In: Chemistry
Iodine - 131 is used in medical imaging. Iodine - 131 has a half-life of 8days. How much Iodine - 131 remains in a patient's system after 1 month?
The nuclear reactions are of first order reactions .
For a first order reaction rate constant , k = ( 2.303 /t )x log ( Mo / M)
Where
Mo = initial mass
M= Mass left after time t
t = time = 1 month = 30.4167 days
k = rate constant 0.693/t1/2 t1/2 = half life = 8 days
= 0.693 / 8
= 0.0866 day -1
Plug the values we get
log ( Mo / M) = (kt)/2.303
= ( 0.0866x30.4167) / 2.303
= 1.144
Mo / M = 101.144
= 13.9
M = Mo / 13.9
= 0.072 Mo
Therefore the mass of iodine -131 left in the patient is 0.072 times that of the initial mass