摘要:

A fundamental equation of state for the Helmholtz free energy of R-32 (difluoromethane) is presented which is valid from the triple point at 136.34 K to 435 K and pressures up to 70 MPa. It is based on accurate measurements of pressure-density-temperature(p,&Vrgr;,T),speed of sound, heat capacity, and vapor pressure currently available. New values for the isobaric heat capacitycp&convolu;of the ideal gas calculated from spectroscopic data taking into account also first order anharmonicity corrections are presented. The Helmholtz free energy equation of state has 19 coefficients and represents all selected experimental data within their estimated accuracy with the exception for heat capacities and speed of sound in the region close to the critical point. Typical uncertainties are±0.05&percent;for density,±0.02&percent;for the vapor pressure and±0.5&percent;–1&percent;for the heat capacity. This equation of state has been compared to equations developed by other research groups by Annex 18 of the International Energy Agency and has been selected as an international standard formulation for the thermodynamic properties of R-32 by this group. ©1997 American Institute of Physics and American Chemical Society.

ISSN:0047-2689    

DOI:10.1063/1.556002

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

This paper updates and extends part of the previous data base of critical evaluations of the kinetics and photochemistry of gas-phase chemical reactions of neutral species involved in atmospheric chemistry [J. Phys. Chem. Ref. Data9, 295 (1980);11, 327 (1982);13, 1259 (1984);18, 881 (1989);21, 1125 (1992);26, 521 (1997)]. The present evaluation is limited to the following families of atmospherically important reactions:Ox,HOx,NOx,and SOx.The work has been carried out by the authors under the auspices of the IUPAC Subcommittee on Gas Phase Kinetic Data Evaluation for Atmospheric Chemistry. Data sheets have been prepared for 151 thermal and photochemical reactions, containing summaries of the available experimental data with notes giving details of the experimental procedures. For each thermal reaction, a preferred value of the rate coefficient at 298 K is given together with a temperature dependence where possible. The selection of the preferred value is discussed and estimates of the accuracies of the rate coefficients and temperature coefficients have been made for each reaction. For each photochemical reaction the data sheets list the preferred values of the photoabsorption cross-sections and the quantum yields of the photochemical reactions together with comments on how they were selected. The data sheets are intended to provide the basic physical chemical data needed as input for calculations which model atmospheric chemistry. A table summarizing the preferred rate data is provided, together with an appendix listing the available data on enthalpies of formation of the reactant and product species. ©1997 American Institute of Physics and American Chemical Society.

ISSN:0047-2689    

DOI:10.1063/1.556010

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The errata are arranged in the format shown below and are listed as found according to successive pages in the 1996 publication, J. Phys. Chem. Ref. Data25, 1–525 (1996). After the page number for a specific erratum, which is shown on the extreme left side of the first line, information is provided regarding its location on a given page, such as: compound formula, compound name, reference squib, or other pertinent information. On the second line, the erratum appears as found in the publication. On the third line, one finds the correction. The last line offers a comment or explanation about the erratum. ©1997 American Institute of Physics and American Chemical Society.

ISSN:0047-2689    

DOI:10.1063/1.556003

出版商:AIP    

年代:1997

数据来源: AIP