HW 21 Activities and Due Dates College , CHEM 1 120-Spring16-ESTES Gra /23/2016
ID: 989981 • Letter: H
Question
HW 21 Activities and Due Dates College , CHEM 1 120-Spring16-ESTES Gra /23/2016 10-10 AM 9 26.7/1004/27/2016 10:26 AM 26.7/100 3 4/2/206 /29/2016 10:10 AM Print Caculator -Porodic Table estion 8 of 30 Map Iridium-192 is one radioisotope used in brachytherapy, in which a radioactive source is placed inside a patients body to treat cancer. Brachytherapy allows the use of a higher than normal dose tobe placed near bu wing the risk of damag Iidium- 192 is ofen 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 point to get values for that point. click to edit Sample remaining (%) 100 70 9 5A 30 0 10 20 30 40 50 60 70 80 90 100 110 120 120 140 110160 170 180190 200 Time (days) a) If the initial sample is 3.00 g, what mass of the original inidium-192 remains after 35 days? Number continued below O Previous 'SveUp & Vow Soution check Answer Next Exit Im Cortana. Ask me anythingExplanation / Answer
From the graph for 50% of decay it is observed that 70 days are required.
so half life t1/2 = 70 days.
t1/2 = 0.693/K
K = 0.639 / 70 = 0.0099
K = 2.303 / t log(a/(a-x))
0.0099 = 2.303/35 log (3/(a-x))
(a-x) = 2.1216 g is remainig
for 1/3 of decay,
t = 2.303 / 0.0099 log (100/(100-(100/3)))
t = 40.963 days
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