By the way, in the previous example, we set the initial number of 14C atoms to 2.61 x 1011. With this number, one 14C atom will β-decay in exactly one second. We know that only 1.2 x 10-12 (about one trillionth) of the carbon in the atmosphere is 14C. This means that if there are 2.61 x 1011/(1.2 x 10-12) (= 2.175 x 1023) carbon atoms in the atmosphere (total of 12C, 13C, and 14C), one 14C atom will β-decay in one second. This total number of carbon (2.175 x 1023) is 0.36 moles of carbon atoms. This is equivalent to the amount of carbon dioxide (400 ppm) in 20 m3 of air. If the classroom is 10 m x 10 m x 3 m, then 15 β-decays are occurring per second in the air of that classroom. In the human body, which is a mass of carbon, each person (weighing about 75 kg) has approximately 4,000 β-decays per second. This is a surprisingly familiar phenomenon.

Last modified: Wednesday, 19 July 2023, 6:45 PM