Posted by **Anonymous** on Wednesday, December 12, 2012 at 10:35pm.

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!

- Chemistry -
**TutorCat**, Wednesday, December 12, 2012 at 11:20pm
Every 14 seconds, the isotope's mass is halved.

- Chemistry -
**DrBob222**, Wednesday, December 12, 2012 at 11:42pm
You can iterate as TutorCat suggests, or you can follow this formula

k = 0.693/t_{1/2}

Solve for k and substitute it into the equation below.

ln(No/N) = kt

No = 32

N = 1

k from above.

solve for t.

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