Lab 6: Determination of Water Hardness Using a Titrator

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Lab 6: Determination of Water Hardness using a Titrator Name: Brendan Lee Lab Partners: None Date of Experiment: 7/21/11 Location: My house Course Number: CHE 111 Abstract: The objective of this experiment was to develop familiarity with the concept of water hardness, practice titration using a titrator, and to determine the hardness of the local water supply. This will be done mainly by using EDTA (ethylenediamenetetraacetic acid) to test the indicator and titrating water with it. The amount of water (and therefore the amount of calcium and magnesium ions) needed to set off the indicator will be used to calculate the hardness of the water. Experiment/Observations: There are three parts involved in this experiment. The first part involved testing the indicator. This was done by preparing a buffer solution, dipping a few grains of EBT powder into the solution, and checking to ensure that the resulting solution turned a bright, clear blue. The second part involved actually performing the titration. In this step, I simply constructed a mechanism that would hold the titrator and I dripped a few drops of EDTA solution from the titrator into the beaker. Finally, the last step involved titrating the water. The tap water and buffer solution were poured into the beaker, and the EDTA solution was titrated into the beaker. A drop of EDTA was added every 5 seconds, and this continued until the solution turned the same light blue as observed in the first step of the experiment. The amount of EDTA needed was then used to calculate the hardness of the water sample. This whole process was repeated two times for two additional trials. Observations table | Initial EDTA Volume (mL) | Final EDTA Volume (mL) | Volume of EDTA used (mL) | Trial 1 | 10 | 10.48 | 0.48 | Trial 2 | 10 | 10.45 | 0.45 | Trial 3 | 10 | 10.50 | 0.50 | | Average volume of EDTA

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