Chemical Forums
Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: captainkittles on April 20, 2009, 01:54:23 AM
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I cannot figure the following problems out and would LOVE some help:
1) The number of collisions, z, that a molecule in the gas phase makes per unit time, when only one species is present, is given by
z = pi x d^2 (8kT/pi)^(1/2) p/kT
where d is the collision diameter, m is the molecular mass, T the temperature, and p the pressure. For benzene at 1 Torr and 293K, and assuming d = 5 angstroms, calculate z and hence the pressure broadening change in v, in hertz, of observed transitions
2) Calculate in hertz the broadening change in v of transitions in HCN at 25 degrees celsius due to the DOppler effect in regions of the spectrum typical of rotational transitions (10/cm), vibrational transitions (1500/cm) and electronic transitions (60,000/cm).
3) As a function of frequency, the spectral radiation density is given by
density(v) = [(8 x pi x h x v^3) / c^3] x [1 / (exp(hv/kT) - 1]
Calculate typical values in the microwave (w = 50 GHz) and near-ultraviolet (wavenumber = 30,000/cm)
ANY HELP WOULD BE VERY APPRECIATED!!!!!!