Abstract for Experiment 5A

Abstract for Experiment 5A - form complexes. Magnesium...

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Abstract for Experiment 5A Water has a variety of minerals and electrolytes in it. Electrolytes feature ions like Ca2+ and Mg2+. If one wanted to determine how much of these metal cations were present in a sample of water, one would need to perform a complexometric titration. This type of titration features the formation of metal complexes which ultimately lead to an indicator color change end point from which the concentration of metal cations can be determined. This type of titration used EDTA as the titrant. EDTA is a chelating agent that forms complexes with metal cations. The EDTA concentration was first determined by titrating a known concentration of Ca2+. The EDTA solution was then used to titrate a sample of water to which calagmite indicator and a pH buffer solution was added. The pH of the water needed to be above 8 in order for the EDTA to
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Unformatted text preview: form complexes. Magnesium nitrate was also added to enhance the indicator color change. When the indicator turned the solution to a blue color, this marked the endpoint of the titration. From the volume of titrant added, one was able to calculate the concentration of metal ions present in solution. One series of titration just measured the calcium content in a water sample while the other series of titration measured the amount of calcium and magnesium present in solution. From this experiment it was found that in a pond water sample the amount of calcium present was about 171 +/- 6 ppm and the magnesium present was found to be about 39.7 +/- 5.5 ppm. From these results it was found that calcium is in a much higher concentration than magnesium in a natural water sample....
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