Chlorine enthalpy-pressure

Chlorine, a member of the halogen family, is a greenish yellow gas having a pungent odor at ambient temperatures and pressures and a density 2.5 times that of air. In Hquid form it is clear amber SoHd chlorine forms pale yellow crystals. The principal properties of chlorine are presented in Table 15 additional details are available (77—79). The temperature dependence of the density of gaseous (Fig. 31) and Hquid (Fig. 32) chlorine, and vapor pressure (Fig. 33) are illustrated. Enthalpy pressure data can be found in ref. 78. The vapor pressure P can be calculated in the temperature (T) range of 172—417 K from the Martin-Shin-Kapoor equation (80) ... 

The vapor pressure of chlorine dioxide, Cl02, is 155 Torr at —22.75°C and 485 Torr at ().()0°C. Calculate (a) the standard enthalpy of vaporization (b) the standard entropy of vaporization (c) the standard Gibbs free energy of vaporization (d) the normal boiling point of C102. 

The enthalpy of formation of YF3 was determined by Rudzitis, Feder, and Hubbard 164) using fluorine bomb calorimetry. NdCla was done by solution methods (179), and the enthalpies of formation of LaFs and PrFa were determined by Polyachenok 161) who employed an indirect equilibration technique. A recent torsion-effusion study of the vapor pressure of CeFs 115) yields second and third law values for the enthalpy of sublimation. The thermodynamics of the chlorination of rare earths with gaseous chlorine have also been investigated 144). Gibbs energies of formation were determined for CeClg by solid-state electromotive force techniques 41). 

This table lists standard enthalpies of formation AH°, standard third-law entropies S°, standard free energies of formation AG°, and molar heat capacities at constant pressure, Cp, for a variety of substances, all at 25 C (298.15 K) and 1 atm. The table proceeds from the left side to the right side of the periodic table. Binary compounds are listed under the element that occurs to the left in the periodic table, except that binary oxides and hydrides are listed with the other element. Thus, KCl is listed with potassium and its compounds, but CIO2 is listed with chlorine and its compounds. 

Vapour pressures of sohd and hquid thorinm tetrachloride were measured at 880-1024, 1055 -1126 K by the transpiration techniqne and from 923 -1043, 1045 -1161 K by the boiling point method. The ThCLt nsed was prepared from thorium hydride and chlorine gas at 500 K, and pnrified by vacnnm distillation at 1000 K. The analysed Th/Cl ratio was reported to be 1/4. The container for both techniques was sihca, which could perhaps have reacted with ThCLt to form ThOCp. However, the results from the two techniques are self-consistent and agree well with those by [1939FIS/GEW2] and [1989LAU/HIL]. The melting temperatnre and enthalpy of fusion of ThCp were evaln-ated from the vapom pressure curves to be 1043 K, and (62.1 + 3.7) kJ-moF, respectively. 

Stream Information. Directed arcs that represent the streams, with flow direction from left to right wherever possible, are numbered for reference. By convention, when streamlines cross, the horizontal line is shown as a continuous arc, with the vertical line broken. Each stream is labeled on the PFD by a numbered diamond. Furthermore, the feed and product streams are identified by name. Thus, streams 1 and 2 in Rgure 3.19 are labeled as the ethylene and chlorine feed streams, while streams 11 and 14 are labeled as the hydrogen chloride and vinyl-chloride product streams. Mass flow rates, pressures, and tempera-mres may appear on the PFD directly, but more often are placed in the stream table instead, for clarity. The latter has a column for each stream and can appear at the bottom of the PFD or as a separate table. Here, because of formatting limitations in this text, the stream table for the vinyl-chloride process is presented separately in Table 3.6. At least the following entries are presented for each stream label, temperature, pressure, vapor fraction, total and component molar flow rates, and total mass flow rate. In addition, stream properties such as the enthalpy, density, heat capacity, viscosity, and entropy, may be displayed. Stream tables are often completed using a process simulator. In Table 3.6, the conversion in the direct chlorination reactor is assumed to be 100%, while that in the pyrolysis reactor is only 60%. Furthermore, both towers are assumed to carry out perfect separations, with the overhead and bottoms temperatures computed based on dew- and bubble-point temperatures, respectively. 

The pressure-enthalpy chart of Fig. 9.26 shows the course of a typical process. Line AC represents the boiling of the refrigerant under the influence of the process load. This takes place in the first exchanger referred to above. From the viewpoint of one following the chlorine flow, this is a liquefier. From the viewpoint of one following the refrigerant flow, and in common refrigeration industry parlance, it is an evaporator. 

Combining assumptions, the partial pressure of water in equilibrium with the hydrate at the quadruple point is equal to the vapor pressure of water at that temperature. The effect of temperature is then taken from an estimate of the enthalpy of sublimation. For ice, this is 12.15 kcal mol. From (3) above, the same property of the hydrate is obtained by adding 0.36 kcal mol . This gives 12.5, and the equation for the vapor pressure of chlorine hydrate (in atmospheres) becomes... 

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