At 65 days, it is (65, 54.32) Iridium-192 is one radioisotope used in brachyther

Question

At 65 days, it is (65, 54.32)

Iridium-192 is one radioisotope used in brachytherapy, in which a radioactive source is placed inside a patient's body to treat cancer. Brachytherapy allows the use of a higher than normal dose to be placed near the tumor while lowering the risk of damage to healthy tissue. Iridium-192 is often used in the head or breast. Answer the following three questions (a, b, and c) based on the radioactive decay curve of iridium-192, shown below. Click on the graph and move the mouse over a po to get values for that po . if the initial sample is 8.75 g, what mass of the original iridium-192 remains after 65 days? continued below... Estimate the half-life of the radioisotope. continued below... How many days would it take for one-third of the sample to decay?

Explanation / Answer

it is first order kinetics

From the given data

T1/2 = 70 days from the graph

K=0.693/T1/2 = 0.693/70 = 0.0099 days^-1

a) K=2.303/t log[a/a-x]

0.0099 = 2.303/65 log [ 8.75/a-x]

a-x = mass of Ir remaining = 4.6 gram

b)   T1/2 = 70 days from the graph

c)

K=2.303/t log[a/a-x]

t= 2.303/0.0099 log[8.75/1.4375]

= 182.47208685 Days

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