Sodium-24 has a half-life of 15.0 hours. A sample of sodium-24 with an initial mass of 22.5g was stored for 45.0 hours.

Question

how many grams of sodium-24 is left in the sample after 45.0 hours?

Answer 1

A(t) = A₀(1/2)^t/15.0, t in hours, A in grams

 

A(45.0) = 22.5 (0.5)^45/15.0 ≅ 2.81 g