Heat Capacity, Gas Imperfection, Infrared Spectra, and Internal Rotation Barriers of Ethyl Alcohol

The vapor heat capacities of ethyl alcohol have been measured, as a function of pressure, at 368, 422, and 476°K. From the variation of the heat capacity with pressure, together with vapor densities calculated by the Clapeyron equation, an equation of state for ethyl alcohol has been obtained. This equation has been used to extrapolate the measured heat capacities to the ideal gas state and likewise to correct the observed entropy.The infrared spectra of vapor C2H5OH, C2H5OD, and liquid C2H5OD are presented and a vibrational assignment is obtained which is sufficiently reliable for the statistical calculation of the thermodynamic properties.Comparison of the observed and statistically calculated heat capacities and entropies shows that, with a barrier to internal rotation of the CH3 group of 3000 calories, the rotation of the OH group is hindered by a barrier between 0 and 1200 calories. Most satisfactory agreement is obtained for CH3 and OH barriers of 3300 and 800 calories, respectively. Furthermore, co...

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