Homework Sourse125I decays via electron capture to form 125Te and is often
125I decays via electron capture to form 125Te and is often used for treatment of prostate cancer. It has a half-life of 59 days.
A) How many half-lives have transpired after 400. days?
B) How much on an initial 75 µCi sample would remain after 400. days?
Solution
A)
Half- life period = t1/2 = 59 days
total life period = 400 days
number of half lives = total life period/half life period
number of half lives = 400/59 = 6.78
B)
Initial amount = N0 = 75 micro Ci
Half- life period = t1/2 = 59 days
total life period = 400 days
number of half lives = total life period/half life period
number of half lives = 400/59 = 6.78
n= 6.78
Remainig amount= N= N0/2^n
N= 75/2^6.78 =75/ 109.90 = 0.68
Remaining amount = 0.68 micro Ci.
