 So this one says acrolein, and the structure is shown there, absorbs its maximum wavelength at 217 nanometers with a molar absorptivity of 16,000 mils per meg per centimeter. What is the concentration weight, or the weight concentration required to observe an absorbance of 0.80 when the path length is 1.0 centimeters? So again, we're using Bayer's law for this one here, but we're solving for concentration. So what is concentration? That's what we're looking for. And it says the weight concentration. What that means is milligrams per milliliter. So of course, all we're going to do is rearrange this equation. So c equals a divided by epsilon b like that. So c is going to be a is 0.80. So divided by epsilon, so epsilon is this. So 16,000 milliliters. And this is 1 milligram times 1 centimeter. And we're going to also divide it by path length. So we'll just put it over here. 1.00. So is everybody cool with me doing it that way? So again, I just flipped this over because we're dividing it. So that will allow us to cancel our units out centimeters, centimeters, giving us a mid per mill weight concentration. Does that make sense? So notice the molar absorptivity units are different in this. And the concentration units are different in this one than the last one we did. So molar absorptivity and concentration units kind of mirror each other. So now all we've got to do is pull it in. So 0.8 divided by 16,000. 5.0 times 10 to the negative fifth milligrams per mole. So that would be the concentration. Okay. Are there any questions on this one? Again, pretty straightforward, I think, just rearranging the equation.