 Okay, so this one says which has a higher boiling point? Cis-1,2-dichloroethylene or trans-1,2-dichloroethylene? So, since you guys are in gym chem, you don't know what these two molecules look like, so I'm going to draw them for you, okay? So, cis-1,2-dichloroethylene, I don't really want to draw them without the carbon, so I'm going to draw all the carbons in there too. Okay, so this is the cis, because the chlorines are on the same side. This one's going to be the trans, because the chlorines are the big, are on opposite sides. In fact, this is one of the first things you'll learn in organic chemistry. So trans is this one. Okay, so it's asking which of these has a higher dipole moment? So, what were the two things that led to an increased dipole moment? There were two things, what did we say they were? Anybody, I've got 30 people in here. Molecular weight is one of them, okay? Do these things have different molecular weights? No. No, okay, so what was the other thing that led to high polarity? Or in the case of the ones that hydrogen bond, yeah, hydrogen bonding, but polarity in general. In fact, these ones don't hydrogen bond because they don't have an n, an h, or an f, right? But you can see, right, the cl is more electronegative than the carbon, right? So, we're going to have, in this case, two dipolaros like that, okay? These ones you can effectively say are non-polar bonds. And in this one, we've got dipolaro like that, and a dipolaro like that, okay? So, what can we say about these two molecules? Can anybody help me out? One of them is what, and the other one is what? One's polar. One's polar, and the other one's non-polar, okay? How can we tell which one's polar and which one's non-polar? The direction. The direction of the dipolar, right? So, if we add those two vectors together, this one's going to, and we've done this before, okay? We're just doing this outright, so this one's polar, right? And these two cancel each other out, so non-polar. So, which would you expect to have the higher boiling point? One on the left or on the right? Left. The left, right? Why? Because it's polar, okay? Polar molecules have higher boiling points than non-polar molecules. Everybody okay with that? Yes. Okay. If they're the same molecular weight. Okay. Okay, guys. See you next on Wednesday. Good job.