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Drill:

Drill:. Calculate the solubility of MgF 2 in 0.10 M KF. K sp MgF 2 = 6.4 x 10 -9. Drill: A statue is electroplated at the cathode using a silver anode in aqueous AgNO 3 . Calculate the current required to plate 10.8 g of silver in 5.0 minutes.

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Drill:

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  1. Drill: • Calculate the solubility of MgF2 in 0.10 M KF. • KspMgF2 = 6.4 x 10-9

  2. Drill: A statue is electroplated at the cathode using a silver anode in aqueous AgNO3. Calculate the current required to plate 10.8 g of silver in 5.0 minutes.

  3. Drill: Calculate the volume of Cl2 formed at 27oC under 75 kPa when xs molten NaCl is electrolyzed with 96.5 mA for 5.0 mins.

  4. Nuclear Chemistry

  5. Nuclear Chemistry • The study of reactions that take place in the nuclei of atoms

  6. Chemical Reactions • In normal chemical reactions, only the electrons are involved

  7. Radioactive Nuclei • Nuclei that spontaneously decompose

  8. Isotopes • Elements with the same atomic number, but different mass number

  9. Isotopes • Elements with = numbers of protons, but  numbers of neutrons

  10. Isotopes • All elements have at least one radioactive isotope

  11. Nuclear Radiation • The emission of particles & rays from spontaneously decomposing nuclei

  12. Modes of Decay • Alpha emission • Beta emission • Gamma emission • Positron emission • K-electron capture

  13. Alpha Particle (a) • Helium nucleus • 2 protons & 2 neutrons • mass = 4 amu • charge = +2 • Penetration power: small

  14. Beta Particle (b) • High speed electron • 1 electron • mass = 1/1836 amu • charge = -1 • Penetration power: medium

  15. Gamma Ray (g) • High energy photon • Electromagnetic wave • mass = 0 • charge = 0 • Penetration power: great

  16. Positron (p) • Positive electron • 1 positive electron • mass = 1/1836 amu • charge = +1 • Penetration power: medium

  17. K-capture • The capture of an inner level e- by the nucleus • 1 electron • mass = 1/1836 amu • charge = -1

  18. Nuclear Symbol • Alpha: 24Heor24a • Beta: -10eor –10b • Gamma: 0 0 • Positron: +10e • K-electron: -10e

  19. Fission • The splitting of a nucleus into smaller nuclei involving the release of energy

  20. Fusion • The combining of smaller nuclei into a larger nucleus involving the release of energy

  21. Drill: • Name & describe 3 types of radiation

  22. Fission • The splitting of a nucleus into smaller nuclei involving the release of energy

  23. Fusion • The combining of smaller nuclei into a larger one involving the release of energy

  24. Transmutation Rxns • Nuclear reactions in which one element is changed into another

  25. Transmutation Rxns • Reactions in which the nucleus of an atom is changed

  26. Transmutation Rxns • Both fission & fusion are examples of transmutation rxns

  27. Transmutation Rxns • Can occur through emission of or bombardment by particles

  28. Nuclear Symbol • Alpha: 24Heor24a • Beta: -10eor –10b • Gamma: 0 0

  29. Nuclear Symbols Neutron 01n Proton 11p Electron -10e

  30. Transmutation Rxns • b emission of Pm-142 • a bombardment of Th-231

  31. Transmutation Rxns • a emission ofU-238 followed by two separate b emissions:

  32. Transmutation Rxns • a bombardment ofTh-235 followed by two separate b emission:

  33. Predict Products • a emission of O-18 followed by a • b emission:

  34. Predict Products • b absorption by V-45 followed by neutron emission then a emission

  35. Predict Products • neutron bombardment of Ta-182 followed by b emission then a emission

  36. Drill: Predict Prod • Neutron absorption by U-238 followed by two separate b emission:

  37. Nuclear Power

  38. Nuclear Fission • U-235 is the only fissable isotope of uranium • 0.71 % of uranium is U-235 • 99.28 % of uranium is U-238

  39. Nuclear Fission • Chain reaction can occur only when it reaches critical mass • The percentage of U-235 in uranium is too low to form a chain reaction

  40. Nuclear Fission • To run a power plant, the U-235 needs to be enriched to ~ 2% • To make a bomb, the U-235 needs to be enriched to > 70%

  41. Nuclear Fission • To create a chain reaction, the U-235 % must be increased (enriched) greatly • Ultra-centrifugation

  42. Nuclear Fission Bomb

  43. Decay Rate • The rate at which radioactive nuclei break down

  44. Half-Life • The time it takes for 50 % of the radioactive nuclei to decompose

  45. Decay Rate • Rate = kDX/Dt • ln(Xi/Xf) = kt1/2 • k = 0.693/t1/2 • t1/2 = half-life

  46. 1st Order Age Dating Formula • ln(Xi/Xf)t1/2 • 0.693 t =

  47. Calculate the age of a skeleton found with 0.125 % C-14 when atmospheric C-14 = 1.00 %. • t1/2 C-14 = 5730 yr

  48. Calculate the age of a tooth found with 0.00132 % C-14 when atmospheric C-14 = 1.00 %. • t1/2 C-14 = 5730

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