 Okay, guys. Good morning. Recall. There it is. Well, I guess the first thing I want to say is, finishing, putting in the exam grades, exam two grades into the grade book, I was pleased with how much better you guys are doing on some of the stuff. So, I just wanted to let you know that I see that you guys are increasing the effort and increasing the knowledge, and it's really good, you know, and really cool. So, just keep up the good work. You should, we'll definitely be handing your exams back next period, probably sometime in between now and then you'll see your grade on Blackboard. Okay, so, that being said, let's continue to talk about Collegative Properties. So, we talked about boiling point elevation, and remember, the equation here is the change. Remember, whenever we see this triangle here, that triangle means the change of Tb, that indicates the boiling temperature. Kb here is one of these constants, so you can see the boiling point is listed next to its Kb. The melting point is listed next to its Kf here. And so that change in boiling point will be the Kb, which is one of these numbers, so I have to give you this list in order to do one of these problems, times the molality of the solution, and you can calculate that yourself. The freezing point depression, remember, is very similar to the expression for boiling point elevation. It's the change in the freezing temperature equals the freezing constant, which is here, given to us here on this table, times, again, the molality of the solution. Okay, so you're going to have to figure out the concentration of the solution in molality before you can do this. Okay, so here's a phase change diagram. We don't need to know very much about this. This is a pretty interesting diagram when you understand the whole thing. But the one thing I really want to emphasize is you can see here that where it's got the dotted lines here, this is the solution, and the solid lines here are the pure solvent. Okay, so what you can see, and there's no dotted lines here, but it shows the freezing point of the solution here and the freezing point of pure water. So we're assuming I guess this solvent is water, so you can cross that out and put water there if you'd like. But you can see that the change in freezing point is just the difference between what would be zero degrees here and whatever your new freezing point is there. So you wouldn't expect that to be an enormous number, okay? Just as the change in boiling point would be at 100 degrees Celsius here to whatever like 104.2 or something like that. So the change delta TB is only going to be 4.2 or something like that. But the new boiling point would be like 104.2. So recall, in order to get the new boiling point you would have to take the old boiling point and add it to the change in the boiling point. Does that make sense? So like, this is what we ended on last time. So if we say new boiling point TB new, what is that equal? Well that equals the old boiling point TB. In this case it's 100 degrees, right? C, if we're looking at water. And then we're going to add that to, because this is boiling point elevation, whatever we get from that other equation. Delta TB, like that, okay? This is going to be a minimal number, maybe 0.47 degrees Celsius or something like that, right? So the new TB is going to be of course 100, assuming we have enough sig figs, 0.47 degrees Celsius, okay? So you see the increase in the boiling point. Remember this is just that, okay? So I could ask for this or this, and you should be able to do all of that. So this graph is pretty cool. It actually shows you kind of qualitatively what's going on here. It also shows the decrease in the vapor pressure, if you want to look at that. Here's one of these problems, the freezing point depression problems. So it says you add one kilogram of ethylene glycol antifreeze to your car radiator, which contains 4,450 grams of water. What are the boiling and freezing points of this solution? Of course the first thing you're going to have to do is calculate the molality. Remember because delta Tf equals Kf times the molality. So the molality remember is the moles of solute divided by the mass of the solvent in kilograms. So this is kind of a convoluted problem because none of this stuff is given to us except for this Kf so far. So it gives us one kilogram of ethylene glycol. We have to know that that's the solute, okay? Even though it's putting it in kilograms, it's trying to confuse us because we know that the mass of the solvent is supposed to be in kilograms, okay? So we're going to have to convert that kilograms, excuse me, to moles and we know how to do that. Of course we convert kilograms to grams and then using the molecular weight or the molar mass, I mean, you're going to convert that to moles. You see that it's 16.11 moles. Notice the solvent here is water and it's in units of grams so we've got to convert that to kilograms. How do we do that? 4,450 grams divided by 1,000 grams times one kilogram will give you kilograms. Of course this will be 4.450 kilograms. Molality would be moles of solute over kilograms of solvent. We just solved both of those. 