[Music] Hello! My name is Dr. Eszter Trufan and in this video I'm going to demonstrate a method by which we can determine the hydroxide ion concentration of our saturated calcium hydroxide solution. For that, we're going to utilize our saturated calcium hydroxide solution that we previously prepared. We're also going to need a burette that is charged with our approximately 0.05 molar KHP solution. For us, that means that we're going to use a stand, a burette clamp, a burette and we follow the appropriate procedure for the cleaning and the charging of the burette, making sure that our charging liquid is our KHP solution. Next, as for every titration, we're going to use an Erlenmeyer flask and an indicator. For our indicator, we're going to use phenolphthalein, today. We want to know the exact volume of the saturated calcium hydroxide solution that we will be titrating, so we are going to need a 50 milliliter graduated cylinder. So let's get started! First, we're going to measure approximately 20 milliliters of the saturated calcium hydroxide solution. We are very close, so I'm going to stop here. We have 19.9 milliliters of the calcium hydroxide saturated solution. We set our solution to the side, then we transfer the solution into the Erlenmeyer. We add one to two drops of phenolphthalein, and that will give us a very vibrant fuchsia color. Before we begin the titration, we need to know the initial volume of the KHP solution in the burette, so we're going to bring the meniscus of our solution to our eye level and then we're going to read it. We have 2.20 milliliters as our first volume measurement. Then we push our burette to the top and oriented it in such a way that our hands are appropriately utilized. For me, that means that I am going to swirl the Erlenmeyer with my right hand and I am going to adjust the valve with my left. I want to raise it just a little bit higher, and we're going to stop with the addition of the KHP solution when our fuchsia colored becomes very faint or at the first sign of the color disappearing. And it turned clear. This is where we are going to record our endpoint. And our endpoint today is 29.23 milliliters. With that, because we know the volume of the KHP solution that we utilized for the titration, we know the concentration of the KHP solution because we prepared it, and we know the exact amount of KHP that was added to the solution, we should be able to determine the hydroxide ion concentration from the saturated calcium hydroxide solution. From the hydroxide ion concentration, then we can determine the calcium hydroxide concentration, and we can also determine the KSP value of the calcium hydroxide. [Music] [Music] [Music]