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Session #3: Homework Problems Problem #1 From a standard radio dial, determine the maximum and minimum wavelengths ( λmax and λmin ) for broadcasts on the (a) AM band (b) FM band Problem #2 For light with a wavelength ( λ ) of 408 nm determine: (a) (b) (c) (d) (e) the the the the the frequency wave number wavelength in Å total energy (in Joules) associated with 1 mole of photons “color” Problem #3 For “yellow radiation” (frequency, ν , = 5.09 x 1014 s–1) emitted by activated sodium, determine: (a) the wavelength ( λ ) in [m] (b) the wave number ( ν ) in [cm–1] (c) the total energy (in kJ) associated with 1 mole of photons Problem #4 Potassium metal can be used as the active surface in a photodiode because electrons are relatively easily removed from a potassium surface. The energy needed is 2.15 x 105 J per mole of electrons removed (1 mole =6.02 x 1023 electrons). What is the longest wavelength light (in nm) with quanta of sufficient energy to eject electrons from a potassium photodiode surface? Problem #5 For red light of wavelength ( λ ) 6.7102 x 10–5 cm, emitted by excited lithium atoms, calculate: (a) the frequency ( ν ) in s–1; (b) the wave number ( ν ) in cm–1; (c) the wavelength ( λ ) in nm; (d) the total energy (in Joules) associated with 1 mole photons of the indicated wavelength. Problem #6 Calculate the “Bohr radius” for He+. Problem #7 (a) Determine the atomic weight of He++ from the values of its constituents. (b) Compare the value obtained in (a) with the value listed in your Periodic Table and explain any discrepancy if such is observed. (There is only one natural isotope.) 4 2He MIT OpenCourseWare http://ocw.mit.edu 3.091SC Introduction to Solid State Chemistry Fall 2009 For information about citing these materials or our Terms of Use, visit: http://ocw.mit.edu/terms.