 Okay, so let's do one of these Born-Haver processes questions. So in these questions it's asking, well, what is the lattice energy going from these gaseous ions to the actual solid? As you would imagine, that's going to be going down in energy, so that's an exothermic process. But we can't measure this directly from experimental data because we can't get a bunch of these ions in the gaseous phase very easily. So we can use kind of a Hess's law approach to this kind of equation because we can figure out all of these values experimentally. So it would be nice to be able to figure out this. So if we add up all those other values, we should be able to get that, okay? So let's see what's going on in this particular graphic here. So what this is is kind of a pseudo-energy diagram, so you notice I have energy increasing there. So let's kind of label the pieces of that diagram with respect to these numbers here, okay? So if you notice, this equation here is effectively going from here to here, okay? So that would be the heat of formation from the solid sodium plus one-half chlorine gas goes to one mole of sodium chloride. So what does it mean one-half chlorine gas? Why are we using that? Well, it's because we want the heat of formation of one mole of sodium chloride, so that's why we're doing that. So don't let that confuse you, okay? So let's just put that, is everybody okay with doing something like that? Okay, wonderful. Okay, so here we see what's the difference between this equation and this equation. Can anybody tell me what the difference is? Sodium is a type of particle gas. Yeah, the sodium went from a solid to a gas. So what you want to do is come over here and look for that process, okay? Again, remember, all of these numbers are given to you on these various tables, so like the bond energy table, the electron affinity table, the atomization table, the ionization energy table. So you're going to have to be given all of these tables in order to do this problem, okay? So what did we say? Sodium solid went to sodium gas, so that's the delta H of the atomization of sodium. Okay, so let's label that. Okay, so hopefully you see this one. We have one-half chlorine, two gas going to just one chlorine atom gas. Over here, right, the bond energy of chlorine is Cl2 goes to 2Cl. So the bond energy of that is 242, but here we're doing one-half of that. Is everybody okay with seeing that? So what we're going to do here is just multiply the bond energy of that Cl2 times one-half. Okay? So hopefully those are, by those big enough for you guys to see. Okay, so now we see, hopefully, that the sodium atom is going to the sodium ion, so it's losing an electron, okay? So what do we call that? The ionization energy, or the first ionization energy. Okay, so let's label that there, and all of those three processes, hopefully you would expect them to be endothermic in nature, okay? So the chlorine getting an electron is going to be exothermic, that's a nice, a good process, right? And we call that, of course, the electron affinity of chlorine. And then, of course, the crux of the problem, what we're actually doing here is to find that lattice energy, so that would be the lattice energy of sodium chloride, okay? So remember, in these equations, this is a state function, so we know we could just go from here to here, and that would be the same distance, okay, because it's a state function as adding up all of these other things, okay? So effectively, hf here of sodium chloride equals the additive of all of those other things, okay? Is everybody okay with that? So let's set up that equation, because I'm going to have to erase this, because we don't have enough room to write the equation and solve the problem, okay? So let's have the equation, and then we'll erase our little graphic here, is everybody okay with that? So delta hf, standard conditions of NaCl equals delta h, atomization of sodium plus the bond energy of chlorine 2, plus the ionization energy of sodium, plus the electron affinity of chlorine, remember that's going to be a negative number, okay, plus the lattice energy of sodium chloride, another negative number. So any of these down processes are negative numbers, any of the up processes are positive numbers. So everybody okay with setting up that equation there, okay, wonderful. So once you get that written down, and this written down on all arrays, is everybody, I mean have you all written it down already? Okay, so I'm going to erase this energy diagram as long as it took me to write it So now what are we solving for? So we're solving for this lattice energy of sodium chloride. So let's isolate that variable here, okay? So we can move this to this side, or let's just move everything to the other side. So the lattice energy of NaCl equals delta hCl minus delta h of sodium minus the one path of bond energy of Cl2, move this one over, okay, minus the ionization energy of sodium, and then move this one over too, okay, minus the electron affinity of chlorine, okay? So would that be the new equation there from what we see up there? So now it's just a plug and chug problem, okay? So let's put all of these values in, okay? So heat information negative 411 kilojoules minus the atomization energy, kilojoules minus one half the bond energy, which is 242 kilojoules per mole, minus the ionization energy, kilojoules per mole, and then minus the electron affinity, which is a negative number, so it's a minus of minus, okay? 64 kilojoules, it was just to make sure we're still there. Let's just add these guys up and see, hopefully we get a negative number, remember that down arrow, okay? So we did 411 minus 108 minus 121 minus 500 plus 364, and I got a number, so there's a decimal point there, I don't know if you can see that, but this would be two, three digits or to that decimal, so I get a number 7, 7, 6 kilojoules per mole, notice the negative sign there, okay? That tells me that it's an exothermic process, as you would have expected, okay? So are there any questions about doing something like this? I know it's a long and involved process, but just make sure if you do it stepwise, you should be able to logically come up with this kind of an equation, okay, if you can, if you have, don't memorize this, okay? I mean you can if you like to memorize stuff, but you get all of that from those tables, okay? So again, I think it's possible that you can do these types of problems, I know it looks a little daunting at first, okay? Any questions before I kill it? Okay, wonderful, good job, guys.