 Okay, so this first one says calculate molar mass of magnesium sulfate pentahydrate, okay? So let's figure out how to do molar mass of magnesium sulfate pentahydrate. So the first thing we've got to do is figure out what magnesium sulfate pentahydrate is. Hopefully you guys know that since we're going to do problems on that all morning. Magnesium sulfate pentahydrate. This compound here is called the hydrate. It's got these water molecules associated with each one of these formula units, okay? It's got five water molecules associated with it. So when we're talking about the molar mass, we have to include those five water molecules within the molar mass. So when we're talking about molar mass, we're not talking about molecular weight. It's different, right? Molecular weight is measured in units of what? AMU, right? And molar mass? Grams per mole. Per mole. Molar mass, grams per mole, okay? So how do we figure out what the molar mass is here? We can do the same thing as looking for, like, formula weight or molecular weight, okay? Except we have to remember that if we look up at the rear end of the table, it no longer tells us AMU of grams per mole. Are we okay with that? So let's just write it. So molar mass of this compound is going to be one times magnesium, right? So 24.3050 grams per mole plus one times sulfur, 32.065. And then, well, some people would like to do all the oxygens together. I like to just keep the water molecules up, because I know water is 18.02. So how many water, or how many oxygens in the sulfate part? Four. Four plus five waters. Magnesium sulfate antihydrate weighs 210.47 grams, okay?