Analytical Chem istry - DePauw University

Chapter 7 Collecting and Preparing Samples34310. Engels and Ingamells reported the following results for the % w/w K 2 Oin a mixture of amphibolite and orthoclase. 240.247 0.300 0.236 0.258 0.304 0.3300.247 0.275 0.212 0.311 0.258 0.187Each of the 12 samples had a nominal weight of 0.1 g. Determine theapproximate value for K s and the mass of sample needed to achieve apercent relative standard deviation of 2%.11. The following data has been reported for the determination of KH 2 PO 4in a mixture of KH 2 PO 4 and NaCl. 25Nominal Mass (g) Actual Mass (g) % w/w KH 2 PO 40.10 0.1039 0.0850.1015 1.0780.1012 0.4130.1010 1.2480.1060 0.6540.0997 0.5070.25 0.2515 0.8470.2465 0.5980.2770 0.4310.2460 0.8420.2485 0.9640.2590 1.1780.50 0.5084 1.0090.4954 0.9470.5286 0.6180.5232 0.7440.4965 0.5720.4995 0.7091.00 1.027 0.6960.987 0.8430.991 0.5350.998 0.7500.997 0.7111.001 0.63924 Engels, J. C.; Ingamells, C. O. Geochim. Cosmochim. Acta 1970, 34, 1007–1017.25 Guy, R. D.; Ramaley, L.; Wentzell, P. D. J. Chem. Educ. 1998, 75, 1028–1033.