JOSE ROMUALDO D. VINARAO
Institute of Chemistry, University of the Philippines, Diliman Quezon City
Date Performed: July 4, 2013
Date Submitted: July 10, 2013
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METHODOLOGY In a gravimetric analysis, the determination is carried out by converting the analyte into an insoluble substance which is isolated and weighed1. In this experiment we used precipitation gravimetry from which the analyte is separated from a solution of the sample as a precipitate and is converted to a compound of known composition that can be weighed2.
RESULTS AND DISCUSSION Data Sheet 2 | Coins | Mass | 1 | 3.5688 | 2 | 3.5808 | 3 | 3.6041 | 4 | 3.6083 | 5 | 3.6460 | 6 | 3.6516 | Total | 21.6596 | Mean | 3.6099 | Table 1 Table 2 Data Sheet 1 | Coins | Mass | 1 | 3.5340 | 2 | 3.5650 | 3 | 3.5689 | 4 | 3.5807 | 5 | 3.5886 | 6 | 3.5917 | 7 | 3.6042 | 8 | 3.6082 | 9 | 3.6460 | 10 | 3.6516 | Total | 35.9389 | Mean | 3.59389 | Theoretical | 3.6000 |
The ten 25 centavo coins sample were chosen due to availability at the moment of experiment. The weight of the coins were taken using “weighing by difference method” to have a faster and more stable result of mass. We thought that they should have almost the same mass since they are made by same set of machine. The results were not far from the theoretical value but it is not close enough to consider as same weight to each other since same weight should have a weight difference of 0.0002 grams. Although some coins have a big difference to the theoretical value, the computed mean value 3.5939 and 3.6099 is very close to the theoretical value 3.6000 which yielded a satisfying result of 0.1694 % and 0.275 % error for data sheets 1 and 2. Possible errors for this experiment resulted to the choice of coin. Some of our coins have dirt attached to it and some