Lab 2 Separating the Components of a Ternary Mixture Prop 375 (1).Pdf
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Course # Student name / Names of members of group Date: Exp # : Estimating the effects of acid rain Introduction: Precipitation that measures a pH value below 5.6 is generally considered as acid rain. Burning fossil fuels is the main reason for the elevated levels of gaseous oxides in a polluted atmosphere that in-turn forms acid rain. Gaseous oxides such as that of carbon, sulfur, nitrogen and phosphorus could dissolve in water to form an acidic solution. A generalized reaction sequence on the formation of acid rain is as follows;
One of the determinants of clean water in the natural environment is its alkalinity. Alkalinity can be defined as the capacity to neutralize acids. Carbonates (CO32-) are a major constituent in natural water that helps it behave as a buffer. Acid rain can reduce the alkalinity of water and hence would decrease its pH. In this experiment, water sources that measure pH below 5.6 will be considered acidic precipitation. Water from a variety of sources that receive precipitation is being sampled. Using a pH meter, the pH of water samples is being measured. In the first approach using titration methods in combination with pH measurement, the volumes of sulfuric acid needed for reaching two different pH levels are being measured. Difference in the volume of sulfuric acid used, is an equivalent for the amount of CaCO3 expressed in grams per (gL-1) in the analyte. Therefore the alkalinity of water samples is being calculated. In the second approach, the two volume readings for the respective amounts of sulfuric acid used are being determined an indicator based method. Congo red and bromocresol green are being used as the indicators. Procedure (Outline provided as pre-lab): A. The pH meter was calibrated using standard pH solutions provided. The pH electrode was washed with distilled water before being dipped in each solution in a small beaker.