Posted by **cam** on Monday, April 11, 2011 at 7:07pm.

caffeine has a half-life of 4.6 hours in the human body.. How long would it take 125 milligrams tritium to decay to 22 milligrams?

- chemistry -
**DrBob222**, Monday, April 11, 2011 at 10:49pm
Pray tell what does caffeine have to do with tritium?

For tritium,

k = 0.693/t_{1/2}

You will need to look up the half-life of tritium unless that is the "caffeine" half-life.

Substitute k into the below equation.

ln(No/N) = kt

Nl = 125

N = 22

k = from above calculation.

t = time. Solve for this. Note that the unit for time and the unit for half-life must be the same.

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