Archives of Acoustics, 22, 1, pp. 93-102, 1997

Ultrasonic and thermodynamic effects of self-association of aliphatic alcohols in cyclohexane. III. Secondary and tertiary butanols

K. Bebek
Silesian University, Institute of Chemistry, Szkolna 9, 40-006 Katowice
Poland

E. Grzywna
Silesian University, Institute of Chemistry, Szkolna 9, 40-006 Katowice
Poland

S. Ernst
Silesian University, Institute of Chemistry, Szkolna 9, 40-006 Katowice
Poland

The ultrasound velocities in and densities of mixtures of
cyclohexane with 2-butanol
{x1sec-C4H9OH+(1-x1)C6H12} and with 2-methyl-2-propanol
{x1tert-C4H9OH+(1-x1)C6H12}
have been measured at 293.15K. The adiabatic compressibility coefficients,
βs=-1/V(∂V/∂p)s,
and compressibilities, κs=-(∂V/∂p)s,
as well as the excess molar volumes, VE,
and free intermolecular lengths, L, were determined in the whole concentration
range for both the systems studied. Using the measurement results in
connection with literature data, the isothermal compressibility
coefficients, βT=-1/V(∂V/∂p)T, and isochoric
molar heat capacities, Cv, for the pure components were calculated.
The above values were used to estimate the excess adiabatic
compressibilities, κsE, of the mixtures under test
accoring to the thermodynamically rigorous definitions recommended by Benson
et al. The dependences of those excess functions on the mixture
composition, reproduced by the Redlich-Kister equations, were
compared and discussed in terms of the free intermolecular length and
other factors affecting the self-association of alcohols (molecular
geometry of the hydro-carbon chain and position of the OH group).
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