Compressibilities apparatus, isothermal

Enantiomeric discrimination and its relation to film component reorganization upon compression can also be observed in dynamic surface tension hysteresis loops. Figure 26 shows the WjA isotherms generated upon five successive compression/expansion cycles (from II = 0 to lOdyncm-1) of racemic and enantiomeric films containing 17 mole percent palmitic acid. The hysteresis loops, obtained on the apparatus described in Section 2 (p. 63), show that the first compression/expansion cycle of the racemic system is repeated in each successive cycle. Upon expansion of the film from the maximum surface pressure back to Odyncm-1, the racemic film returns to its original state without detectable reorganization of the components. However, the... 

Despite the importance of mixtures containing steam as a component there is a shortage of thermodynamic data for such systems. At low densities the solubility of water in compressed gases has been used (J, 2 to obtain cross term second virial coefficients Bj2- At high densities the phase boundaries of several water + hydrocarbon systems have been determined (3,4). Data which would be of greatest value, pVT measurements, do not exist. Adsorption on the walls of a pVT apparatus causes such large errors that it has been a difficult task to determine the equation of state of pure steam, particularly at low densities. Flow calorimetric measurements, which are free from adsorption errors, offer an alternative route to thermodynamic information. Flow calorimetric measurements of the isothermal enthalpy-pressure coefficient pressure yield the quantity 4>c = B - TdB/dT where B is the second virial coefficient. From values of obtain values of B without recourse to pVT measurements. 

The experimental apparatus for measuring surface pressures has been described by Christodoulou and Rosano (4). The compression and expansion rates were between 0.009 and 0.03 cm/sec. Isotherms were determined when the system regained equilibrium after short periods of compression. 

The experimental procedures for the determination of and are different. One can measure in a thermomechanical analysis (TMA) apparatus and then calculate from it. Or, one can determine directly by using an apparatus which produces fitll P-V-T data, that is specific volume v as a function of temperature T, v(T), plus (T) plus also isothermal compressibility. /T), where... 

Zander [3.66] carried out a very detailed investigation of pvT behavior of liquid and gaseous Freon-22 on two experimental apparatuses. Compressibility of gaseous Freon-22 was determined by the Burnett method and produced 107 experimental values z(p, T) on seven isotherms in the interval T = 303-473 K at pressure of 0.3-34 MPa. According to Zander s assertions, the maximum error in the results does not exceed 0.25%. The second apparatus was a con-... 

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