Question

Q2. How long will it take for 98.6% of a sample of Au to decompose (t1/2 = 8.8 min)? Please write down the duration with a unit of min. Please round your answer to the whole number.

Answer 1

(1/2)^(t/8.8) = 0.14
t = 24.96

Answer 2

@oobleck---why are we not getting the same answer. I figure I screwed up.
k = 0.693/8.8 = 0.07875
ln(No/N) = kt
ln(100/100-98.6) = ln(100/1.4) = ln(71.43) = 0.07875t
4.27 = 0.07875t
t = 54.2 minutes