Performed calculations for the standard and the DO content can be seen in the

Performed calculations for the standard and the do

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Performed calculations for the standard and the DO content can be seen in the appendix. Conclusions and Recommendations The dissolved oxygen (DO) content of the water sample is calculated to be at 2.049 ppm and it can be concluded based on the results of the experiment that the body of water where the sample was taken theoretically cannot support life because it is highly polluted (See Table 1). Relative standard deviation is at 41.595 ppt and its confidence interval at 95% is 2.048631741 ± 0.211547453 . These results are however deemed anomalous since aquatic life do exist in the source of the water sample. It is hypothesized that the DO content of the sample was significantly altered by heterotrophic organisms present in the sample. The sample was stored for two days giving these organisms plenty of time to consume most of its DO content and thus leading to false results. Other than the consumption of oxygen, the deviation of the DO content can be caused by errors such as altering the correct order of the addition of reagents, inducing air bubbles during titration, or water used in the experiment is not boiled. To avoid such anomalous results in the future, it is best that the water sample must be subjected to Winkler titration immediately to avoid addition or reduction of DO content. The temperature of the sample should also be noted to better compare accepted DO content for water quality. Series of replications of the experiment is also recommended to give a precise data of the actual DO content in the water source. References Skoog, Douglas A., Donald M. West, and F. James. Holler. Fundamentals of analytical chemistry. 9th ed. Fort Worth: Saunders College Pub., 1996. Print. Petrucci, Ralph H. General chemistry: principles and modern applications. Toronto, Ont.: Pearson Canada, 2011. Print.
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R. J. C. De Guzman / Chemistry 26.1 (2017) P a g e | 4 Soden, JM. "The Winkler Titration Method." Sciencing. Leaf Group, n.d. Web. 28 Mar. 2017. Fondriest Environmental, Inc. “Measuring Dissolved Oxygen.” Fundamentals of Environmental Measurements. 7 Jan. 2014. Web. “Information about end point detection with starch in iodometric titration.” Iodometric titration - detection of end point witch starch, 22 Mar. 2014, Web. Clemente, Jamela Jirah L. “Redox Titration: Winkler Method for Dissolved Oxygen Content Determination.” Diliman, Quezon City, University of the Philippines, University of the Philippines, 2013. Rivera, R.Y.A. “Quantitative Determination of Dissolved Oxygen Content by Winkler Redox Titration.” University of the Philippines, University of the Philippines, 2015. Appendix A. Raw Data Table Standardization of Na2S2O3 Solution Primary Standard used: KIO3 Formula mass of 1 standard: 214 g/mol %Purity of 1 standard: 99.4 Weight of standard, g: 0.15 Volume of standard solution: 150 mL Trial 1 2 3 Volume of KIO3 Standard, mL 40 40 40 Final Volume Na2S2O3, mL 37.6 37.1 37.6 Initial volume Na2S2O3 0.6 0.1 0.6 Net volume of Na2S2O3 37.0 Average M Na2S2O3 0.0011298307 M Sample Analysis Location of sampling: Science Complex Park, Institute of Mathematics.
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