 Okay, cool. So this one's number two on exam 2b. Calculate the number of moles of calcium chloride in 72.6 mils of a .254 molar calcium chloride solution. So what do we know already? So the first thing we want to do is write down the things we know. So volume, we're eventually going to have to figure out liters, but we know it in milliliters. 72.6 mils. Well, let's convert that to liters. We know the molary, which is zero point, that's what we're looking for. So what equation do you know that correlates these three variables? It's the molarity equation. Molarity equals number of moles of solute, the volume and solution in liters. We're trying to figure out the number of moles of solute there. So now we want to isolate that variable. We've got the Vl in the same side of the equation, so we want to get rid of that. So all we do is multiply by Vl. That cancels there. We've got Vl there. So we've got number of moles equals the volume in liters. Let's plug these two numbers in. So the volume in moles is volume in liters, which is 0.0726 liters multiplied by the molarity, 0.254 moles per liter. Letters cancel, number of moles, which is 1.3, 1.84.