 OK, so let's do this problem now. The clear liquid shown is carbon disulfide. So I don't have any with me, so we'll re-record this one in the lab. It's composed of carbon, which is the black solid shown, and sulfur, which is the yellow solid shown. So if carbon disulfide contains one carbon atom for every two sulfur atoms, so let's write that down. One carbon atom for every two sulfur atoms, what is the molecular formula of carbon disulfide? So molecular formula, remember, it's these three atoms, stick them together. So carbon disulfide, and you write them in the way that it's written or said. So carbon goes first. There's only one of them. So, well, let's do the sulfur first. There's two of them. So you put a subscript 2 there. In fact, this is the molecular formula for carbon disulfide. Why didn't we put a 1 there? That why? Because it's implied that there's a 1 there, because you already got that carbon. So you need to actually tell me how many sulfurs you got, because you got more than one. You got only one carbon. You've already told me that if I put it right there. And in fact, if you want to know what the molecular structure of this looks like, the reaction that we talked about, we'll talk more about this down the road.