 Let's try this problem. It says, calculate the pH of a buffer that is 0.2 molar in formic acid and 0.15 molar in sodium formate. Then it gives you the Ka for formic acid is 1.8 times 10 to the negative 4. So I wrote out the formulas for formic acid and sodium formate for you all. You could actually do a nice table for this one, like I've showed you in the past and some of you have done on this one. But actually, when you have the conjugate acid and conjugate base of the same thing, right, so the pair, you can, if you're looking for the pH, you can use something that's called the Henderson-Hasselbach equation. Do you remember doing that? Okay, so the Henderson-Hasselbach equation. You guys remember what the equation was? Yes. pH equals pKa plus the log of a minus concentration over hA concentration. Okay? So which one's a minus and which one's hA? And so the conjugate base is hA. Okay? The conjugate base is hA. Okay? So, well, we've got the concentration of those in molarity, but we don't have the pKa. Right? So how do we do the pKa? Remember, the pKa is the negative log of the Ka. So let's figure out what that is. So it's going to be negative log of 1.8 times 10 to the negative 4. It should be like 3.0. The concentration of a minus and we have the concentration of hA. Right? So it's just a flaming check rule. So it's a lot easier than doing a whole ice thing. Right? So 3.74 log of 0.20. So 0.15 divided by 0.2, 0.75. Take the log of that. Negative 0.125 and add that to 3.74 and I get digits 3.6. So that's going to be the pKa. And like Frank showed us right before we started the recording, we could actually have done this with an ice table, you know, using the weak acid ice table. But Henderson has a lot of kind of makes it a little easier. So that's going to be the pKa. And like Frank showed us right before we started the recording, we could actually have done this with an ice table, you know, using the weak acid ice table. But Henderson has a lot kind of makes it a little easier. Okay. Can we kill it? Are there any questions? No, okay.