16.1 over 4.450 should give you the concentration in molal units. At this point it's apparently 3.62. And now we've got to go back to our table here and figure out the Kf of water because waters are solvent, right? So we go over here. 1.86 is the Kf. Okay, we're doing the boiling point here. So it's both the boiling and the freezing point. But let's do the freezing point since I looked up the Kf of water. So there's your 1.86 degrees Celsius per one molal. We're going to multiply that by what we figured out, 3.62 molal. You see the increase or in this case the decrease in the freezing point is going to be a magnitude of 6.73 degrees Celsius. Recall this is a decrease in the freezing point so we're going to have to subtract that from the actual freezing point. So we got the freezing point of the solution now equals the freezing point of the solvent. So we have to remember the freezing point of water is 0 degrees Celsius and subtract that from what we got of delta Tf there, which is 6.73. 0 minus 6.73 is negative 6.73, okay? So hopefully you guys can do that. I'd like you to go through this example. It's really good. Try it on your own at first and then you can look at the answers. Let's do it for both the boiling and freezing points. Okay, it looks like this kind of got a little small so I don't know if I can even read it. Okay, so that looks better. Okay, so let's talk about the last of the colligative properties. This is known as osmotic pressure. Remember the colligative properties all have to deal with the solute molecules getting in the way of the solvent molecules crossing a physical barrier. The solvent molecules want to freeze but the solute molecules aren't letting them. The solvent molecules want to boil but the solute molecules aren't letting them. Okay, so they're always at this boundary of the two different phases going from liquid to gas, solid to liquid, and so forth. Osmotic pressure is no different, okay? Osmotic pressure does have a new caveat though that we're going to have to realize is also a physical barrier. So when we look at osmosis, what we're doing is looking at two different solutions, okay? So you can see here, this is a pretty good example of looking at that. If you look at this picture one here, you can see if you will the red is, or the big ball is the solute and the little ball is the solvent, okay? So notice if we're looking at one here, you see in compartment A there's all the solute particles, but in compartment B there's none. There's only solvent particles, okay? In between those two compartments is what we call a semipermeable membrane, okay? What is a semipermeable membrane? Well, it's a separation between the two solutions that allows the diffusion of certain particles based on these particle properties, okay? What is diffusion? Diffusion is just the ability for the particles to go through the semipermeable membrane, okay? So let's pretend we'll just redraw this blown up picture here. So this picture A is a blow up of what's happening on the surface of that semipermeable membrane, okay? So notice in compartment A, I think, we've got both solute and solvent molecules, right? But in compartment B we only have solvent particles, like that, okay? What we said is diffusion would be one of these particles being able to go from compartment A to compartment B. That's diffusion, okay? So osmosis in particular is when a solvent can pass through a semipermeable membrane but a solute cannot. So osmosis is the diffusion of the solvent particles through the semipermeable membrane, okay? So what happens is when you have two solutions of differing concentrations that are separated by a semipermeable membrane, the solvent molecules will be able to pass but the solute molecules won't be able to pass and the solvent molecules will always pass through the membrane going from a lower to higher concentration, okay? So if you look here, what is the more concentrated side? A or B concentrated being more solute particles per unit volume, right? So which one has more solute particles? A or B? A has more solute particles, right? Because solutes are these guys. Okay, let's try that again. Which one has more solute particles? A or B? A. A, right? Do you guys see the solutes that... Okay, remember the big ones are solute particles and the little ones are solvent particles, okay? So which is higher in concentration of the solution A or B? A, A, A, right? Because how much solute does B have in it? Zero, right? So what's the concentration of solution B? Zero molar, right? Zero molar. So A must be higher than zero molar, right? So we say this is zero molar. This is bigger than zero molar, right? Like that, okay? Remember the mouth likes to eat the bigger thing, okay? So if we look here, what's going to happen? What do we say? That the solvent wants to pass through the membrane going from a lower to higher concentration. So this arrow that I've drawn probably isn't going to happen, right? So which one's the lower concentration? This is lower than this one, right? So the solvent particles are going to want to go this way, like that, okay? This way, like that. So you can see what happens over