A 35 mg dose of iodine-131 with a half-life of 8 days is administered to a patient. How long will it take for the iodine to decay so that there are only about 2 mg remaining?

Question

Quizplus · Accepted Answer

To determine how long it will take for a 35 mg dose of iodine-131 to decay to about 2 mg, we can use the half-life formula. The half-life of iodine-131 is 8 days, meaning every 8 days, the amount of iodine-131 is reduced by half. Starting with 35 mg, we want to find how many half-lives it takes to get close to 2 mg:1st half-life (8 days): 35 mg / 2 = 17.5 mg2nd half-life (16 days): 17.5 mg / 2 = 8.75 mg3rd half-life (24 days): 8.75 mg / 2 = 4.375 mg4th half-life (32 days): 4.375 mg / 2 = 2.1875 mgAfter 4 half-lives, or 32 days, the amount of iodine-131 is approximately 2 mg.

A 35 Mg Dose of Iodine-131 with a Half-Life of 8