 Okay, so let's formally calculate how to get the molar mass of something from knowing its molecular weight. Okay? That's something in this case will be water. Okay? So we have the molecular weight of water being 18.02. How did we figure that out? Well we added the atomic weight of hydrogen multiplied by 2 and then added the atomic weight of oxygen to that. Okay? We got 18.02 AMU. Well a mole, how many items is in one mole? 6.022 times 10 to the 23rd or Avogadro's number, right? So if I wanted to figure out how many AMUs a mole weighed, what would I do? What would I do? If I said this pen weighs, I don't know, 10 grams, how many grams does 4-pens weigh? How would I figure that answer out? Multiply by 4, okay? So if I knew how many one molecule weighed and I wanted to know how many a mole of molecules weighed, what would I do? Multiply by Avogadro's number 6.022 times 10 to the 23rd. Is everybody okay with that? So remember, try to not compartmentalize everything into chemistry class. Remember we can do it with these kind of pen equations and stuff like that, okay? So just like we were doing, we would have to multiply this by 6.022 times 10 to the 23rd. Now remember, a lot of times it's convenient to say per mole, because that's how many things are in one mole. Do you remember us doing this, Colin? So per mole. So, and I get this number, 1.25, what are my units here? Can anybody help me? Amu per mole. I'll just write it like that so I can see everything, okay, in a ratio form. Remember, you guys are beginning chemistry students, so it's good to kind of write things like this, okay? So I want to convert that amu to grams now. And I have the conversion factor to do it, so I know all of you can do that. So I'm just going to jump that step or jump asking you and just write that step, taking it for granted. And what are my units of this answer going to be? Grams per mole. Grams per mole, what is the name of that unit? What is the formal name for that thing? The what? The molar mass. The molar mass, okay? Remember, whoever's saying that isn't going to be there on your exam, so you've got to remember these types of things, okay? So the molar mass, that's going to give me, because it's grams per mole, is everybody cool with that? So I'm just going to take that answer and multiply it by 1.61 e24. Oh, and behold, look at the number I did. 18.02 grams per mole, okay? So that's pretty interesting to me. Is that interesting to you guys? Or at least quirky in some way? Why is that weird? Same number as this number up here. It's just different units, right? So we could have effectively gotten this number from just doing one. Changing the units after we looked at the periodic table, right, and added all those things. Is everybody cool with what I'm saying? Okay. I'm glad you guys are learning to start being able to read my mind. Any questions on doing something like this? Again, I guess I should say one other thing is, and I know you guys mentioned it, all you've got to do is change the units to get these things, okay? So it's not any, don't do this every time. Don't do this every time when it's a what is the molar mass, okay? This is just a formal calculation. Can I kill it?