0/2015 1155 PM 22.2/100 Gradeb - Print n 6 of 9 Ca ulator Periodic Table Map Iri
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0/2015 1155 PM 22.2/100 Gradeb - Print n 6 of 9 Ca ulator Periodic Table Map Iridium-192 is one radioisotope used in brachytherapy, in which a radioactive source is placed inside a Iridium-192 is one radiolsotope used in patient's body to treat cancer the tumor while lowering the risk of damage to healthy tissue. Iridium-192 is often used in the head or breast herapy allows the use of a higher than normal dose to be placed near Answe the toloatoe t el nsed on be mdochve decay.rnw olirdm-192. 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 paint Sample remaining (%) 100 90 70 80 10 Time (days) a) If the initial sample is 6.00 g, what mass of the original Iridium-192 remains after 130 days? Number
Explanation / Answer
a) from the graph
time taken to decay 50% of sample (t1/2) = 70 days
for 1st order reaction
k = 0.693/t1/2 = 0.693/70 = 0.0099 days^-1
k = 2.303/tlog(a/a-x)
a = initial conctntration = 6 g
a-x = concentration after 132 days = ?
t = 130 days
therefore,
0.0099 = (2.303/130)*log(6/a-x)
a-x= 1.657 grams
b ) T1/2 = 70 days
c)
0.0099 = (2.303/t)*log(1/(1/3))
t = 110.99 days
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