 Okay, so let's try this problem. We'll just do the first part of it. So calculate the concentration of hydroxide ion in a solution that has a hydronium ion concentration of 1.0 times 10 to the name of the fifth mole. So the first thing you need to remember is that KW equals the concentration of H3O plus times the concentration of OH minus and that equals 1.0 times 10 to the negative 14. So everybody's cool with that, right? The other thing you know that the problem gives you, it says that you know the H3O plus concentration and that equals 1.0 times 10 to the negative fifth mole. So it asks you, what is that then? Hydroxide ion concentration for OH minus. So could I do this? We know KW, we know H3O plus but we don't know this, right? All we gotta do is rearrange this equation. Isolate the variable that we're looking for, right? So the equation is going to convert to OH minus and we're going to take KW and divide both sides by H3O plus, right? So when we do that, anybody get it? So is there units after that? Yes. Yes, concentration means molar, okay? How did I figure this out in my head? It's negative 14 plus times what you do, okay? So whenever anything's on the bottom, usually if it's just this 10 to the minus 14, once these numbers change, then you're gonna have to do it in your cup. Is everybody okay with this? Okay. So in a second, we're going to finish this problem up and say is this an acidic or basic solution? Okay. We'll see.