 OK, so let's try this kind of generalized pH problem. It's a little more complicated because you're actually looking for the mass of sodium hydroxide. So this one says, how much sodium hydroxide in grams is needed to prepare a 546 milliliters of solution with a pH of 10.00? So let's attempt to do this problem. So the first thing we need to know, of course, is that the pH calculation or equation is pH equals the negative log of the hydronium ion concentration. OK, so from that, you can figure out, well, what's the hydronium ion concentration? And that's going to be 10 to the negative 10.00. So you can figure that it's 1, 2, 2, mole like this. So from that, you're going to figure out, well, what's the OH concentration? So remember, kW equals the hydronium ion concentration times the hydroxide concentration like that. And kW is something that's going to be given to 1.0 times 10 to the negative 14. So from that, you should be able to figure out the hydroxide ion concentration. That equals kW divided by hydronium ion concentration. So that equals 1.0 times 10 to the negative 14 divided by 1.0 times 10 to the negative 10. So that's going to equal 1.0 times 10 to the negative 4 mole. So does everybody follow me there? So the other thing you want to know is, well, the ionization reaction equation for sodium hydroxide, so when you put that into the solution, it ionizes to van. So the concentration of sodium hydroxide is going to be the same as the concentration of hydroxide since everybody follow me there. So let's just formally do that. So that's the molar of hydroxide. So for every one molar hydroxide, we have more molar. So the concentration of NaOH is going to be 1.0 times 10 to the negative 4th mole. So we have the volume of solution. And if you recall, hopefully you do, that mol, molarity is moles per one liter like that. So that's, remember, just a fancy conversion factor. So can I erase this portion of the stuff that we've done? Is everybody OK with that? What do we got? We're saying the volume of the solution, we're looking for the mass of sodium hydroxide. So let's look for the number of moles of sodium hydroxide. We've got. So remember, molarity equals moles per volume. So the number of moles is going to be 546 milliliters of 1,000 mils at the bottom, one liter at the top. And then multiply that by that molarity, 1.0 times 10 to the negative 4th moles per one liter of solution. So what will happen is cancel, cancel, cancel, cancel. So we got moles left, right? So well, since I don't have any more space, let's just solve that problem and then we'll go to the next problem. So 546 divided by 1,000 times 4,6 times 10 to the negative. Moles like that, is everybody OK with what we've done so far? OK. So we want to figure out, well, what's the mass in grams of sodium hydroxide? So if I remember correctly, the molar mass of sodium hydroxide is 40.00 grams per mole. Yeah, that's correct. So let's just do it this way to formalize the whole thing. So moles of sodium hydroxide at the bottom, we're going to put one mole of sodium hydroxide. At the top, we're going to put 40.00 grams of sodium hydroxide. Cancel, cancel, and that's what we were looking for, right? So thanks, goodness, after all that, we got to the right unit. So let's just multiply that number we have in our calculator by 40. And this, of course, is going to go to three significant figures. So it's going to be 2.18 times 10 to 3 grams of sodium hydroxide. I may be would have asked that in Miller hands, but I don't know. Does anybody got any questions on that one? Wonderful.