time. Initially, we have the volume being the same on both sides, but over time you see the volume of A has, well, it should have showed it increasing a little bit. I don't know if you're able to see that it's increased, but you can definitely see that part B has decreased, okay? That's due to this flux of solvent particles going from the lower to the higher concentration, okay? This is called osmosis, okay? So recall, why is this going to happen, okay? So in fact, what does happen is we have exchange both going back and forth, back and forth, back and forth. But overall, it appears as if the solution is just going from B to A due to the fact that there's these solute particles in A, okay? Why is that? Well, it's because a greater rate can go this way than can go this way. Why is that? Because if I'm a solvent particle behind this solute particle, I try to go through that semi-permeable membrane, but I'm blocked because this guy cannot go through there. So it's kind of stuck, right? So this is like going back to the grocery store, right? And sitting in the very long line, right? So you can't get out of the door if there's somebody in front of you with a lot of groceries, right? So it's the same thing. On this side, right, there's like many, many lanes open, okay? So nobody with a bunch of groceries in front of you, you're just chum, chum, chum, chum, shooting out the door. But here, well, these guys never get out of the grocery line, okay? So the guys behind them will never leave. So overall, you'll see an overall decrease in volume here relative to here and overall increase in volume here, okay, due to the way the solvent particles are moving. Okay, so that's osmosis. Let's talk about osmotic pressure now, okay? What is osmotic pressure? So you can see now we've got a YouTube, okay, before the Internet. This was the only YouTube. So what happens is we've got a semi-permeable membrane here in between these two solutions. Notice on the left here, we have pure solvent. On the right, we have solution. What happens is over time, remember, the solvent particles from the less concentrated will go to the more concentrated of the solutions and you're going to get this difference in height of the two solutions, okay? So this amount of volume has a certain pressure on it. This is what we call the osmotic pressure, okay? So until the external pressure on either side of the YouTube is the same, okay, so applying. So now we have this pressure being equivalent. If we apply more pressure here, right, we can get the solvent to go back to the other side. This is called reverse osmosis. If you've ever heard of a reverse osmosis plant, that's how you get sewage water and river water and stuff back to good drinking water, is that you squish it through a reverse osmosis plant and make the solvent molecules go the other way. This is like how the astronauts and stuff, you know, are able to drink their water, right? Because they don't have, you can't take a bunch of water in space, so you've got to keep recycling your water, you know? So you kind of, I don't know, do whatever into a little reverse osmosis packet and then squeeze it through and go back and have pure solvent molecules again, okay? So osmotic pressure, of course, there's going to be some sort of equation because it would be too easy if that were it, right? So osmotic pressure, the actual definition is the hydrostatic pressure, so that's the pressure caused by the height of the water in the YouTube. Remember, it's this thing here. Usually you'll see osmotic pressure being pi. The symbol is pi, so maybe you should want to change that instead of having it P there, make it a pi. So pi like, yeah, like pi, peach pi. No, no, no, no, no, it's the Greek letter pi, okay? So it's just like a Greek person talking. Just like we say P is P, right? It doesn't have any number associated with it, okay? Yeah, okay. Okay, no, so okay, it's just like anything else, right? It's just a symbol for it, okay? R though, R, guess what R is? Do you guys remember what R is from the gas laws? No, no, it's going to be 0.0821, right? So R is going to be the same R from the gas laws. And remember, I have to give that to you, okay? And it's that 0.0821, okay? Leader ATM over Kelvin, okay? So, and remember, big M is molarity, and T, T is going to be in what temperature units do you think? Kelvin, always in Kelvin, okay? So where it says big M here, instead of using just molarity, it's called something different, even though it's the same units, it's called the osmolarity, okay? And the osmolarity tells us the molarity of particles in solution, okay? As opposed to the molarity. So let's figure out what I'm talking about here. If I say, okay, I've got NaCl, solid, and I put it into water. It's going to dissolve into its constituent ions. Na plus Cl, Na plus, right, everyone? Plus Cl minus, right? Okay, so if I have a concentration of, well, let's just make up something. 