[Music] Hello! My name is Dr. Eszter Trufan and in this video I'm going to demonstrate how to record the pH, and from there you can calculate the pOH, of a calcium hydroxide solution. So earlier we prepared a saturated calcium hydroxide solution, and we confirmed through the Tyndall effect that it was indeed a solution, and no longer a heterogeneous mixture. Now we move on to the next step! Let's determine how much of the calcium hydroxide is truly dissolved, and we can go about it either by determining the calcium ion concentration or the hydroxide ion concentration. It is easier to determine the hydroxide ion concentration by a pH probe. So for today's experiment, we're going to need a pH probe that is wirelessly connected to a device, and I will be using a phone. Then we are going to need the calcium hydroxide solution that we previously prepared. We will need a squeeze bottle, with deionized water, some Kimwipes, a waste bottle and a small beaker to contain our saturated calcium hydroxide solution. So the first thing I'm going to do is transfer some of my calcium hydroxide solution into the small beaker. I already calibrated my pH probe, so I'm simply going to open it up, extract my pH probe, rinse it thoroughly with deionized water, wipe it with the Kimwipes, and I want to be very gentle with it, and then I will slide it slowly and carefully into my calcium hydroxide saturated solution. And from there, I am going to record the pH of the solution. I can move it around a little bit, I simply have to be very careful. The pH is moving just a little bit and currently, it is reading 12.45. And that is it for our experiment. Before we move on to any further pH measurements, we need to rinse off our pH probe, wipe it off, and return it to its buffer solution. [Music] [Music] [Music] [Music]