Asked by Anonymous

How to figure out half-lives

Half-live of Indium-116 is 14 seconds. How long will it take for 32 grams of this istotopw to decay to 1.0 grams. I know the answer is 70seconds but do not know how to get it!
Answered by TutorCat
Every 14 seconds, the isotope's mass is halved.

Answered by DrBob222
You can iterate as TutorCat suggests, or you can follow this formula
k = 0.693/t<sub>1/2</sub>
Solve for k and substitute it into the equation below.
ln(No/N) = kt
No = 32
N = 1
k from above.
solve for t.