Chemistry
posted by TlP .
Suppose a patient is given 140mg of I−131, a beta emitter with a halflife of 8.0 days.
Assuming that none of the I−131 is eliminated from the person's body in the first 4.0 hours of treatment, what is the exposure (in Ci) during those first four hours?
Express your answer using two significant figures.

k = 0.693/t_{1/2}
k = approx 0.09 but you should get a more accurate number.
Convert 140 mg to number of atoms initially (at time = 0)
Use ln(No/N) = kt to determine N = number of atoms after four hours.
The difference between initial and after 4 hours is atoms that decayed in 4 hours.
Then 3.7E10 decays per second = 1 Ci 
that is wrong Ci does not equal 1

Read what I wrote. I said 3.7E10 dps = 1 Ci, not that Ci = 1.
Respond to this Question
Similar Questions

chemistry
Iodine131 is used to destroy thyroid tissue in the treatment of an overactive thyroid. the halflife of iodine131 is 8.02 days. if a hospital receives a shipment of 200.0g of iodine131, how much iodine131 would remain after 32 … 
Math please help!
Nuclear medicine technologists use the Iodine isotope I131, with a halflife of 8 days,to check thyroid function of patients. After ingesting a tablet containing the iodine, the isotopes collect in a patient's thyroid, and a special … 
Math
Please show me how to solve: Doctors can use radioactive iodine to treat some forms of cancer. The halflife of iodine  131 is 8 days. A patient receives a treatment of 12 millicuries of iodine  131. (A mullicurie is a unit of radioactivity.) … 
chemistry
The disintegration of a radioisotope, such as I131 to Xe131, is another example of a firstorder reaction. It has a halflife of 8.0 days. I131 > Xe131 + e If you start with 1.40 g I131, how many grams of I131 will be left … 
chemistry
The disintegration of a radioisotope, such as I131 to Xe131, is another example of a firstorder reaction. It has a halflife of 8.0 days. I131 > Xe131 + e If you start with 1.40 g I131, how many grams of I131 will be left … 
chemistry
Iodine131, a beta emitter, has a halflife of 8 days.How many grams of a 10.0g sample of iodine131 would remain after 56.0 days? 
Exponential Growth and Decay
Doctors use iodine131 to treat some forms of cancer. The halflife of iodine131 is 8 days. A patient receives a treatment of 12 millicuries. A millicurie is a unit of radioactivity. How much iodine131 remains in the patient 16 days … 
Chemistry
Suppose a patient is given 140mg of I−131, a beta emitter with a halflife of 8.0 days. Assuming that none of the I−131 is eliminated from the person's body in the first 4.0 hours of treatment, what is the exposure (in … 
Chemistry
Suppose a patient is given 140mg of I−131, a beta emitter with a halflife of 8.0 days. Assuming that none of the I−131 is eliminated from the person's body in the first 4.0 hours of treatment, what is the exposure (in … 
chemistry
The halflife of I131 is 8.00 days. If a medical treatment involves a dose of 400. mg of I131, how much of the isotope remains after 48 days?