# Problem: Americium-241 is used in smoke detectors. It has a first order rate constant for radioactive decay of k = 1.6 10–3 yr–1. By contrast, iodine-125, which is used to test for thyroid functioning, has a rate constant for radioactive decay of k = 0.011 day–1.What is the half-life of iodine-125?

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###### FREE Expert Solution

Recall that half-life is the time needed for the amount of a reactant to decrease by 50% or one-half

The half-life of a first-order reaction is given by:

where:

t1/2 = half-life

k = decay constant

###### Problem Details

Americium-241 is used in smoke detectors. It has a first order rate constant for radioactive decay of k = 1.6 10–3 yr–1. By contrast, iodine-125, which is used to test for thyroid functioning, has a rate constant for radioactive decay of k = 0.011 day–1.

What is the half-life of iodine-125?