is probably the most common solution of gases that you guys know. Of course, oxygen, nitrogen, several trace gases are dissolved in the air medium, okay? The solvent, I guess, of air is nitrogen because that's present in the highest amount. So there's 78% nitrogen, 21% oxygen, and about 1% of all the other little components in there, argon, carbon dioxide, so on and so forth. Alloys are homogenous metal mixtures in the solid state, okay? So the way that you get an alloy like brass is to heat up the various components of the mixture. So when you get them into the molten state, you can mix them up and then they'll form a homogenous mixture when you cool it down. So that's the way you can get solid mixtures. So we'll focus on liquid solutions, of course, because of what you guys want to do in your chosen career. And because in the lab, we can do liquid solutions much easier. We can work with liquid solutions much easier than we can with solid or gaseous solutions. Okay, so let's talk about general physical properties of solutions. In solutions, particles are too small to reflect light. Okay, so that's why you don't see the actual particles floating around. You can imagine comparing this to a heterogeneous mixture of sand and water, and you mix that up, right? You can see the same particles flowing around within the water, okay? But when you mix up your sugar or your salt, it looks like they disappear, right? We call it dissolving, okay? But the reason is, is because they are too small to reflect light. So the solutions are transparent. The particles, of course, are in constant motion. You can tell this by, you can put electrodes in a solution and pass current through it, okay? They're not settled by the influence of gravity. So if you keep a solution over time, right, like that root viewer over time, it's not going to separate out. You won't have, like, clumpy stuff at the bottom and liquid stuff at the top, okay? So here is the chemical equation of the dissolution of sodium chloride. Okay, so you can imagine taking your salt shaker, putting a glass of water and putting some salt in it. This is the chemical equation for that, okay? Here's a few different examples of solutions. We've seen some of these in labs, so you can have clear solutions, purple solutions, yellow solutions. The only difference is that between solutions and what we call colloids is that in solutions you cannot see the particles, okay? So we have different types of solutions we can make. One, division that we can do in solutions are between electrolytes and non-electrolytes. So electrolytes are solutes that are soluble ionic compounds. So soluble ionic compounds, when dissolved, they conduct electricity, okay? This is why you don't throw, when you're taking a bath, you don't throw your hair dryer into the bathtub because it'll blow you out of the water because there's ions in your tap water, okay? That's why when you taste your tap water it tastes kind of, you know, calcium-y. Calcium-y, you know? So you've got calcium ions flowing around in there. You put electricity in there. With those ions, the electrons can jump from ion to ion to ion and, of course, conduct electricity, okay? That's how people die, okay? You can also have non-electrolytic solutions. This is covalent compounds. So these are ionic compounds that are dissolved, electrolytic solutions. Non-electrolytes are non-ionic compounds, okay? So a non-electrolyte, the most common one, especially we've been talking about it for a while today, would be like sugar. This would be a covalent compound that dissolves in water. Remember, water is very polar, so it can dissolve many, many things, okay? So we'll talk about the ability of water to dissolve it. So non-electrolytes are solutes that are soluble but do not dissociate, okay? So they don't conduct electricity. So electrolytes are ionic, non-electrolytes are covalent, okay? The volumes of solute and solute and solvent aren't additive. Don't worry too much about this one. I don't think I'll give you any problems about that. Okay, so what does it mean, solubility? How much of a particular solvent can be dissolved and a certain solute can be dissolved into a certain solvent at a specified temperature? Okay, so the factors which affect solubility, remember I told you, water's polar, so it's going to be able to dissolve things that, a lot of things, okay? In fact, it's going to be able to dissolve things that are also polar, okay? Why is that? Because the polarity of the solvent and solute must be the same in order to be able to have them dissolved in each other, okay? In fact, one of the things you may take with you from this class, hopefully, it's one of the things that most people remember is that this little phrase here, like dissolves light. So, if you've got something polar, it's like something else that's polar, okay, so they'll dissolve each other, okay? Non-polar things dissolve other non-polar things, okay? So, if I have fat, right? Fat is... Has anybody tried to mix oil and water before? Have you ever seen it happen? Have you ever gone to the grocery store and seen Italian dry-seeing or something like that? When it's sitting on the shelf, it's all separated, right? Why do you think that is? That, definitely, definitely. That's a good thing. So, which one has the higher density? The water has higher density, right? But why don't they dissolve in each other? Why doesn't the oil dissolve in the water? Oil must be what? Non-polar, right? It must be non-polar, but yeah, you're right, it does have lower density, too. So, that's a good insight. So, the more different they are, the lower the solubility. Temperature, has anybody ever made rock candy when you were a little kid or done something like that? Remember what you did to you? You put a bunch of sugar into that thing and there was so much sugar, right? And then you heated it up and all the sugar dissolved, right? And then when you cooled it down, the sugar started coming out of solution and make like little rocks on your little string, right? This is because temperature increases the solubility of