21. Nuclear Chemistry
Rate of Radioactive Decay
3PRACTICE PROBLEM
You have to determine the age of an ancient fabric sample. You burn a small piece of fabric in excess O2, and pass the produced CO2 through slaked lime (Ca(OH)2) to produce a precipitate of CaCO3. The radioactivity of a 0.545 g sample of CaCO3 is 2.15×10−4 Bq. Given that the radioactivity of the sample is due to 14C which has a half-life of 5715 years and the radioactivity of recent samples is 15.3 disintegrations/min per gram carbon, how old is the fabric sample?
You have to determine the age of an ancient fabric sample. You burn a small piece of fabric in excess O2, and pass the produced CO2 through slaked lime (Ca(OH)2) to produce a precipitate of CaCO3. The radioactivity of a 0.545 g sample of CaCO3 is 2.15×10−4 Bq. Given that the radioactivity of the sample is due to 14C which has a half-life of 5715 years and the radioactivity of recent samples is 15.3 disintegrations/min per gram carbon, how old is the fabric sample?
ANSWERS OPTIONS
A
23900 years
B
28400 years
C
35900 years
D
15400 years