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UV AND
MICROWAVES…read more

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UV to initiate reactions
· NAME: Ultraviolet (UV) radiation
· TYPE: Form of electromagnetic radiation
· WAVELENGTH: Wavelength between that of
visible light and x-rays 400nm to 10nm
· USE: Enough energy to split molecules
produce free radicals
· MECHANISM: Homolytic fission each atom
takes one electron from covalent bond
· EXAMPLE: E.g. splitting of chlorine molecule into
2 chlorine free radicals…read more

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Chlorine and methane reaction using
UV radiation
· Initiation step free radicals created
· Cl2 (+ UV) Cl. + Cl.
· Propagation steps free radicals re-created
· CH4 + Cl. CH3. + HCl
· CH3. + Cl2 CH3Cl + Cl.
· Termination steps two free radicals combine
· Cl. + Cl. Cl2
· Cl. + CH3. CH3Cl
· CH3. + CH3. C2H6…read more

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Creation of chlorine free radicals from
CFC's using UV radiation
· WHERE: In outer edge of atmosphere
· TYPE OF UV: UV from sunlight
· INITIATION STEP: CF3Cl (+ UV) CF3 + Cl.
· DANGER: Ozone broken down by Cl.
needed to protect Earth's surface from UV
radiation
· PROPAGATION STEPS: Cl. + O3 O2 + ClO.
ClO. + O3 Cl. + 2O2…read more

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Microwaves
· TYPE: Form of electromagnetic radiation
· WAVELENGTH: Wavelength between that of infrared and radio
waves 1mm to 1m
· USE: For heating/communications
· WAVELENGTH OF MICOWAVES FOR HEATING: Microwave oven
uses wavelength of 12.24cm
· POLAR BONDS: Polar bond when there are 2 atoms of different
electronegativity's in a covalent bond, causing electrons to be
pulled towards the more electronegative atom
· WATER POLARITY: Oxygen of water more electronegative than
hydrogen so electrons pulled towards oxygen atom polar bonds
· HOW MICROWAVE OVENS WORK: Microwaves pass through food,
causing electromagnetic field; polar molecules try to line up with
electromagnetic field by rotating; polar molecules collide, releasing
heat energy…read more

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