0.10 molar NaCl, what's the concentration that I have of Na plus? What's the concentration? Everybody should be like, blowing me out of the room with their answer right now, okay? What is the concentration of Na plus? 0.10 molar, thank you everybody, okay? Everybody else needs to know that like this, okay, from now on. How did you figure that out? What's the ratio of NaCl to Na plus, here? One to one. So how did we figure that out then? Yeah, you times it by one. It's very difficult, right? Okay, so let's ask ourselves then, what's the concentration of Cl minus ions? 0.10, right? 0.10, how did you figure that one out? Because we got a what-to-what ratio of NaCl to Cl minus ions. One to one, very good, very good. One to one, okay, cool. So if I asked you, what's the total concentration of Na plus and Cl minus ions? What's the total concentration? Put together. What's the total concentration there? Thank you, 0.2, right? So everybody, 0.1 plus 0.1 equals 0.2, okay? So if we add these two things together, okay, what do we get? Let's try that again. What do we get? 0.2, okay, that's really good. Okay, so cool. So we say for the total concentration of reactants we've got, we've got 0.10 molar. The total concentration of products we got here is 0.2 molar, okay? What we say is that this is the concentration of particles we have in solution, okay? This is the concentration of particles in solution, like that. So concentration of particles in solution is known as the osmolarity of the solution. It's the same units as the osmolarity of this solution is 0.2 molar, okay? So you guys are going to have to be able to do that on your own. But as you could tell, it's not as difficult as you might first initially think. Okay, so again, instead of big M here being just the molarity, right, it's actually going to be the osmolarity, okay? So if it makes you feel better to write this equation like this, I equals, instead of big M, we'll say osmolarity, right? Times R times T, that's fine too, okay? So you've got to watch out that you're not just, if I say, okay, the molarity of NaCl solution is 0.1, you're going to have to figure out, oh yeah, NaCl breaks up into Na plus ions and Cl minus ions. So each of those is a 1 to 1 to 1 ratio, so I have to add those two up to get the osmolarity, okay? So try to calculate the osmolarity of this thing. Okay, it's 5.0 times 10 to the negative 3 molar Na3PO4, sodium phosphate. Try it on your own, okay? And then you can go ahead and calculate the osmotic pressure here. Remember the difference that I told you in the calculation if you'd like to change this big M to osmolarity. Remember we have to change this temperature 25 degrees Celsius to Kelvin. And here's another one for you. You can calculate the osmolarity of the solution if I give you the osmotic pressure and the temperature, okay? You just rearrange this to calculate the osmolarity. And then there's one without the answer for you. So why is this important? Why does it matter, right? It must matter something or we wouldn't be talking about it, right? Well, of course living cells contain aqueous solution and those cells are also surrounded by aqueous solution, okay? So these two solutions, the inside of the cell and the outside of the cell, are almost inevitably going to be of different concentrations, okay? So the cell, so it's a natural process for water to or solvent to flow to, from lower concentrations to higher concentrations. So how does the cell prevent all of its water from flowing out or if it lives in a kind of a salty environment? Or how does it prevent itself from exploding because of all of this water constantly flowing in if it lives in a non-salty environment, okay? So cell functions requires the maintenance of the same osmotic pressure inside and outside of the cell. So when the solute concentration of fluid surrounding cells is higher than the inside, this results in a hypertonic solution. So outside the solution is hypertonic. So let's just think about, this is just a picture of a cell, right? But you can imagine this would happen to, like, you, if you ate a lot of salt or something like that, you could pretend the same thing. You're the cells in your body, right? So this, what does it say? What's the first thing we're doing? High concentration, right, of salt. Salt is not just necessarily NACL, but any ionic compound that breaks up into its constituent ions, of course, right? So if we have a high concentration outside, we call that a hypertonic solution. So tonic means just salt, okay? So hyper means, you know, high going a lot or a lot of something, right? So hypertonic means very high salty stuff, okay? So hypertonic relative to this, what's going to happen? This thing's going, all the water's going to flow out of the cell, and we're going to get like some, like shriveled up cell, right? This is called carnation. So the water all flows out. And if the solute concentration of the fluid surrounding the cells is very low, we call this a hypotonic solution, right? And what happens? Well, if it's too low, instead of doing that, it's going to flow into the cell, and that's our cell now, right? Exploded, okay? This is called hemolysis. Lysis here, this means to break, so the cell blows up. So isotonic solutions have ideal osmotic pressures. Isotonic means the same salt concentration. Tonicity is, again, salt concentration. Iso, meaning