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Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Half-Life The _________ is the time required for half of a sample.

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Presentation on theme: "Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Half-Life The _________ is the time required for half of a sample."— Presentation transcript:

1 Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Half-Life The _________ is the time required for half of a sample of a radioactive substance to disintegrate by radioactive decay The half-life of a radioactive isotope is a ___________ and is not influenced by any external conditions, such as temperature and pressure. Section 3 Uses of Nuclear Chemistry Chapter 18

2 Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Half-Life Radioisotope Half-life Bismuth min Polonium sec Carbon yrs Polonium sec Chlorine yrs Radium yrs Cobalt yrs Sodium hrs Iodine days Strontium yrs Iron days Uranium mill yrs Phosphorus days Uranium bill yrs Chapter 18 Section 3 Uses of Nuclear Chemistry

3 Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Half-Life Example Problem: 212 Bi Po If you start with 200 g, how much is left after min? Answer: The half-life of bismuth-212 is ___________. How much is left after one half-life (60.5 minutes)? How much is left after 2 half-lives (121 minutes)? How much is left after 3 half-lives (181.5 minutes)? Chapter 18 Section 3 Uses of Nuclear Chemistry

4 Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Half-Life Practice Problem: Radium-226 undergoes alpha decay. (A)Write the transmutation equation for this change. (B)What is the name if the new substance that is produced? (C)If you start with 4000 g, how much will be left after 6408 years? Answers: (A) (B) Radon-222 Chapter 18 Section 3 Uses of Nuclear Chemistry 226 Ra Rn 86

5 Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Half-Life Practice Problem (continued): Radium-226 undergoes alpha decay. (C) If you start with 4000 g, how much will be left after 6408 years? Answer: What is the half-life of Radium-226? How much is left after 1 half-life? How much is left after 2 half-lives (3204 years)? How much is left after 3 half-lives (4806 years)? How much is left after 4 half-lives (6408 years)? Chapter 18 Section 3 Uses of Nuclear Chemistry 1602 years 2000 g 1000 g 500 g 250 g

6 Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Half-Life Practice Problem: Carbon-14 undergoes beta decay. (A)Write the transmutation equation for this change. (B)What is the name if the new substance that is produced? (C)If you start with 600 g, how much will be left after 17,790 years? Answers: 14 C N 7 (A) (B)Nitrogen-14 Chapter 18 Section 3 Uses of Nuclear Chemistry

7 Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Half-Life Practice Problem (continued): Carbon-14 undergoes beta decay. (C) If you start with 600 g, how much will be left after 17,790 years? Answer: What is the half-life of carbon-14? How much is left after 1 half-life? How much is left after 2 half-lives (11,860 years)? How much is left after 3 half-lives (17,790 years)? 5930 years 300 g 150 g 75 g Chapter 18 Section 3 Uses of Nuclear Chemistry


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