 Okay, so let's do another one of these specific rotation problems. This one we're actually finding the observed rotation. It says, calculate the observed rotation of a solution of 0.5245 grams of S1-amino-1-phenyl-ethane diluted to a volume of 10.0 mls with methanol at 20 degrees Celsius using the D-line of a sodium lamp and a 1.00 decimeter tube. Specific rotation of this material is negative 30.0 degrees. Okay, so let's figure out what the observed rotation is. So how do we do this? Y'all, what's the first step we need to do? Formulate. The formula. Y'all remember the formula? Yeah. So what is it? So this is called specific rotation, right? Equals what? Observe. Divide. Divide. Path length. Concentration. Concentration. Okay, this time we're looking for observed though, right? So we're going to have to rearrange this equation to solve one. Okay? So I'm just going to rearrange it. Observed equals alpha D or specific rotation times path length times concentration. Okay, so now it's, well, no, we don't have the concentration yet, right? So we've got to figure that. Okay, so let's go over here to figure out what the concentration of our compound is. So, and we want that concentration in grams per mil. So we've got those units already. So that's nice. 5245 grams per 10.0 mils. Oh, I guess I don't need to. So we have concentration. We have path length. We have observed rotation. So our specific rotation. So 1.0.0.5.245 grams per mil. Like that. Negative 1.5.6. I'm sorry? Negative. Oh, you've already solved it. Okay, wonderful. Now let's solve it together. So what do we got? Negative 30 times 1 times 0.05245. And what did you say? Yeah, so how many safe things though? Only three. Okay, so negative 1.57 degrees. So that's the observed rotation. Is everybody okay with doing that one? Okay, wonderful. Questions before I kill it? No. Questions? You sure? All right.