Chemistry 440 Problem Set 1 Fall 2011 Due: September 8, 2011 1. In early 1999 it was thought that the first planet outside the solar system had been photographed; by midsummer of that year, the ‘planet’ had been reclassified as a cool star with surface temperature 2500˚C. What is the wavelength of its maximum emission? 2. Calculate the size of the quantum involved in the excitation of (a) an electronic motion of frequency 1.0 x 10 15 Hz, (b) a molecular vibration of period 20 fs, (c) a pendulum of period 0.50 s. Express the results in joules and in kilojoules per mole. 3. The workfunction for metallic caesium is 2.14 eV. Calculate the kinetic energy and the speed of the electrons ejected by light of wavelength (a) 750 nm, (b) 250 nm. 4. The energy required for the ionization of a certain atom is 3.44 aJ (1 aJ – 10-18 J; a denotes ‘atto’). The absorption of a photon of unknown wavelength ionizes the atom and ejects an electron with velocity 1.03 x 10 6 m s-1 .
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