The Chemistry Of Natural Waters Lab Report

Grace Lowe
Chem 113-002
24 February 2023

Experiment 10: The Chemistry of Natural Waters
Introduction
The idea behind this experiment begins with a podcast that discusses how water tastes different, and the co-hosts tasted different waters to see if they could identify what company they came from¹. Instead of identifying the water based on taste, is it possible to identify water based on their hardness and mineral content? This experiment tries to answer that question. Through multiple chemical experiments, the mineral content and water hardness of each unknown sample was found to see if it is possible to identify the different waters.
Water hardness is a measurement of the amount of dissolved minerals present in that water². These minerals

According to the experimental results, the unknown water sample D4 had a calcium concentration of 34.9 ppm, a magnesium concentration of 40.3 ppm, a total hardness value from AA of 236, an average total dissolved solids value of 225, and an average hardness from EDTA value of 489 (see table 3). While the other two samples had low hardness values, this one has a large value, meaning it came from a European-sourced company. This hardness is very high compared to the water quality report values for any of the European values, however the experimental range is 283-695 when including standard deviation. The high standard deviation comes from the fact that a single-well EDTA titration was necessary to determine the hardness, and a single-well is less accurate than a serial because you cannot see each step next to one another, so it might be harder to notice when the endpoint is reached. According to their water quality reports, Evian has a hardness of 310 ppm⁹, and Perrier has a hardness of 390 ppm¹⁰. Both fall within the experimental range, but Evian is closer to the calculated value of 489 ppm. The next thing to compare is total dissolved solids. The experimental value is closer to Evian at 340 ppm⁹ while Perrier is higher at 440 ppm¹⁰. The final element to consider is calcium and magnesium concentrations. Evian has a calcium concentration of 82 ppm and a magnesium concentration of 26 ppm⁹. Perrier has

On the water quality reports, these values were overall different for each water company, so it was easy to narrow down the unknown sample’s identity by comparing numbers across all of these categories. The least helpful method was total dissolved solids because, when trying to distinguish between the two American companies, the ranges were very close and were not helpful in determining which company the water came from.

Conclusion
After completing an EDTA titration, atomic absorption spectrometry, and taking conductivity measurements, the calcium and magnesium concentrations, total dissolved solids, and total hardness of the unknown water samples were compared with known values from water quality reports in order to identify from which brand the sample came from. It was determined that sample A4 was from Poland Spring, B4 was from Deer Park, and D4 was from Evian. This experiment shows that water from different companies is different and that they can be identified based on their numbers given in the water quality reports.

References
¹ Graber, C.; Twilley, N. The Bottle vs. Tap Battle Finale: Alkaline H2O, Lead Pipes, and,