EDTA is a simple keywader that can be used in the analysis of many metals. In this case we're doing an analysis of calcium. The calcium samples are aquated into a flask and rinse down with dey water. For this analysis we'll be using Iriacrom Black T as the indicator. Like EDTA, Iriacrom Black T is a keywading agent, however this one has a color. For this titration to work it is crucial that the pH remain at around 10. For this reason we will either add buffer or ammonia to the solutions prior to the titrations. As you can see, when Iriacrom Black T complexes calcium, the color of the solution becomes perpoche red. Once all the calcium has been complex by EDTA, the Iriacrom Black T will revert to a blue color. As with all titrations, you should ideally swirl the flask as much as possible to ensure the reaction proceeds fully. You also want to rinse down the sides of the flask on occasion to make sure that no titrant or anylite is splittered up onto the edges of the flask. And of course prior to starting this titration we did measure the volume of titrant in the flask and ensure that there were no air bubbles in the tip beneath the stopcock. The color change in this titration is very subtle and very gradual. You will have to be paying close attention to the color of your solution over the course of the titration. You will note that your titration starts out as a reddish purple solution and gradually lightens in color becoming more and more blue. This video has been edited to try and show you the different levels of color that you will see throughout the titration, going from the very rich dark purpleish red at the beginning to the very light blue at the end. As you near the end point of your titration, you will notice that a blue solution does appear in the middle of your flask where titrant has been added prior to swirling. This obviously will disappear as you do swirl it. As that blue color becomes more persistent, go more slowly and add solution drop wise. The ideal end point for this titration is a color that has no red traces to it, of crisp blue. As you can see here, we have now reached a blue color without any traces of red or purple. You may wish to take a reading and add another drop and see if there is any significant change in color. As you can see here, there is no evident change, therefore the first drop that we added was the correct endpoint. For comparison purposes, here is an overshot endpoint and the initial color of the solution.