Activation energy

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  • Created by: boggleme
  • Created on: 03-12-14 16:54
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  • Activation energy
    • average thermal energy per particle = kT
      • to change units to eV, divide by the charge on the electron (1.6*10^-19)
    • Ratio activation energy/kT is called the magic ratio - when this ratio is between 15 and 30, reactions occur and bonds break
      • any higher than this and nothing happens
      • any lower than this and the bonds have already broken
    • Processes...
      • a change of state
      • thermionic emision (electrons being released from the surface of a conductor when it is heated)
      • conduction in a semiconfuctor
      • viscous flow (heating a liquid so parkinetic enegy is increased
    • each time particles collide, there is a chance the one of them with gain extra energy
      • f is the fraction of particles with extra energy E and if E is big compared to kT, then f will be small
        • fraction of particles with extra energy 2E = f*f and so the fraction of particles with extra energy xE is f^x.
    • there is a huge number of particles colliding billions of times a second so the small fraction of particles gaining energy still adds up to a large number of particles


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