15CHM11509 HIK - CHM 115 Dr. Chitta Das Lecture 15 Lecture...

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CHM 115 Dr. Chitta Das Lecture 15 Lecture 16: Sections 9.8 (part), pp. 408-412 Section 13.2-13.4, pp. 591-606 Section 5.8, pp. 205-212 Section14.1-14.2, pp. 658-668 Next lab: Concentration and Spectroscopy
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Next Lab: Concentration and Spectroscopy This laboratory will give you an opportunity to work with an example of a very common analytical technique used in all types of labs, not just chemistry labs.
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Not everything that is clear and colorless is the same substance: How can we tell them apart? DEMO: pure water, tonic water; black (UV) light source
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Energy (“light”) + Matter (molecules) region of spectrum wavelength range molecular effects …and this means… gamma pm – nm ionizing damage DNA UV-C 200-280 nm break bonds Highly damaging; totally absorbed by O 2 and O 3 in upper atmosphere UV-B 280-320 nm break bonds Sunburn and skin cancer. Absorbed by O 3 in stratosphere. UV-A 320-400 break bonds/ electron transitions A lot reaches surface of earth through atmosphere; can result in eye damage; tanning Visible 400-700 nm electron transitions Results in color IR (near) 700-5000 nm bond vibrations spectroscopy to look at structures of molecules Microwave 1 mm – 1 m bond rotations Microwave ovens
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Stratosphere: UV and ozone O 3 + h ν (280-320 nm) O 2 + O O 2 + O O 3 Ozone in upper atmosphere absorbs in the UV-B range. It is then spontaneously regenerated from products. Ozone protects us from damaging radiation.
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This note was uploaded on 02/06/2012 for the course CHM 115 taught by Professor Towns during the Spring '08 term at Purdue University.

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15CHM11509 HIK - CHM 115 Dr. Chitta Das Lecture 15 Lecture...

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