410
Nuclear Chemistry
amounts of A and B in a given ore sample that has lain undisturbed and
unprocessed since its creation
17 Show your reasoning.
24. A 100 ml sample of a 0.0100 M Ba(NO 3 ) 2 solution is mixed with 100 ml of a
0.0100 M Na 2 SO 4 solution that has been labeled with ?|S and that has 25,000
cpm/ml of solution. After precipitation, the supernatant liquid is filtered off,
and it is found that 1.00 ml of solution now has only 26.0 cpm (corrected for
background). From these data, calculate the solubility product for BaSO 4 .
25. It is a common experience when working with radioactive materials that a
sample under investigation contains two or more radioisotopes. Assume that
you have a sample with just two radioisotopes, one with a half-life about 10
times that of the other. The amounts of the two in the sample are too small to
separate chemically.
(a) How could you study the sample so as to determine the half-lives of the
two isotopes?
(b) Apply your method to the accompanying data, which were taken from
such a sample. The cpm values have been corrected for background. The
times in minutes are followed by cpm in parentheses: 0 (3160), 2 (2512), 4
(2085), 6 (1512), 8(1147), 10(834), 12(603). 14(519), 17 (457), 20 (407), 25
(388), 30 (346), 40 (327), 50 (320), 60 (308), 70 (288), 80 (282), 90 (269), 105
(269), 120 (240), 135 (228), 150 (229), 165 (214).
26. Solve Problems 15, 16, 17, and 18 on p 250.
Nuclear Chemistry
amounts of A and B in a given ore sample that has lain undisturbed and
unprocessed since its creation
17 Show your reasoning.
24. A 100 ml sample of a 0.0100 M Ba(NO 3 ) 2 solution is mixed with 100 ml of a
0.0100 M Na 2 SO 4 solution that has been labeled with ?|S and that has 25,000
cpm/ml of solution. After precipitation, the supernatant liquid is filtered off,
and it is found that 1.00 ml of solution now has only 26.0 cpm (corrected for
background). From these data, calculate the solubility product for BaSO 4 .
25. It is a common experience when working with radioactive materials that a
sample under investigation contains two or more radioisotopes. Assume that
you have a sample with just two radioisotopes, one with a half-life about 10
times that of the other. The amounts of the two in the sample are too small to
separate chemically.
(a) How could you study the sample so as to determine the half-lives of the
two isotopes?
(b) Apply your method to the accompanying data, which were taken from
such a sample. The cpm values have been corrected for background. The
times in minutes are followed by cpm in parentheses: 0 (3160), 2 (2512), 4
(2085), 6 (1512), 8(1147), 10(834), 12(603). 14(519), 17 (457), 20 (407), 25
(388), 30 (346), 40 (327), 50 (320), 60 (308), 70 (288), 80 (282), 90 (269), 105
(269), 120 (240), 135 (228), 150 (229), 165 (214).
26. Solve Problems 15, 16, 17, and 18 on p 250.