Question

The first-order decay of radon has a half-life of 3.823 days. How many grams of radon remain after 7.22 days if the sample initially weighs 250.0 grams?

Answer 1

substitute: t1/2=ln(2)k→k=ln(2)t1/2 Into the appropriate equation: [A]t=[A]0∗e−kt [A]t=[A]0∗e−ln(2)t1/2t [A]t=(250.0 g)∗e−ln(2)3.823 days(7.22 days)=67.52 g