Chemistry



Name:________________________Hour:____Date:___________AP Chemistry: 6HW1A. What is the wavelength (in nanometers) of a photon having a frequency of 8.7 x 1015 s–1? 1B. Find the frequency of a radio wave having a wavelength of 0.31 km. 2A. How many 860 nm photons are contained in a 2.7 ?J pulse of monochromatic radiation?2B. Over a 15.8 s time span, a radiation sensor measures 41 mW of power due to 5.5 x 1013 photons hitting its surface. What is the wavelength of these photons? (1 W = 1 J/s)3A. A single photon of wavelength 1270 angstroms carries enough energy to break one nitrogen-nitrogen triple bond. What is the bond enthalpy of the N2 triple bond?ANSWERS:1A. 34 nm2A. 1.2 x 1013 photons3A. 1.57 x 10–18 J1B. 9.7 x 105 s–1 (or 9.7 x 105 Hz)2B. 1.7 x 10–11 m3B. Carbon-oxygen double bonds have a bond enthalpy of 782 kJ/mol. How many photons of wavelength 7.8 ?m are required to break a single C=O bond?4A. In the photoelectric effect, the energy needed to knock an electron out from a metal’s surface is called the work function. Zinc has a work function of 4.3 eV (electron-volts). A photon having what maximum wavelength is required to eject an electron from the surface of zinc? (1 eV = 1.6 x 10–19 J)4B. Cesium has a work function of 2.1 eV. If a photon of wavelength 8.6 x 10–8 m is absorbed by an electron in a cesium atom, with what kinetic energy will the electron be ejected?5A. How much energy must be absorbed for an electron in a hydrogen atom to jump from the third to the sixth energy level?5B. How much energy (in kJ/mol) must be absorbed to eject n = 1 electrons from a hydrogen atom? ANSWERS:3B. 51 photons 4A. 2.9 x 10–7 m4B. 2.0 x 10–18 J 5A. 1.82 x 10–19 J5B. 1,300 kJ/mol6A. A photon of what frequency is emitted from a hydrogen atom when an electron falls from n = 4 to n = 1?6B. A 1.28 micron photon is emitted when an electron in a hydrogen atom falls from n = 5 to n = ?7A. What is the de Broglie wavelength for a fluorine molecule moving at 320 m/s?7B. A muon is a subatomic particle having 11.3% of the mass of a proton. Calculate the de Broglie wavelength (in angstroms) for a muon traveling at 6.18 x 104 km/h. ANSWERS:6A. 3.1 x 1015 Hz (or 3.1 x 1015 s–1) 6B. n = 3 7A. 3.3 x 10–11 m7B. 2.06 angstroms8A. What is the uncertainty in the position of a neutron moving at a speed of (6.00 +/– 0.01) x 104 m/s?8B. What is the uncertainty in the position of an electron moving at a speed of (8.50 +/– 0.01) x 107 m/s? It takes about 1836 electrons to equal the mass of a single proton.9. Give the values of n, l, and m for each orbital in the 4d subshell.Write condensed electron configurations for each of the following. 10A.Ge10B. Ag+BaFe2+AgCu2+ANSWERS:8A. 3 x 10–10 m 8B. 6 x 10–10 m 11A. Suppose that a microwave oven heats food by emitting photons of wavelength 12.6 cm. About how many photons must be absorbed by 250 mL of coffee to heat it from 20.oC to 78oC?11B. A 950 g sample of 22oC water is placed outside on a winter night. To freeze completely solid, the water must emit the energy equivalent of HOW MANY infrared photons of wavelength 8.75 x 10–4 m?ANSWERS:11A. 3.8 x 1028 photons 11B. 1.8 x 1027 photons ................
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