 What is the solubility of calcium hydroxide in 0.10 molar calcium nitrate? The Ksp of calcium hydroxide is given to us at 6.5 times 10 to the negative 6. Okay, so get into your mind that calcium and the lower group 2s are insoluble. Okay, so how do we do this particular problem? We're going to have to first write a reaction equation just how we do every other problem, the equilibrium problem. So calcium, so we're not going to use the calcium nitrate because the nitrate is a spectator ion, always, okay, always spectator ion. So it's the calcium hydroxide portion that we're interested in, right, the Ksp expression. We're going to do this one. It says, well, it gives us the concentration of CaNO32 is 0.10 molar. So if you recall, like we said, the NO3 is the spectator ion. So that's going to be the same as the initial concentration of Ca2+. Is everybody okay with that? Okay. If you're not okay with that, let's do another reaction equation, just to prove, okay. So this thing is soluble. So what is it going to go to? These, we have one of these. So for every 0.1 molar of this, we have 0.1 molar of that. Is that true too? Okay. So let's do a nice table. So here we're going to put 0.10 molar. Here, nothing here. So nothing here but plus s, remember, for solubility, plus s for solubility. How do you do this? Thank you. So here we're going to have 0.10 plus s, and here we're going to have 2s. So we can simplify this one by removing s, just because of the 5% rule. If you do 5% at the end, you can check and you'll see it's lower than 5%. So we're going to remove the s there, and so now we have that set. Okay, so let's plug into our equilibrium constant expression and see what s is. So the ksp is going to be the same as 6.5 times the same to the negative 6. Well, calcium, 0.10, and the hydroxide is 2s. Okay, so we're going to have n, the solubility I get, the negative 3. As you might imagine, when you add it to a solution with a common ion, the solubility will be lower than what it was without that common ion. So because of Lysiathlia's principle, it's going to be pushing the reaction the other way. Is everybody okay with thinking like that? Any questions about this one? Okay, wonderful.