solutes, okay? So you put all the sugar in there. It was too much to be dissolved at room temperature, so you heated it up to get it all dissolved, okay? This is a common practice in the chemistry life. Ironically enough, if you have gases in your solution, dissolved in your solution, so has anybody ever drank soda before? Yeah, right? So you open it up and you drink the first drink and it tastes really good. It's all like, I don't know, kind of spicy or whatever with the carbon dioxide, you know, the carbonation that's coming. But what if you leave it overnight, right? And then try to drink it the next day? Does it give you the same kind of feeling? Yeah, it's not even after an hour. Yeah, not even, right? Why is that? It's because the solution heated up and gases, actually, when you heat gases up, when you heat solutions with gases up, the gases don't like it, okay? So gases get dissolved in cold solutions like carbon dioxide in your soda and solids get dissolved in warm solutions like your rock candy, if you recall, okay? So here's a little graph of solubility. You can see some solids are weird. Don't worry so much about lifting solids. But you can see that increasing, increasing, increasing. This is a liquid here, glycine. This is like, what do you say, coolant, you know, in your car. So that's like that. So you can see if you've got solubility less than 0.1 grams per 100 grams of water, we call that new soluble, okay? Slightly soluble is 0.1 to 1. 1 to 10 is soluble. 1 greater than 10 is very soluble. And you can see in the degree of solubility of all of these compounds, as you probably can read them up here, that you can see sugar, there's 179.2 grams per 100 grams of water. So that's very soluble. So you want to compare this to these and you can see is this soluble, is this insoluble? And you can see here, again, look, all increasing in solubility as the temperature goes up, except for SO2, right? SO2 is a gas, so it decreases as the temperature goes up. In fact, it's insoluble in water at about 43 degrees Celsius. So again, a soluble substance is a substance that dissolves a significant extent in a solvent. An insoluble substance is very, very, very, very, very slightly soluble, okay? But we call it insoluble because it effectively doesn't dissolve anything. So when we're talking about solubility and water and ionic compounds, how does the water actually break apart these ionic compounds? Remember, you guys have seen the model of sodium chloride probably more times than you have liked to by now. But here it is again. So you can imagine this slide here showing us this block of sodium chloride and you see the little water particles. Remember they look like little boomerangs, okay? What they're doing is they're all taking a little ion away. Notice which side of the water molecule is associated with the ion that they're removing, okay? Remember, when we draw water, it's got a dipole moment, right? So that means it's got a partial negative here, partial positive here, right? So that's what is being shown in your little diagram here. You can see for the anions, the partial positive side of the water is next to it, right? For the cations, the partial negative side of the water is next to it. That's how they carry them away. And in fact, these water molecules form like kind of a, what we say, a coat, okay? A coat around the ions. And we call that ion with the coat on it. It's called a hydrated ion. So it'll have like a spherical layer of water molecules around the sphere of the ion. And you can see the undissolved solute is right here, okay? It just hasn't had enough time. Here you can see instead of an ionic compound, a covalent compound being dissolved into water, okay? This covalent compound has a dipole moment of itself. And of course, but it doesn't break apart, okay? Covalent molecules don't break apart like ionic molecules do, ionic compounds do. So the water molecules have to associate kind of like this, on one end or on the other end, as opposed to taking apart a particular ion. So a soluble not dissolved in a solvent is the forces between the soluble particles are too strong, okay? So if I have an insoluble ionic compound by putting it in water, the reason it won't dissolve is because the ions, they like to stick together more than water can pull them apart. So water's just not strong enough to pull them apart. They'd rather stick together. So yeah, this is what it's saying. The solvent particles are more strongly attracted to each other than they are to the solute particles. Okay, so how do we increase the rate of dissolution? You probably know this from practical experience. You could grind up the solute, right? Putting a big chunk of salt in water takes a lot longer to dissolve than just grinding it all up and making a lot of surface area. That's because, you know, if I have a big thing, a water molecule has to pick this one off before it can go to this one inside, okay? But if I crush it all up, right? Then there's just a lot of surface area. Or I could heat the solvent like we talked about. Or I could stir or agitate the solution. It'll get the water molecules moving around. So when we talk about liquid-liquid solutions, we talk about homogenous or heterogeneous mixtures, okay? So liquids that are not soluble in each other, we have a name for that. It's called immiscible. Okay, so water and oil are immiscible. These liquids don't mix together to form a solution. You can shake up like you're Italian dressing to get kind of a colloidal thing. Okay, colloid is something where you can see the particles inside of it. But you'll never have a solution. This is unlike things that are miscible, of course. They're always going to be dissolved in each other, like alcohol and water. So a good rule of thumb for solubility is light dissolves light, of course. Polar solvents dissolve polar or ionic solutes. Non-polar solvents dissolve non-polar or non-ionic solutes. So you can think of polar solvent being water, a non-polar solvent maybe being oil, okay? That might be a good one to say. Okay, so let's talk about concentration. So concentration