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Laboratory Experiment 2: Precision and Accuracy of Measurements Roberto DeVarona Partner: Alexa Graham 9/19/2016 I commit to uphold the ideals of honor and integrity by refusing to betray the trust bestowed upon me as a member of the Georgia Tech community.
Data and Results: A. Balance Use: Table 1. General Data from Part A Nominal mass of sweetener (g) 1 Mass of empty packet (g) 0.24 9 Number of single balance 1 Table 2. Variation in Mass Across Packets of Sweetener Packet No. Mass of Contents + Packet (g) Calculated Mass of Contents (g) Percent Error (%) 1 1.207 0.958 4.20 2 1.245 0.996 4.00 3 1.289 1.04 4.00 4 1.284 1.04 3.50 5 1.217 0.968 3.20 Mean (g): 0.999 Standard Deviation (g): 0.0306 1.207 .249 = .958 g | 1 .958 1 | = .0420 × 100 = 4.20 Table 3. Variation in Mass Across Balances Balance No. Mass of Contents + Packet (g) Calculated Mass of Contents (g) Percent Error (%) 1 1.288 1.04 0.0400 2 1.289 1.04 0.0400 3 1.285 1.04 0.0400 4 1.291 1.04 0.0400 Mean (g): 1.04 Standard Deviation (g): 0.00 1.288 .249 = 1.04 g | 1 1.04 1 | = . 0400 × 100 = 4.00
B. Measuring Liquids Table 4. Precision of Graduated Cylinders of Various Volumes Cylinder Size Smallest Graduation (ml) Estimated Precision (ml) 25 1 0.5 100 1 0.5 1000 Water Temperature (ºC): 23.5 Water Density (g/ml): 0.997 1 Table 5. Water Delivered by 10 ml Graduated Cylinder Nominal Volume of Water (ml) Mass of Beaker and Water (g) Mass of Water Delivered (g) Calculated Volume of Water Delivered (ml) 0 49.600 10 59.928 10.328 10.4 20 70.343 10.415 10.4 30 80.661 10.318 10.3 Mean (ml): 10.4 Standard Deviation (ml): 0.0437 59.928 49.600 = 10.328 g 10.328 ÷ .997 = 10.4 ml Table 6. Water Delivered by 10 ml Serological Pipet Nominal Volume of Water (ml) Mass of Beaker and Water (g) Mass of Water Delivered (g) Calculated Volume of Water Delivered (ml) 0 49.600 10 59.350 9.750 9.78 20 69.122 9.772 9.80 30 78.877 9.755 9.78 Mean (ml): 9.79 Standard Deviation (ml): 0.00818 59.350 49.600 = 9.750 g 9.750 ÷ .997 = .978 ml
Table 7. Water Delivered by 10 ml Volumetric Pipet Nominal Volume of Water (ml) Mass of Beaker and Water (g) Mass of Water Delivered (g) Calculated Volume of Water Delivered (ml) 0 49.600 10 59.544 9.944 9.97 20 69.972 10.428 10.5 30 79.375 9.403 9.43 Mean (ml): 9.95 Standard Deviation (ml): 0.420 59.544 49.600 = 9.944 g 9.944 ÷ .997 = 9.97 ml C. Quantitative Solution Making Table 8. Excel Formulas for Solution