Chemistry
posted by Taylor .
The halflife of iodine 125 is 60 days. What fraction of iodine125 would be left after 180 days?
my teacher didn't teach us this and expects us to know it and I don't understand!!!
could you explain it please!?

The half life of a material is the time it takes for exactly 1/2 of the material you started with to disintegrate into another material. In this case, the half life is 60 days. Therefore, 1/2 will be left after 60 days, 1/2 of the 1/2 (that is 1/4) will be left after 120 days (a second half life) and 1/2 of the 1/4 (=1/8) will be left after 120 days (the third half life).
The amount left is 1/2^{n} where n is the number of half lives.
1/2^{n} = 1/2^{3} = 1/8
Respond to this Question
Similar Questions

science
the halflife of iodine131 is 8 days. how much iodine131 will be left after 8 days if you have an initial mass of 1g ? 
Math with science
Radioactive iodine treatment is so successful at treating hyperthyroidism that it has virtually replaced thyroid surgery. To the nearest full day, determine how long it will take for 400 millicuries of I131, which has a halflife … 
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 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
Iodine131 has a half life of eight days. What mass of iodine131 would remain from a 20g sample after 32 days? 
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? 
Chemistry
2. The halflife of a radioactive element is important when considering its application in medicine. For example, iodine131 is often used in the imaging of the thyroid. The reason is that iodine is readily absorbed by the thyroid … 
Chemistry. Half Life Problem. Help Plz
If the halflife of iodine131 is 8 day, how much would remain undecayed after 8 day if we started with 38 grams? 
science
A Geiger counter is used to measure the activity of a sample of iodine131. Based on the data, what is the halflife of iodine131? 
Math
the halflife of iodine131 is 8 days. how much iodine131 will be left After 35 grams sample after 32 days?