the same, have identical osmotic pressures, and no osmotic pressure difference across the cell membrane. So you can see here, hypotonic, hypotonic, and the cell looks really nice and red blood cell-like in the normal isotonic solution. Okay? And you can see this also happens to cucumbers, right? When you put them in a hypotonic solution, you ever wondered how a pickle was made? That's how it's made, okay? So you put a cucumber into a hypotonic solution, and what happens? All the water flows out of the cucumber, and you get a little cucumber. That's called a pickle, okay? Okay, so let's look at cations in the blood and cells. Okay, so you notice the concentration of sodium ions, and the blood is 135 milli equivalents per liter. So this is like a thousandth of an equivalent per liter. Remember, we know how to do equivalents per liter. And inside the cells, it's about three to five milli equivalents per liter, okay? So the combination of those two numbers is about 140 milli equivalents per liter, okay? And you can see here, potassium in the blood is about 10 milli equivalents per liter, and in the cells, it's about 1.25 milli equivalents per liter, and if you add those two numbers up, it's about, it's not 140, but it's pretty close to 140, right? So that's that isotonicity that you have between the cell and its extracellular membrane. In fact, you have to have this discrepancy of concentration of sodium outside of the cell and the concentration of potassium inside the cell, because of course what happens is the main energy source for the cell is the sodium potassium pump, okay? The sodium potassium pump actively transports these ions back and forth, giving the cells all of their energy. And of course you all your energy, and that's why we're able to walk around and talk and stuff like that, okay? So this all has to do, of course, you know, we've got to remember that humans and animals and everything, it's all chemical systems, okay? They're all chemical systems. So in order to understand all of this stuff on a macromolecular level, you really need to understand it on a chemical level. So of course we know that danger to the body occurs when sodium and potassium in both the blood and cells becomes too low or high. If you get your sodium too low, you decrease your urine output, dry mouth, flush skin, fever, too high, confusion, stupor or coma, same thing. Too high, potassium death, too low, potassium death, okay? So no good. Of course we can't just have positively charged ions all over the place in our body without having any counter ions to those positively charged ions. The common counter ions that you'll find of course are the chlorine anions. This gives us that acid base or ionic charge balance. This helps maintain ionic or osmotic pressure because remember osmotic pressure doesn't care about what type of particle you have just that it's in your solution, okay? And it helps maintain oxygen transport. The bicarbonate anion, this is what you breathe out all the time is carbon dioxide. So what happens is you break down your food sources, all your carbon sources, that's mostly your food, right? So all your carbon, you get rid of your carbon through breathing out, carbon dioxide, you get rid of your nitrogen from your food by going to the bathroom. So every time you breathe out, you're releasing, you're taking some of this bicarbonate ion which is in your blood, right? This is why your blood going from your body to your lungs is blue, right? Because it doesn't have very much oxygen and it's got, instead of oxygen it's got these bicarbonate ions in it and when you take it to your lungs and get rid of that carbon dioxide then of course your blood gets oxygen back, changes its color back and of course changes its ionic concentration too, okay? So, and then there's other sorts of solutes in the blood, what we call blood clotting factors, antibodies, albumins, these are proteins that carry stuff around. So of course, just like you know, like dissolves like, most of you is very polar because you're 70% water, okay? So you're like a water bag walking around, right? But you gotta have some non-polar stuff to make you work, okay? So if I'm a bag of water, how do I get that non-polar stuff to transport around inside of me because it won't dissolve in the water? So what you have is these albumins that are inside of the albumin so it's got kind of two layers. You can think of it like this, it's not really so simple. You can think of it like a, it's got like a non-polar inside and on the outside it's very polar, okay? So since the outside is in contact with the water the whole thing's being able to be dissolved but the stuff that is non-polar that you want to use inside of you will go inside of here and be dissolved and then when it's needed, your body can take it out and use it, okay? So these are other types of solutes that you find and then other types of proteins are transported as colloidal suspension so these are particles within the solution that are, you know bigger type particles, micrometer type particles, okay? And of course you know that blood transports waste and nutrients. Okay, so let's just