L42S07_ Radiochem_Nuclides-2 05-02-07

L42S07_ Radiochem_Nuclides-2 05-02-07 - CHEM 1A

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Unformatted text preview: CHEM 1A L42:"RadiochemPrinciples" Summary neutrons 160 Actinides 202 The Nuclides Zone of Stability (neutron : proton) 140 120 100 decay region - (1.5:1) 80 Hg ratio 80 110 48 60 (1.3:1) Cd (1:1) 56 40 26 20 6 3 0 20 Fe decay region + stable light nuclei (1:1) (1.5:1) stable heavy nuclei (1.2:1) Li (1:1) 40 2004 M.Kubinec, H. Nitsche protons 60 80 100 nuclear `magic numbers' 2, 8, 20, 28, 50, 82, 126 L41-8 9 Fe 26 56 Binding Energy 84 36 (MeV) binding energy / nucleon ( MeV) 8 7 6 5 4 3 2 1 1 1 3 2 Kr 1 235 Fission 235 92 92 U 1 6 3 Fu sion Li 0 n + U 92 36 Kr + 141 nuclear energy lighter 56 Ba + 3 0n He H 20 exothermic 1 1 `real' solar energy heavier real' 40 60 80 100 120 140 160 180 200 210 220 230 H + 1H 2 3 2 He 2004 M.Kubinec, H. Nitsche 2004 M.Kubinec, H.Nitsche mass L41-6 L42-1 Nuclear Decays Alpha Decay: Beta (-) Decay: ((neutron proton) proton) 238 92 U I 4 2 0 -1 0 +1 0 + 234 Th 90 e + 54 Xe + e + 10 Ne + 201 79 22 131 131 53 22 11 201 80 Beta (+) Decay: (proton neutron) neutron) (positron emission) (proton neutron) neutron) Na Electron Capture: Annihilation: 2004 M.Kubinec, H.Nitsche Hg + -1 e 0 -1 Au + 2 L42-2 e + +1 e 0 56 9 26 Fe Binding Energy 84 36 binding energy / nucleon (MeV) 8 7 6 5 4 3 2 1 1 1 3 Kr 1 235 Fission 235 92 92 U 1 6 3 Fu sion Li 0 n+ U 92 36 Kr + 141 nuclear energy lighter 56 Ba + 3 0n He 2 H 20 exothermic 1 1 `real' solar energy heavier real' 40 60 80 100 120 140 160 180 200 210 220 230 H + 1H 2 3 2 He 2004 M.Kubinec, H.Nitsche mass L42-3 2004 M.Kubinec, H.Nitsche 1 CHEM 1A L42:"RadiochemPrinciples" Nuclear Fission Chain Reaction More stable nuclides 2004 M.Kubinec, H.Nitsche L42-4 Mass - Energy Relation Annihilation: 0 -1 e + +1 e 0 2 E = 2 x h = mc2 h m = 2 x me = 2 x 5.48580 x 10-4 amu c2 = 931 MeV/amu 1 amu = 2 x 10-24 g 1 MeV = 1.6 x 2004 M.Kubinec, H.Nitsche E ~ 1.02 MeV J 10-13 E ~ 1011 J/mole chemical bond ~ 105 J/mole L42-5 ChemQuiz 41.3 What are the products of the following beta decays? 22Na 22Na -1e + + +1 e ??? ??? 1) 22Ne, 22Mg 2004 M.Kubinec, H.Nitsche 2) 21Na, 23Na 3) 21Ne, 23Mg L42-6 2004 M.Kubinec, H.Nitsche 2 CHEM 1A L42:"RadiochemPrinciples" ChemQuiz 41.4 How much energy (in eV) is released eV) when a positron and electron annihilate each other? Mass of the electron and positron is 5.486 x 10-4 amu 1) ~1 eV 2004 M.Kubinec, H.Nitsche 2) ~103 eV 3) ~106 eV L42-8 ChemQuiz 41.4 Solution How much energy (in eV) is released when a positron eV) and electron annihilate each other? E= mc2 For 1 e-, eE= (5.486 X 10-4 amu)(931.5 MeV/amu)= ~5X105 eV MeV/amu)= For an e- and an e+, E = 2 X 5X105 eV = ~106 eV e- 1) ~1 eV 2004 M.Kubinec, H.Nitsche 2) ~103 eV 3) ~106 eV L42-9 Summary 2004 M.Kubinec, H.Nitsche L42-10 2004 M.Kubinec, H.Nitsche 3 CHEM 1A L42:"RadiochemPrinciples" 90 38 100 Decay Rate Sr Half-life 0 90 -1 N (number of atoms) e + 39 Y 1 Curie (Ci) = 3.7 x 1010 disintegrations s-1 (Ci) exponential decay: Nt=Noe-t 29 y N half-life = t1/2 = 29 y: t1/2 = ln2/ ln2/ half10 half-lives ~ 99.9% decay half- 20 40 60 80 100 years 120 L42-11 2004 M.Kubinec, H.Nitsche ChemQuiz 42.1 A tritium luminescent watch manufactured in 1983 retains of its original intensity. intensity. What is the half life of tritium? 1) ~ 6 y 2004 M.Kubinec, H.Nitsche 2) ~ 12 y 3) ~ 24 y L42-12 ChemQuiz 42.2 Approximately what year will there be less than 0.1% of the tritium in the watch? 1) 2050 2004 M.Kubinec, H.Nitsche 2) 2100 3) 2500 L42-14 2004 M.Kubinec, H.Nitsche 4 CHEM 1A L42:"RadiochemPrinciples" Lecture Complete 2004 M.Kubinec, H.Nitsche L42-16 2004 M.Kubinec, H.Nitsche 5 ...
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This note was uploaded on 08/19/2009 for the course CHEM 1A taught by Professor Nitsche during the Spring '08 term at Berkeley.

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