Interpretation:
The vibrational partition function for
Concept introduction:
A molecule is made up of atoms that are bonded together by covalent bonds. These bonds undergo a to and fro movement to vibrate. This vibration of the molecule contributes to the overall partition function of the system. The vibrational partition function of the polyatomic molecule is represented as,
Where,
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Student Solutions Manual for Ball's Physical Chemistry, 2nd
- Part A Determine the total molecular partition function for gaseous H2O at 1000. K confined to a volume of 2.20 cm³. The rotational constants for water are BA = 27.8 cm, BB = 14.5 cm¯', and Bc = 9.95 cm. The vibrational frequencies are 1615, 3694, and 3802 cm-. The ground electronic state is nondegenerate. (Note: the Avogadro's constant NA = 6.022 × 1023 mol-1). Express your answer to three significant figures. Ην ΑΣφ qtotal = Submit Request Answerarrow_forward5. The vibrational modes of a particular molecule are listed below. Calculate the vibrational contribution to the molar entropy at 300 K. Mode Degeneracy wavenumber / cm-1 v1 206 v2 305 v3 1083 v4 1367 USEFUL CONSTANTS R = 8.314 J/mol/K = 0.08205 Latm/mol/K kB =1.38 x10-23 J/K h = 6.626×10-34 J s c = 3x108 m/s 1 cm-1 = 1.98x10-23 J STP = 298 K, 1bar (105 N/m²) 12 3arrow_forwardConsider a system of distinguishable particles having only two non-degenerate levels separated by an energy that is equal to the value of kT at 10 K. Calculate (a) the ratio of populations in two states at (1) 1.0 K, (2) 10 K, (3) 100 K, (b) the molecular partition function at 10 K, (c) the molar energy at 10 K, (d) the molar heat capacity at 10 K, € the molar entropy at 10 K.arrow_forward
- A linear molecule may rotate about two axes. If the molecule consists of N atoms, then there are 3N- 5 vibrational modes. Use the equipartition theorem to estimate the total contribution to the molar internal energy from translation, vibration, and rotation for (a) carbon dioxide, CO2, and (b) dibromoethyne, C2Br2, at 2000 K. In contrast, a nonlinear molecule may rotate about three axes and has 3N- 6 vibrational modes. Estimate the total contribution to the molar in ternal energy from translation, vibration, and rotation for (c) nitrogen dioxide, NO2, and (d) tetrabromoethene, C2Br4,at 2000 K. In each case, first assume that all vibrations are active; then assume that none is.arrow_forwardAt what temperature is the standard molar entropy of helium equal to that of xenon at 298 K?arrow_forwardCalculate, by explicit summation, the vibrational partition function of I2 molecules at (a) 100 K, (b) 298 K given that its vibrational energy levels lie at the following wavenumbers above the zero-point energy level: 0, 215.30, 425.39, 636.27, 845.93 cm−1. What proportion of I2 molecules are in the ground and first two excited levels at the two temperatures?arrow_forward
- A CO2 molecule has four vibrational modes with wavenumbers 1388 cm-1, 2349 cm-1, and 667 cm-1, (the last being a doubly degenerate bending motion). Calculate the total vibrational partition function at (a) 500 K, (b) 1000 K.arrow_forwardA certain atom has a fourfold degenerate ground level, a non-degenerate electronically excited level at 2500 cm−1, and a twofold degenerate level at 3500 cm−1. Calculate the partition function of these electronic states at 1900 K. What is the relative population of each level at 1900 K?arrow_forwardA certain atom has a triply degenerate ground level, a non-degenerate electronically excited level at 850 cm–1, and a fivefold degenerate level at 1100 cm−1. Calculate the partition function of these electronic states at 2000 K. What is the relative population of each level at 2000 K?arrow_forward
- Estimate the vibrational contribution to the molar entropy of the most common isotopomer of bromine, 79Br2, at 1000 K. The vibrational wavenumber for 79Br2 is 325 cm-1. You may assume that at this temperature, the equipartition theorem and the high temperature approximation for the vibrational partition function are both valid.arrow_forwardThe methyl chloride molecule, CH3Cl, has three non-degenerate vibrations with harmonic wavenumbers 3088, 1396 and 751 cm–1 respectively and three doubly-degenerate vibrations with harmonic wavenumbers 3183, 1496 and 1036 cm–1 respectively. Calculate the vibrational partition function for the methyl chloride molecule at 1200 K.arrow_forwardN2O and CO2 have similar rotational constants (12.6 and 11.7 GHz, respect ively) but strikingly different rotational partition functions. Why?arrow_forward
- Physical ChemistryChemistryISBN:9781133958437Author:Ball, David W. (david Warren), BAER, TomasPublisher:Wadsworth Cengage Learning,