In addition, note that the question asked for the amount that decayed, not the amount that remaning. Note that the length of the half-life played no role in this calculation.
How many grams of a 10.0 gram sample would have decayed after exactly three half-lives? Problem #3: Os-182 has a half-life of 21.5 hours. (1/2) 5.56 = 0.0213 (the decimal fraction remaining after 5.56 half-lives) If one had 6.02 x 10 23 atoms at the start, how many atoms would be present after 20.0 days? Problem #2: Pd-100 has a half-life of 3.6 days.
(1/2) 3 = 0.125 (the amount remaining after 3 half-lives) If one had 100.0 g at the beginning, how many grams would be left after 7.2 minutes has elapsed? Problem #1: The half-life of Zn-71 is 2.4 minutes. ChemTeam: Half-Life Problems #1 - 10 Half-Life Problems #1 - 10 Ten Examples Problems involving carbon-14 Probs 11-25 Problems involving uranium-238 Probs 26-40 Examples and Problems only (no solutions) Return to Radioactivity menu
