Hard Water Ions
Abstract
In this experiment, a total of two solutions were prepared. In a 200 mL beaker, 3 mL of magnesium chloride, 5 mL of a buffer solution, 3 mL of the indicator Eriochrome Black T, and 50 mL of tap water were added inside the beaker. The solution was a reddish pink color. Then, using a burette, ethylenediaminetetraacetic acid (EDTA) was poured inside the burette. The acid was slowly added to the solution until it turned blue. It was recorded that it required 76.5 mL of EDTA for the solution to change from the reddish pink color to blue. In another 200 mL beaker, the same amount of the same substances (magnesium chloride, buffer solution, and Eriochrome Black T) was added inside the beaker. However, instead of adding 50 mL of tap water, 50 mL of deionized water was added to the solution. EDTA was again slowly added to the solution until the color changed from reddish pink to blue. After it turned blue, it was recorded that it required only 50 mL of EDTA for the…show more content… [1] Tap water is an example of hard water. In contrast, deionized water is water that has been filtered and went through the removal of the metal ions. The water thus becomes pure. [2] The main goal of this experiment was to compare tap water and deionized water regarding their hard water ions content. Magnesium chloride was used as a basic source for the hard water ions content. Since magnesium chloride is colorless, an indicator was necessary in order to reveal a color change to show how the moles of magnesium ions are converted into moles of ethylenediaminetetraacetic acid (EDTA), which is an acid that attaches to metals. [3] The indicator Eriochrome Black T was used in this experiment. Because of the fact that an acid was involved, a buffer solution was necessary in order to prevent drastic changes in the pH