Carbon , thermodynamic properties

JANAE U.S. Department of Commerce National Institute of Standards and Technology chemical thermodynamic properties of inorganic substances and of organic substances containing only one or two carbon atoms... 

Physica.1 Properties. Carbonyl sulfide [463-58-1] (carbon oxysulfide), COS, is a colorless gas that is odorless when pure however, it has been described as having a foul odor. Physical constants and thermodynamic properties are Hsted ia Table 1 (17,18). The vapor pressure has been fitted to an equation, and a detailed study has been made of the phase equiUbria of the carbonyl sulfide—propane system, which is important ia the purification of propane fuel (19,20). Carbonyl sulfide can be adsorbed on molecular sieves (qv) as a means for removal from propane (21). This approach has been compared to the use of various solvents and reagents (22). 

Some values of physical properties of CO2 appear in Table 1. An excellent pressure—enthalpy diagram (a large Mohier diagram) over 260 to 773 K and 70—20,000 kPa (10—2,900 psi) is available (1). The thermodynamic properties of saturated carbon dioxide vapor and Hquid from 178 to the critical point,... 

The physical and thermodynamic properties of carbon monoxide are well documented in a number of excellent summaries (1 8). The thermochemical data cited here are drawn predominantly from references 1—3 physical property data from reference 5. A summary of particularly useful physical constants is presented in Table 1. 

Values for the free energy and enthalpy of formation, entropy, and ideal gas heat capacity of carbon monoxide as a function of temperature are listed in Table 2 (1). Thermodynamic properties have been reported from 70—300 K at pressures from 0.1—30 MPa (1—300 atm) (8,9) and from 0.1—120 MPa (1—1200 atm) (10). 

Computes thermodynamic properties of air, argon, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, water vapor, and products of combustion for hydrocarbons. Computes all properties from any two independent properties. 

THERMOSIM Module 1 EQUIL Gulf Publishing Company, Book Division Melissa Beck P.O. Bo 2608 Houston, TX 77252 (713) 520-4444 Database of thermodynamic properties of 200 hydrocarbons, 9 non-bydrocaibon gases, carbon, and sulfur. Requires 512K memory and 2 disk drives. 

The thermodynamic properties of a chemical substance are dependent upon its state and, therefore, it is important to indicate conditions when writing chemical reactions. For example, in the burning of methane to form carbon dioxide and water, it is important to specify whether each reactant and product are solid, liquid, or gaseous since different changes in the thermodynamic property will occur depending upon the state of each substance. Thus, different volume and energy changes occur in the reactions... 

When the metal can form a stable carbide, the product of the carbothermic reduction of its oxide may be a carbide instead of the metal itself. The question as to whether a carbide or the metal forms under standard conditions when the oxide is reduced by carbon is not answered by the Ellingham diagram. To obtain an answer to this question, a more detailed consideration of the thermodynamic properties of the system is necessary. 

It was shown in the previous section that different relatively stable conformations of a given molecule can result from internal rotation of a particular functional group. The possibility of the existence of various conformers is of extreme importance in many applications. It should be noted, for example, that the biological activity of an organic molecule often depends on its confonfia-tion - in particular the relative orientation of a specific functional grtmp. As another example, the thermodynamic properties of, say, an alkane are directly related to the conformation of its carbon skeleton. In this context the industrial importance of /sooctane is well-known. 

However, since the standard state of carbon is the condensed state, carbon graphite, the only partial pressure it exerts is its vapor pressure (pw), a known thermodynamic property that is also a function of temperature. Thus, the preceding formation expression is written as... 

In the previous discussion of laminar and turbulent flames, the effects of the physical and chemical parameters on flame speeds were considered and the trends were compared with the experimental measurements. It is of interest here to recall that it was not possible to calculate these flame speeds explicitly but, as stressed throughout this chapter, it is possible to calculate the detonation velocity accurately. Indeed, the accuracy of the theoretical calculations, as well as the ability to measure the detonation velocity precisely, has permitted some investigators to calculate thermodynamic properties (such as the bond strength of nitrogen and heat of sublimation of carbon) from experimental measurements of the detonation velocity. 

Sverjensky DA, Shock EL, Helgeson HC (1997) Prediction of flie thermodynamic properties of aqueous metal complexes to 1000°C and 5 kb. Geochim Cosmochim Acta 61 1359-1412 Tarutani T, Clayton RN, Mayeda TK (1969) The effect of polymorphism and magnesium substitution on oxygen isotope fractionation between calcium carbonate and water. Geochim Cosmochim Acta 33 987-996... 

Garcia Baonza, V., Fernandez Rnbio, J.E., Caceres Alonso, M. and Niinez Delgado, J. Thermodynamic properties of liqnid carbon disulfide, J. Chem. Thermodyn., 25(4) 555-559, 1993. 

Hill, J.O., Worsley, EG., and L.G. Hepler. Calorimetric determination of the distribution coefficient and thermodynamic properties of bromine in water and carbon tetrachloride, J. Phys. Chem., 72(10) 3695-3697, 1968. 

There are few reported analyses of the thermodynamics of carbon deposition in the ATR of liquid fuels. Though typically not stated in these analyses, the calculations were presumably carried out using the thermodynamic properties of elemental carbon e.g., as formed in reactions (6)-(8) above), rather than any coke species (which consist of a wide range of polynuclear aromatic compounds with quite different thermodynamic properties). This is an important difference, since the results apply only to elemental carbon, not coke deposition in general. 

Using the same procedure, spherical nanosize particles of hematite were coated with yttrium basic carbonate and showed that various surface thermodynamic properties of these systems were essentially those of yttria (37). 

Thermochemical attention in this chapter is directed towards compounds with carbon—zinc bonds, i.e. species that are usually labeled organometallic. The thermodynamic properties that we discuss are restricted to the enthalpy of formation (often called the heat of formation ), enthalpy of vaporization and carbon—zinc bond energies. We forego discussion of other thermochemical properties such as entropy, heat capacity or excess enthalpy. The energy units are kJmoU where 4.184 kJ is defined to equal 1 kcal. 

Matrix isolation methods of synthesis have also been used to prepare and study coordination compounds. These involve the vaporization of a metal and a potential ligand, which are then rapidly carried in a stream of inert gas to a very cold surface, where the compound which has been formed is quickly trapped in the solid matrix. It is possible to determine the type of bonding, the structure and the thermodynamic properties of the compounds formed. Only small ligand molecules have been used thus far carbon monoxide, nitric oxide, nitrogen and oxygen, for example, but molecules of great interest have been formed. Some such are [Pd(C2H4)], [Pd(N2)3], [Ni(N2)202], [Ni(N2)4] and [Ni(CO)(N2)3].41... 

It is possible to compare direct measurements of relative stabilities of isomeric ions with comparisons of nonisomeric ions by use of a group additivity scheme. Group additivity schemes have been developed by Benson for heats of formation (and other thermodynamic properties) of organic molecules in the gas phase,40 and by Guthrie to represent free energies of formation in aqueous solution.38 In both cases, energies of unstrained hydrocarbons accurately correspond to a sum of contributions from primary, secondary, tertiary, and quaternary carbons CH3, CH2, CH, and C. 

The six parameters defining the kinetic and thermodynamic properties of tautomerization reactions that have been determined for a representative selection of carbon acids are collected in Table 1. The column headed by the symbol contains the observed pH-independent, uncatalyzed terms, k c=kf +, of the ketonization rate law [Equation (8)]. In general,... 

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