CHAPTER 25 Nuclear Chemistry

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CHAPTER 25 Nuclear Chemistry
I

• III. Fission Fusion
• (p. 717 - 719)

II
III
IV
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A. F ission

• Nuclear Reactions produce exponentially more
  energy than chemical reactions. (nuclear bomb vs.
  dynamite chemical bombs)
• Fission is splitting
• a nucleus into two
• or more smaller nuclei
• 1 g of 235U 3 tons of coal

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A. F ission

• chain reaction - self-propagating reaction
• critical mass - mass required to sustain a
  chain reaction
• Super-critical is
• when chain rxn
• goes too fast
• MELTDOWN

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B. Fusion

• combining of two nuclei to form one nucleus of
  larger mass
• thermonuclear reaction requires temp of
  40,000,000 K to sustain
• 1 g of fusion fuel 20 tons of coal
• occurs naturally in stars

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C. Fission vs. Fusion
FISSION
FUSION

• 235U is limited
• danger of meltdown
• toxic waste
• thermal pollution

• Heavy hydrogen fuel is abundant
• no danger of meltdown
• no toxic waste
• not yet sustainable

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CHAPTER 25 Nuclear Chemistry
I

• IV. Applications

II
III
IV
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A. Nuclear Power

• Fission Reactors

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A. Nuclear Power

• Fission Reactors

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A. Nuclear Power

• Fusion Reactors (not yet sustainable)

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A. Nuclear Power

• Fusion Reactors (not yet sustainable)

National Spherical Torus Experiment
Tokamak Fusion Test Reactor Princeton University
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B. Synthetic Elements

• Transuranium Elements
• elements with atomic s above 92
• synthetically produced in nuclear reactors and
  accelerators
• most decay very rapidly

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C. Radioactive Dating

• half-life measurements of radioactive elements
  are used to determine the age of an object
• decay rate and amount of radioactive material
  remaining indicate the age
• EX 14C can date ages of up to 40,000
  years 238U and 40K - over 300,000 years old

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PET Scan

• Positron Emission Topography
• Inject or swallow a sugar with a radioactive tag
  that emits positron, which are measured by a
  scanner

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D. Nuclear Medicine

• Radioisotope Tracers (bonded to sugars, proteins,
  or medicines)
• absorbed by specific organs and used to diagnose
  diseases
• Radiation Treatment
• larger doses are used to kill cancerous cells
  in targeted organs
• internal or external radiation source

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E. Nuclear Weapons

• Atomic Bomb
• chemical explosion is used to form a critical
  mass of 235U or 239Pu
• fission develops into an uncontrolled chain
  reaction
• Hydrogen Bomb
• chemical explosion ? fission ? fusion
• fusion increases the fission rate
• more powerful than the atomic bomb

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F. Others

• Food Irradiation
• ? radiation is used to kill bacteria
• Radioactive Tracers
• explore chemical pathways
• trace water flow
• study plant growth, photosynthesis
• Consumer Products
• ionizing smoke detectors - 241Am