Could someone explain the theory behind the question. Why is it that you can relate ionic product to the calcium hydroxide, even if you dissociate calcium hydroxide to Ca2+ and 2(OH)- I don't see why you can use ionic product of water
instead of using Ionic product of water I assume you can use [OH-] = 0.0131 Then use 14+log(0.0131) to calculate the pH. I don't know how you could use the ionic product in this situation but I might be wrong