Download Physical Chemistry Midterm: Atomic & Molecular Physics, Spectroscopy, Thermodynamics Quest and more Exams Physical Chemistry in PDF only on Docsity! 1 Chemistry 331 Physical Chemistry Practice Midterm Section _______ Name ________________________________ Given: g = 9.81 m/s2 R = 8.314 J mol-1 K-1 = 0.08206 L atm mol-1 K-1 1 a.m.u. = 1.67 x 10-27 kg Electron charge = 1.62 x 10-19 C 1 Debye = 3.33 x 10-30 Cm 1 atm = 1.0133 x 105 Nm-2 = 760 Torr P = P0exp{-Mgh/RT} ω = kµ , B = h 8π2cµR2 , µ = m1m2 m1 + m2 , λ = hp , T2 T1 = V1V2 R/CV 1. A researcher has a laser that has a 250 nm wavelength. Which of the metals in the table below can be used to generate electrons? What is the highest energy electron that can be generated? Metal Electron Work Function Al 4.28 eV Au 5.10 eV Cu 4.65 eV In 4.12 eV Mo 4.60 eV Ni 5.15 eV Pt 5.65 eV Ti 4.33 eV W 4.55 eV Zn 4.33 eV Energy of a 250 nm photon (4 points) = __________________________________. Appropriate metals that satisy criterion (4 points) = _________________________. Highest energy electron that can be generated (2 points) = _____________________. 2 2. A white dwarf collapses and then explodes into a supernova. The peak of the blackbody emission is observed to shift from 400 nm to 300 nm. A. and B. What is the change in temperature of the surface of star as it becomes a supernova? C. What is the relative increase in radiative emitted power? A. T at 300 nm (3 points) = _____________________________________. B. T at 400 nm (3 points) = _____________________________________. C. Relative increase in radiative power (4 points) = ________________________. 3. A. The molecule Integrafor has a fluorescence quantum yield of 0.75 and an observed decay lifetime of 50 ns. Please determine the fluorescence rate constant (kf) and the internal conversion (or non-radiative decay) rate constant (kIC). kf = ________________________ (5 points) kIC = ___________________ (5 points) B. A scientist synthesizes the molecule bromo-Integrafor with a fluorescence quantum yield of 0.1. The bromine causes a spin transition (singlet triplet) because of the heavy atom effect. Assuming that kf and kIC are unchanged and that the origin of this effect is a third process is a rate constant for intersystem crossing kISC. Calculate the expected observed fluorescence lifetime for bromo-Integrafor. Please calculate the phosphorescence quantum yield (i.e. the quantum yield for emission from the triplet state ΦISC). τobs = _______________________________________ (5 points). ΦISC = _______________________________________ (3 points). 4. A. Calculate the energy of the transition series 6p 2s, 5p 2s, 4p 2s in the hydrogen atom. B. Calculate the wavelength of light emitted for the 6p 2s, 5p
