Question

1. "Au (TI/2 = 64.8 hr) can be produced by bombarding stable 197 Au with neutrons in a nuclear reactor. Suppose that a Au foil weighing 0.1 g is placed in a certain reactor for 1 2 hrs and that its activity is 0.90 Ci when removed. (a) What is the theoretical maximum activity due to "Au in the foil? (b) How long does it take for the activity to reach 80% of the maximum?

Answer 1

its Otis fiost order geaction, so half life, Ty2 = 64.8hr sate constant (a)= Ouma = 1:07 X10-2 /ho - A= Ao ext +R(1-ent) where R. is maximum activity 0.9 Ci = 0 + R Cicé la - R=7.47ci b) Activity 80% of maximum A=0.8R 0.8 R=RCI-e-At) - eit= o.8 eta 0.2 -at = ln (0.2) -1.07X10 X12 R=7.47Ci t = 150.49 has