is the amount of solute dissolved in a given amount of solution. We're going to be, to probably the chagrin of everybody in here, we're going to be using moles most often to be describing our concentration and solution. Okay, because it's the most common way to describe concentration. In fact, molarity is the most common way, and that's just moles of solvent per liter of solution, okay? So let's talk about concentration. Concentration of a solution has an effect both physically and chemically, right? Salt solutions are more dense than water, okay? So the solution has its own types of physical properties, right? Salt solution tastes different than water, pure water, right? A saltier salt solution tastes even saltier, right? So they have different physical properties. Sugar solution tastes sweet, okay, and is more dense. So the physical properties like the melting and boiling points are different, and the chemical properties of the solutions are different than that of the pure solvents. Okay, recall, chemical equations or reaction equations or dissolution equations represent a relative number of moles of reactants and products. So if I said we have, you know, 0.2 moles of sodium chloride that we're dissolving, you should be able to figure out that we would be getting 0.2 moles of sodium ions and 0.2 moles of chlorine ions due to this reaction equation, okay? It's very straightforward. It's showing you right there because they have a 1 to 1 to 1 ratio. We've already talked about this stuff. So many chemical reactions occur in solution, right? So the volume of solution is easily attainable where, blah, blah, blah. So let's just talk about this right here. Okay, so this is the equation that you're going to be needing to know. This capital M here, that's known as molarity. So this is the most common mole-based concentration unit. This is what all of those concentrations that you use are the solutions in chemistry lab. Okay, so like everybody who was doing the ion experiment that has already done it, when you looked at it, it said 0.1M, capital M. I'm sure you guys took note of it, right? Because you were wondering, what does that mean, right? If you didn't, you start should, okay? Because you make observations in lab, you want to know. That capital M means molarity, okay? So if we have 0.1M, what does that mean? We have 0.1M. So like most of the solutions were last night, 0.1M, I don't know, sodium chloride. What does that mean? That means we have 0.1 moles of sodium chloride. That's all that means. Can we figure out the number of grams we have per liter if we wanted to? Can we do that? Yeah, right? How would we do that? Use the molecular weight, yeah. Use the molecular weight or the molar mass, really. So here's some problems. Let's do a couple of these and we'll call them a day. So if 15 grams of sucrose were dissolved in 200 ml of solution, let's do it. So 15 grams, does that tell us how many moles we have? No. No, right? So we've got to change that to moles. So the number of moles of sucrose can equal 15.00 grams at the top. The molecular weight is 342.30, and the molar mass is 342.30 grams per mole. So that is, okay, cancel, cancel. Yeah, sucrose. And it says it's dissolved into 200 ml of solution. So molarity divided by what? One liter? What? Would it be one liter? One liter. No, it says it's dissolved into 200 ml, right? So what do we have to put here? What would you say we have to? 22 liters. 22 liters, or we could just do 200 ml, and then multiply that by 1,000 ml per one liter. So did everybody see how we did that? Is it pretty okay with that one? Okay, so let's try this one. This one. Well, number two is fairly easy. I'll let you do that one on your own. Number three, so number two, you just put the two numbers on top of each other. Number three, you put the two numbers on, you just do this part of it, right? Because you've got moles and mole weights. Number four is kind of like number one. So here, I'll let you do all three of those on your own. Okay, let's see if we can do it. Okay, yeah, we'll do this dilution factor before you guys leave, so you guys can start on your homework if you prefer. So if we wanted to dilute the solution, we can prepare a less concentrated solution from a more concentrated one, and if we know the volume and molarity of the initial solution, and we know the volume of the final solution, we can figure out the molarity of the final solution. Okay, so we can do it in accordance with this formula, which is very similar to the gas laws that you've learned last chapter. This is similar to Boyle's law. Okay, so Mi, that indicates the initial molarity, Vi indicates the initial volume, Mf indicates the final molarity, and Vf indicates the final volume. Okay, so if I had any three of these variables, I could find the fourth one. So let's just do this problem before we leave this one. So just calculate the molarity of the solution made by diluting 50 mls of 0.1 molar HDL to 1 liter. Okay, so what I would do is write like this, M1 equals what? What's the M1? Anybody can do that to me? 0.1, 0, right? Hold on. V1 or Vi is what? 50 milliliters. Okay, so it's important you give me that. Yeah, we don't know that one yet. And Vf, 1 liter, 1 point. So the very first thing we need to do is convert milliliters here to liters, okay? So multiply that by, range this equation to isolate the Mf variable. Right, so what do we need to do? We've got to get rid of this Vf on that side. So just say, divide both sides by Vf. Good job, yeah. Cancel and we get this new equation. Mf equals M1 V1 over Vf, okay? And then all we've got to do now is plug in our numbers here and we should get Mf, okay? So go ahead and work those types of problems out. Yeah, if anybody has any questions about anything, feel free to come talk to me during office hours, okay? Right now, yeah. And then after office hours, I'm going to be busting out grades. So you should have all, like I was saying, you should have, if you get the time machine coming down and signing, you should have all your grades by, I guess by Thursday, depending on how fast they get them.