Repeat measurements were carried out with and without using the qualitative ammonia test and the results are summarized. Mean values for the experimentally determined percentage of copper in the original Copper Chloride Dihydrate(WSDTY) samples were calculated for both methods and uncertainties were determined for n = 10 at the 95% confidence interval. The average experimental percent copper obtained from using visual inspection of the reaction mixture to determine when the precipitation reaction should be stopped was 22% ± 2%, with the experimental values ranging from 19.16% to 26.98%. Whereas, the average percent copper obtained experimentally using the addition of ammonia as a qualitative test for the presence of copper in solution was 34% ± 2%, with the measurements ranging from 30.16% to 37.18%. Percent recovery values and ranges are reported as a percentage of the theoretical mass of copper in the initially weighed samples of CuCl2?2H2O.
Statistical tests were carried out on the measurements to compare the results from the two methods. An F-test was performed using the variances from each method and Fcalculated was determined to be 1.026. The details of the F-test are given. A t-test for two samples with equal variances performed on the two sets of data resulted in a tcalculated value of 9.58 compared to the tcritical two-tailed value of 3.20. The details of the t-test are given.
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