 Okay, I guess so we can start right here. Hey ladies. So this is the first problem on the practice exam. Calculate the molar mass of C5H12, okay? So C5H12, that's a protein. Calculate the molar mass. So you can get the molecular weight of this compound just by looking at the periodic table, okay? So the molecular weight, that's going to equal the amount of carbons, so carbons, you've got 5 of them, right? And you add that to the amount of hydrogens. The hydrogens, you've got 12 of them. And if you look at the periodic table, it tells you that carbon, its average atomic weight, is 12.011 AMU. And then hydrogen's average atomic weight is 1.00794. Multiply those two things together then add them up. So let's do that. So 5 times 12.011, that equals 16.055 AMU. And 12 times 1.00794, that equals 12. Those two numbers together, so that's the molecular weight, okay? Now this says in the problem, what's the molar mass, okay? So molar mass, y'all, is the number of grams per mole, okay? That's what that means. So how much does one mole weigh? So think of the molar mass to be equivalent or approximately this number but in grams per mole. So it's going to be 72.150 grams per mole. You can figure this out more precisely if you multiply this by this conversion factor, 1.66 times 10 to the negative 24th grams per 1 AMU. Cancel those out, right? So 72 times 1. That's per one molecule of this stuff. And then you can take that number and multiply that by this number, 6.02 to the 23rd. And again, you'll get grams per mole out of this calculation. And hopefully it'll be something like this number here, okay? So just multiply that by how we got this number. You get 72.125 grams per mole, okay? So you could have done it this way if you like doing it the long way, okay? Or you could just do it this way. Those are two different ways. I thought that was like the whole problem. No, it's the same problem two different ways. This is like the more precise thing, right? If you want to, you don't have to. Like I said, this is more of an approximation, you know? That's like the long way to do it, okay? But look, the same answer, right? So notice this is an approximation, you know? Actually, this is an approximation too, because this number is approximate, hey. And it all depends really on what periodic table you use to get these numbers to where your sig figs are, you know? And honestly, on these types of problem sites really tend to not really care as much about sig figs. Not to say that I don't care, you know, but not as much. So that's how to do the first problem. I think the strange thing in this is, or the hard thing to remember in this problem is like that it says mole or mass, so we need to do grams per mole, okay, instead of AMU.