Number of Degrees of Freedom How many rotational and vibrational degrees of freedom do the following molecules have? O 2 4 3
Experimental Methods in Molecular Spectroscopy Absorption spectra can be recorded with a spectrophotometer. Measure transmittanceT= IS/IRor absorbanceA= ln[IR/IS] vs.λ.Relate to molecular properties: –lnIS/IR⎡⎣⎤⎦=–lnT=A=a, where is the cell length.Parameter ais the absorption, or extinction, coefficient(units: length–1) NOTE: In Intro Chem Lab, Adefined as log10[IR/IS]. Values will differ by factor of ln(10) = 2.303. Log10is used in solution manual.
Problem The percent transmission at 250 nm through a certain aqueous solution is 20%. The cell length is 1.0 cm, and the solution concentration is 5✕10–4mol L–1. Calculate the molar absorption coefficient.