Honors Chem - 1231 Words

Directions: The following questions involve more practice with radioactive decay half-life. Complete the problems to the best of your ability. This assignment is due by next WEDNESDAY, November 16th. 1. If 100.0 g of carbon-14 decays until only 25.0 g of carbon is left after 11 460 y, what is the half-life of carbon-14? a. Calculate how many half-lives have passed during the decay of the 100.0 g sample. 100 grams/2 50 grams/2 25grams†¦2 half lives have passed b. Solve for the half-life. 11,460year/2 half lives = 5,730 years half-life of carbon – 14 2. What is the half-life of a 100.0 g sample of nitrogen-16 that decays to 12.5 g of nitrogen-16 in 21.6 s? 100g50g25g12.5g†¦3 half lives have passed 21.6s/3 half†¦show more content†¦150days/30days = 5 half lives have passed 200mg/2 100mg/2 50mg/2 25mg/2 12.5mg/2 6.25mg of polonium – 210 remain 16. A 1000 gram sample of Titanium-50 decays to 62.5 grams in 2000 years. What is the half-life of Titanium-50? 1000g/2 500g/2 250g/2 125g/2 62.5g †¦ 4 half lives have passed 2000years/4 half lives = 500years half-life of Titanium – 50 17. The half-life of Potassium-44 is 10 days. If after 50 days you end up with 15 grams of Potassium-44, how many grams did you start with? 50days/10days = 5 half lives have passed WORKING BACKWARDS in time†¦ 15g x 2 30g x 2 60g x 2 120g x 2 240g x 2 480g †¦amount of potassium – 44 you started with 18. The half life of Carbon-14 is 5730 years. A scientist finds a 17190 year old fossil of a bumble bee. A live bumble bee of this kind has 600 million atoms of Carbon-14. How many atoms of Carbon-14 are in this fossil? 17,190years/5,730years = 3 half lives have passed 600 million atoms/2 300 million atoms/2 150 million atoms/2 75 million atoms of carbon – 14 are found in this fossil 19. The half life of Polonium-210 is 140 days. How many milligrams of polonium-210 remain after 420 days if you start with 20 milligrams? 420days/140days = 3 half lives 20mg/2 10mg/2 5mg/2 2.5 mg of polonium – 210 remain after 420 days 20. A 600 gram sample of Nitrogen-18 decays to 75 grams in 750 seconds. What is the half-life ofShow MoreRelatedWhy I Am A Better Nigeria?1562 Words   |  7 Pagesnot just declaring a major in whatever department but making an informed decision on what they want to study and do with the rest of their life. While majoring in general engineering, we are expected to take some specific courses; MATH 1225, CHEM 1035, CHEM 1045, ENGL 1105, PHYS 2305, and ENGE 1105 (the actual foundation to engineering class). 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