Entropy vaporization table

Tables 2,3, and 4 outline many of the physical and thermodynamic properties ofpara- and normal hydrogen in the sohd, hquid, and gaseous states, respectively. Extensive tabulations of all the thermodynamic and transport properties hsted in these tables from the triple point to 3000 K and at 0.01—100 MPa (1—14,500 psi) are available (5,39). Additional properties, including accommodation coefficients, thermal diffusivity, virial coefficients, index of refraction, Joule-Thorns on coefficients, Prandti numbers, vapor pressures, infrared absorption, and heat transfer and thermal transpiration parameters are also available (5,40). Thermodynamic properties for hydrogen at 300—20,000 K and 10 Pa to 10.4 MPa (lO " -103 atm) (41) and transport properties at 1,000—30,000 K and 0.1—3.0 MPa (1—30 atm) (42) have been compiled. Enthalpy—entropy tabulations for hydrogen over the range 3—100,000 K and 0.001—101.3 MPa (0.01—1000 atm) have been made (43). Many physical properties for the other isotopes of hydrogen (deuterium and tritium) have also been compiled (44).

Values for many properties can be determined using reference substances, including density, surface tension, viscosity, partition coefficient, solubihty, diffusion coefficient, vapor pressure, latent heat, critical properties, entropies of vaporization, heats of solution, coUigative properties, and activity coefficients. Table 1 Hsts the equations needed for determining these properties. 

To use a thermodynamic graph, locate the fluid s initial state on the graph. (For a saturated fluid, this point lies either on the saturated liquid or on the saturated vapor curve, at a pressure py) Read the enthalpy hy volume v, and entropy from the graph. If thermodynamic tables are used, interpolate these values from the tables. Calculate the specific internal energy in the initial state , with Eq. (6.3.23). 

When thermodynamic tables are used, read the enthalpy hf, volume Vj, and entropy Sf of the saturated liquid at ambient pressure, po, interpolating if necessary. In the same way, read these values (hg, Vg, Sg) for the saturated vapor state at ambient pressure. Then use the following equation to calculate the specific internal energy... 

In adiabatic compression or expansion, no release or gain of heat by the gas occurs, and no change occurs in entropy. This condition is also known as isentropic and is typical of most compression steps. Actual conditions often cause a realistic deviation, but usually these are not sufficiently great to make the calculations in error. Table 12-4 gives representative average k values for a few common gases and vapors. 

Self-Test 7.6A Calculate the standard entropy of vaporization of argon at its boiling point (see Table 6.3). 

Table 7.1 lists the standard entropies of vaporization of a number of liquids. These and other data show a striking pattern many values are close to 85 J-K 1-mol h This observation is called Trouton s rule. The explanation of Trouton s rule is that approximately the same increase in positional disorder occurs when any liquid is converted into vapor, and so we can expect the... 

TABLE 7.1 Standard Entropy of Vaporization at the Normal Boiling Point ... 

C14-0051. Table lists molar enthalpies of vaporization of several substances. Calculate the molar entropy of vaporization at its normal boiling point for each of the following (a) molecular oxygen (b) ethane (c) benzene and (d) mercury. 

Explain the entropy of vaporization data given in Table 12.1 for A1(C2H5)2C1 and A1(C2HS)C12 in terms of the species present in both the liquid and vapor phases. 

At its boiling point, what is the entropy change of benzene from a liquid to vapor per gram Use Table 6.1. 

The next set of examples show an entropy of adsorption roughly equal to the entropy change on losing the degree of translational freedom normal to the surface, i.e., in the adsorbed state the molecules are equivalent to a two-dimensional gas or vapor. The data for a variety of different adsorbates and adsorbents is given in Table V. The isotherms obtained by Armbruster (20) for the adsorption of CO and N2 on silver were not S-shaped, and they could be fitted to equations of the Langmuir type. The amount of adsorbate required to saturate the surface was given for each substance at both temperatures. Armbruster calculated the heats of adsorption by the method of Brunauer, Emmett and Teller (22) and there is some doubt about the validity of such heats. 

This A p-S Tt,) value is typical for many other organic compounds that boil at very different temperatures (Table 4.2). In fact, long ago, Trouton (1884) recognized that the entropy of vaporization at the boiling point for many apolar and monopolar substances is more or less constant between 85 and 90 J moT1 K 1. Note that the constancy of A S Ti,) implies that there must be a close relationship between AmpH,(Tb) and Tb. 

Table 4.2 Variations in Normal Boiling Points, Liquid Vapor Pressure at 25°C, Observed Enthalpies and Entropies, and Predicted Entropies of Vaporization at the Boiling Point of Substituted Benzenes and Some Other Compounds a... 

For bipolar organic liquids, especially for hydrogen-bonding liquids such as alcohols and amines, the tendency to orient in the liquid phase, due to these highly directional intermolecular attractions, is greatly increased by this intermolecular interaction. We can see the effect of this in the significantly larger entropies of vaporization of bipolar chemicals, like aniline, phenol, benzyl alcohol, or ethanol (Table 4.2). 

To calculate the standard entropy of vaporization of acetone at its boiling point of 329.4 K (corresponding to 56.2°C), we note from Table 6.2 that its standard enthalpy of vaporization at its boiling point is 29.1 kjmol-1. - Therefore, from Eq. 5, its standard entropy of vaporization at its boiling point is... 

The standard entropies of vaporization of a number of liquids are given in Table 7.1. When these and other data are considered, a striking feature is that many are reasonably close to 85 J-K -mol-1. This obser-... 

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