Half Life Worksheet Extra Practice ) Fluorie- has a half life of approximately 5 secods. What fractio of the origial uclei would remai after miute? ) Iodie-3 has a half life of 8 days. What fractio of the origial sample would remai at the ed of 3 days? 3) The half-life of chromium-5 is 8 days. If the sample cotaied 50 grams, how much chromium would remai after 56 days? How much would remai after year? How much was preset 68 days ago? 4) If 0.0 g of a radioactive isotope are preset at :00 PM ad 5.0 g remai at :00 PM, what is the half life of the isotope? 5) The half life of Uraium-38 is 4.5 billio years ad the age of earth is 4.5 X 0 9 years. What fractio of Uraium-38 that was preset whe Earth was formed still remais? 6) Chromium-48 decays. After 6 half-lives, what fractio of the origial uclei would remai? 7) The half life of iodie-5 is 60 days. What fractio of iodie-5 uclides would be left after 360 days? 8) Titaium-5 decays with a half life of 6 miutes. What fractio of titaium would remai after oe hour? 9) A medical istitutio requests g of bismuth-4, which has a half life of 0 mi. How may grams of bismuth-4 must be prepared if the shippig time is h? 0) The half life of radium 6 is 60 years. If you have 500 grams of radium today how may grams would have bee preset 96 years ago? ) U 38 has a half life of 4.46 billio years. How much U 38 was preset iitially if grams remais after 3.4 billio years? ) How much U 38 should be preset i a sample that is oly billio years old if 4 grams was preset iitially?
Half Life Worksheet Extra Practice: Solutios ) Fluorie- has a half life of approximately 5 secods. What fractio of the origial uclei would remai after miute? umber of half lives. If each half life is 5 secods, the i oe miute (60 secods) there are half lives. Therefore the aswer is: 4096 ) Iodie-3 has a half life of 8 days. What fractio of the origial sample would remai at the ed of 3 days? Usig the same fractio, you must figure out. If the half life is 8 days, the i 3 days, there are 4 half lives. Therefore the aswer is: 4 3) The half-life of chromium-5 is 8 days. If the sample cotaied 50 grams, how much chromium would remai after 56 days? How much would remai after year? How much was preset 68 days ago? I this problem, the fractio will be multiplied by the iitial amout. I the first problem each half life is 8 days, therefore i 56 days two half lives occur. This meas that =. The solutio is as follows: (Iitial amout) (50g) 7.5g The secod is solved the same way except that there are 3 half lives over oe year. This meas =3. The solutio is as follows: ( Iitail amout) (50g) 0. 06g 3
The third is solved by recogizig there must be more of the sample 68 days ago the there is ow. 68 days represets 3 half lives so =3. The solutio is: (Iitial amout) Fial amout Iitial amout Fial amout Iitial amout 500g 6 3000g 3kg 4) If 0.0 g of a radioactive isotope are preset at :00 PM ad 5.0 g remai at :00 PM, what is the half life of the isotope? I this problem, you must figure out how may half lives have occurred. After oe half life 0.0g becomes 0.0g. After a secod half life, 0.0g becomes 5.0g. This meas that durig the questio, two half lives have occurred. Sice this happeed over the course of hour, the each half life must be equal to: 30 miutes. 5) The half life of Uraium-38 is 4.5 billio years ad the age of earth is 4.5 X 0 9 years. What fractio of Uraium-38 that was preset whe Earth was formed still remais? 4.5 billio is exactly the same as 4.5 x 09. Therefore, the age of the Earth is equal to oe half life of Uraium. This meas that =. The solutio is a follows: 6) Chromium-48 decays. After 6 half-lives, what fractio of the origial uclei would remai? umber of half lives. If there are 6 half lives, the =6.Therefore the aswer is: 6
7) The half life of iodie-5 is 60 days. What fractio of iodie-5 uclides would be left after 360 days? umber of half lives. If each half life is 60 days, the i 360 days there are 6 half lives. Therefore the aswer is: 6 8) Titaium-5 decays with a half life of 6 miutes. What fractio of titaium would remai after oe hour? umber of half lives. If each half life is 6 miutes, the i hour (60 miutes) there are 0 half lives. Therefore the aswer is: 0 04 9) A medical istitutio requests g of bismuth-4, which has a half life of 0 mi. How may grams of bismuth-4 must be prepared if the shippig time is h? I this problem you must figure out the iitial amout. If you use the same set up as questio 3, the you ca solve for the iitial amout. You just have to figure out. If each half life is 0 miutes, ad hours (0 miutes) go by, the =6. The set up is as follows: ( Iitail amout) ( x) g 6 Solvig for x, x = g. 0) The half life of radium 6 is 60 years. What fractio of a sample radium-6 would remai after 96 years? If each half life is 60 years, the i 96 years there are 6 half lives. Therefore the aswer is: (Iitial amout) Fial amout Iitial amout Fial amout Iitial amout 500g 6 3000g 3kg
) U 38 has a half life of 4.46 billio years. How much U 38 was preset iitially if gra ms remais after 3.4 billio years? 3 half-lives have passed, so we take the fial amout ad double it 3 times (g x x x ). The fial aswer is 6. ) How much U 38 should be preset i a sample that is oly billio years old if 4 grams was preset iitially? This problem eeds to be solved usig the equatio: æ ö N(t) = N 0 è ç ø I this problem, we are solvig for the fial amout of radioactive uraium, N(t). The gives are: N o = 4 grams t = billio years t / = 4.46 billio years Substitutig ad solvig gets.9 grams as the fial aswer. t t