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Unformatted text preview: Practice Problem 11 – Answer Which is higher in energy? (a) Infrared radiation of 1715 cm–1 or of 2800 cm–1? (b) Radiofrequency radiation of 300 MHz or 60 MHz? (c) Infrared radiation with = 1.0 x 10–6 m or an X ray with = 3.0 x 10–9 m? Remember that energy is directly proportional to frequency (), and inversely proportional to wavelength (). A larger frequency therefore corresponds to HIGHER energy, while a larger wavelength corresponds to a SMALLER energy. (d) Radiation with = 4.0 x 109 Hz or radiation with = 9.0 x 10–6 m? Use the expression c = to convert the given to its corresponding frequency: Practice Problem 12 – Answer Because IR absorptions can be expressed either in micrometers or in wavenumbers, it is useful to be able to interconvert between units. Do the following conversions: (a) 3.10 m to cm–1 Recall that , 1 m = 1 x 10–6 m, and 1 cm = 1 x 10–2 m. Each wavelength must therefore be converted from mm to cm before taking its inverse to determine the frequency expressed in wavenumbers (cm –1). (b) 5.85 m to cm–1 Follow the same procedure used in part (a): (c) 2250 cm–1 to m Taking the inverse of the frequency expressed in cm–1 will give the wavelength in cm. Use the metric conversion factors given above to convert from cm to m: (d) 1720 cm–1 to m Follow the same procedure used in part (c): ...
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This note was uploaded on 10/25/2010 for the course CH 310n taught by Professor Iverson during the Summer '08 term at University of Texas.
 Summer '08
 Iverson

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