chemistry

A sample of
131
I was purified and then analyzed for iodine content. It was found that the
sample was 99.8% pure. 25 hours later the sample was tested again and it was found that the
sample was now just 78.2% pure. What is the half
-
life of
131
I?

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  1. ln(No/N) = kt
    No = 99.8
    N = 78.2
    k = solve for this
    t = 25 hours

    Then k = 0.693/t1/2
    Solve for t1/2
    You probably do better to write I-131.

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  2. Half-life of I-131 is 71.03hours

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