go ahead and start chapter 8 since we're so excited about getting the chapter 8 slides this morning and I hate to disappoint you guys. Hi, you couldn't get them? Well that's because they weren't up until 8.15 or 8.30. Yeah, well like I said, it was me because I don't write lectures until about 4 o'clock in the morning, you know? Right down the street. Anyways. Right down the street. Directly west of the entrance one. Okay, anyway, so let's start talking about chapter 8. Thank you. Okay, so now we're going to talk about reaction rates and equilibrium. We'll just start to introduce this subject since we only got about 5 minutes. So you guys remember using these glow sticks, right? Have you ever used a glow stick? Never. That was one of the most confusing looks I think I've ever had. Somebody tell me a glow stick. Okay, anyways, if you've never used a glow stick then you might not know these pictures but I like this picture, it's pretty cool. Anyways, let's just start talking about thermodynamics. So thermodynamics in general is the study of energy work in heat and in fact all three of those things are essentially the same thing. Okay, they're all energy. So when we apply that to chemical change we could potentially calculate the quantity of heat obtained from the combustion of one gallon of fuel oil. That would be a nice thing to be able to calculate when we're talking about reactions. What about physical change? Well, we can determine the energy released by boiling water. Okay, so the laws of thermodynamics actually help us to understand why some chemical reactions occur and others do not. Okay, so this is what we're going to be talking about for probably the next week is why do these reactions occur, these ones and why do these other ones not occur? Just like this one, you can see this chemical reaction is happening very a lot, right, very a lot, right, in this beaker and not very much in this beaker. Okay, not very a lot in this beaker, yeah. So you can see here, I don't know if you guys know but these are actually digital thermometer readings. So you can see this one's at 59 degrees, which is twice room temperature. This one's at .2 degrees, which is almost freezing. Okay, so this reaction is happening faster than this reaction here. This is actually a measure of rate, but it kind of does tell us what's going on. Okay, so recall, these are things that you know already. Molecules and atoms in a reaction mixture are in constant random motion so they're not just chilling, you know, in the reaction mixture asleep. They're like zipping around, they're like flying all over the place or if they're in the aqueous medium swimming all over the place, right and all of their bonds are like flailing about as fast as you can imagine them being. Okay, a good representation would be something like that, you know, doing something like that. Okay, so, but only some collisions, those with sufficient energy will be able to break bonds in molecules. Of course, when we have a molecule and we break the bonds, we make a different molecule. Okay, and when reactant bonds are broken, new bonds may be formed and when new bonds are formed, we make a new molecule, these are product molecules. Okay, so let's talk about energy and energy experiments. Okay, in order to talk about energy and energy experiments, we actually have to define some things that may be relatively obvious to define and you might say, well, why do we have to do this? But it really does help, okay? So remember, energy cannot be created or destroyed, okay, unless you're Einstein, then you can, you can take some mass and convert it to energy. But for us normal people, right, energy and chemical reactions won't be created or destroyed. So, but the measure of energy can change, okay? So in order to determine where the energy is going, we have to define the system and the surroundings, okay? So, like this picture is being shown here, this is the reaction that we did in lab, if you recall this one. The system contains the process under study, so that might be the combination of the test tube and the beaker here. The surroundings is the rest of the universe, it's everything else, okay? So, like, when I have a cup of hot coffee or something and I put my hand on it, you know that the energy flow is going from the coffee to my hand. How do I know that? Because my hand is getting warmer, okay? The reaction would be, or the phase change in this case would be the system, that would be the cup of coffee. The surroundings would be my hand and everything else, okay? The rest of the universe. You can think of it pictorially like this. The system being the beaker heat flowing out or heat flowing in. This would be like boiling water, right? And this might be like freezing, okay? So, energy can be lost from the system to the surroundings, like here. Or energy may be gained by the system at the expense of the surroundings, like the sun shining on the earth and making photosynthetic life, right? So, this energy is usually in the form of heat and this change can be measured, okay? So, since everybody wants to get out of here, I'll let you get out of here. Have a good day, guys.