An original sample of the radioisotope fluorine-21 had a mass
Spencer Lutz 2022-05-10Answered
An original sample of the radioisotope fluorine-21 had a mass of 80.0 milligrams. Only 20.0 milligrams of this original sample remain unchanged after 8.32 seconds. What is the half life of fluorine-21?
You are starting with 80.0 mg of F-21. After 1 half-life, you will have 40.0 mg of F-21. After 2 half-lives, you will have 20.0 mg of F-21. Hence, 2 half-lives=8.32 s. 1 half-life = 4.16 s.