A sample of americium oxide, AmO₂, was prepared for use in a smoke detector, as described in the introduction to this chapter. The detector contains 0.000330 g Am-242 oxide , and the absolute disintegration rate is measured at 3.70 × 10⁷ disintegrations/s. Calculate the half-life of ²⁴¹Am, and express the answer in years.

Strategy Equation 21.1 relates the decay rate to the number of atoms present, which can be calculated from the mass of AmO₂ and Avogadro’s number.

Equation 21.1

Transcribed Image Text:

Rate = -AN At = kN