Half-life Practice wrsday, April 21, 2022 15 Goal: to further understand how nuclear reactions progress and are measured. Warm Up: 1. If a radioactive isotope has a half life of 30.5 days, how much of a 1200g sample would remain after 61 days? 2. If the starting mass of a radioactive sample is 100 grams and the final mass is 25 grams after 14 days, what is the half life of the isotope? Practice: (1.5pts@) You must show your work to receive credit!! 1. Fr-220 has a half-life of 27 seconds. How 2. Cs-137 has a half-life of 30.2 years. How long long would it take for a 12 g sample to would it take for a 56 g sample to decrease to decrease to 0.75g? iLrist 3. N-16 has a half-life of 7.2 seconds. How . Co-60 has a half-life of 5.3 years. How long long would it take for a 25.6 g sample to would it take for a 150g sample to decrease to decrease to 0.2g? RN . Kr-85 has a half-life of 10.5 years. If your |6. [-131 has a half-life of 8 days. If your initial initial mass was 20 g, what would your final mass was 100 g, what would your final mass be mass be after 42 years? after 24 days? . P-32 has a half-life of 14.3 days. If your . Sr-90 has a half-life of 28.8 years. I your initial ~ |* initial mass was 16 g what would your final mass was 36 g what would your final mass be mass be after 42.9 days? (O W BT R TER . Your sample has an initial mass of 120 g and |10. Your sample has an initial mass of 240 ganda | |** a final mass of 15 g after 45 days. What is final mass of 7.5 g after 50 days. What is the the half-life of your isotope? half-life of your isotope? 11. Your sample has an initial mass of 1000 g [12. Your sample has an initial mass of 0.8 g and a and a final mass of approximately 15.6 g final mass of 0.05 g after 84 years. What is after 72 years. What is the half-life of your the half-life of your isotope? isotope? 11. Your sample has an initial mass of 1000 g 12. Your sample has an initial mass of 0.8 g and a and a final mass of approximately 15.6 g final mass of 0.05 g after 84 years. What is after 72 years. What is the half-life of your the half-life of your isotope? isotope? 13. Your sample had an initial mass of 24 g and 14. The mass of your sample is 12.5% of it's a final mass of 1.5 g after 36 months. What initial mass in 180 seconds. What is the half- is the half-life of your isotope? life of your isotope? 15. Your sample has decreased in mass to 25% 16. The mass of your sample is 6.25% of it's in 140 days. What is the half-life of your initial mass in 38 days. What is the half-life isotope? of your isotope? 17. If your final mass is 0.25 g and the half-life 18. If your final mass is 1.3 g and the half-life is is 3.5 seconds, what was the initial mass of 22 hours, what was the initial mass of the the sample after 10.5 seconds? sample after 132 hours? 19. If your final mass is 12g and the half-life is 20. If the half-life of Carbon 14 is 5,730 years, how 27 days, what was your starting mass after old is a log that is emitting 0.95625 beta 108 days? particles per g per min? (Living things emit 15.3 beta particles/g/min) Exit: If an isotope has a half-life of 30 years then what does that mean for the amount of radioactivity in the sample