An empirical fundamental equation of state (EOS) is presented for fluid heavy water (deuterium oxide, D 2 O). The equation is explicit in the reduced Helmholtz energy and allows the calculation of all thermodynamic properties over the whole fluid surface. It is valid from the melting-pressure curve up to a temperature of 825 K at pressures up to 1200 MPa. Overall, the formulation represents the most accurate measured values and almost all other available data within their experimental uncertainty. In the homogeneous liquid and vapor phase, the expanded relative uncertainties of densities calculated from the EOS are mostly 0.1% or less; liquid-phase densities at atmospheric pressure can be calculated with an uncertainty of 0.01%. The speed of sound in the liquid phase is described with a maximum uncertainty of 0.1%; the most accurate experimental sound speeds are represented within their uncertainties ranging from 0.015% to 0.02%. In a large part of the liquid region, the isobaric heat capacity is represented with an uncertainty of 1%. The uncertainty in vapor pressure is mostly within 0.05%. In the critical region, the uncertainties of calculated properties are in most cases higher than the values above, but the EOS enables a reasonable description of this region. The equation matches available data for the metastable subcooled liquid, and it extrapolates in a qualitatively correct way to extreme values of temperature and pressure. This formulation is the result of an effort to establish a new standard for the thermodynamic properties of heavy water by the International Association for the Properties of Water and Steam.

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A fundamental equation of state is presented for the calculation of thermodynamic properties of chlorine. It is expressed in terms of the Helmholtz energy with the independent variables temperature and density. Based on the available experimental data from the literature, the equation is valid from the triple point temperature 172.17-440 K with a maximum pressure of 20 MPa. The quality of the equation is evaluated by comparisons with experimental measurements. Since the equation was developed in part for use in mixture models relevant for carbon capture and storage applications, special focus was also given to correct extrapolation behavior. K E Y W O R D S chlorine, equation of state, Helmholtz energy, thermodynamic properties 1 | INTRODUCTION Knowledge of thermodynamic properties is essential for many processes in chemical and process engineering as well as academic research. For industrial use, the properties have to be as accurate as possible and, additionally, easily accessible. In order to fulfill these requirements, equations of state are used. These equations are correlated to thermodynamic properties obtained with experiments carried out in laboratories. Therefore, the accuracy and range of validity of the equation of state is limited to the accessibility as well as the quality of the experimental data. The availability of thermodynamic properties is often quite limited for fluids that are dangerous to handle, for example, because they are toxic, flammable, or reactive with materials that are mounted in the apparatus. In this article, a new equation of state is presented for chlorine.Chlorine was discovered accidentally by Carl Wilhelm Scheele in 1774 by bleaching leaves and flowers. Its name was given by Humphry Davy in 1810 who realized that in fact chlorine is an element. In the following centuries, it became a very important substance in many different processes, for example, it is used in water purification, bleaching, medicines, paper production, and organic chemistry. At standard conditions, it is a greenish-yellow gas with a very strong smell. Because of its binding propensity, it is highly reactive with many substances. It is rarely found as an element in nature, but rather in combination with other substances, for example, sodium chloride. It is not flammable and only explosive

This study reports new density measurements of the (CO2 + CO) system at temperatures from (283 to 373) K and pressures up to 48 MPa for four different mixtures, with compositions ranging from (5 to 50) mol% CO. A commercial vibrating-tube densimeter was used to measure the density of each mixture as a function of pressure and temperature. Temperature and pressure were measured with expanded uncertainties (k = 2) of 0.05 K and 0.035 MPa, respectively. The relative combined expanded uncertainty (k = 2) of the density was estimated to be between (0.2 and 1.8) %, with values ≤ 1 % for most state points. The new data significantly expand the pressure and composition ranges of the available density data for the (CO2 + CO) system. Together with recently published vapourliquid-equilibrium data, the new data enabled the development of an improved Helmholtz-energyexplicit mixture model. The new model is based on the mathematical approach of the GERG-2008 and EOS-CG models with new adjustable parameters. As a result, the new mixture model allows for a significantly more accurate description of the thermodynamic properties of the (CO2 + CO) system than GERG-2008 and EOS-CG. A detailed comparison among our density data, experimental data from the literature and the different mixture models is presented.

Wasserstoff hat eine Menge Vorzüge: Er kann sowohl als Energieträger als auch als Grundstoff verwendet werden. Er ist geruchslos und ungiftig, besitzt -auf die Masse bezogen -eine hohe Energiedichte, lässt sich gut transportieren und speichern -und bei seiner Verbrennung entsteht statt CO 2 nur Wasserdampf. All das macht ihn zum Hoffnungsträger für die klimaneutrale Transformation. Doch diesen vielen Vorteilen steht ein großer Nachteil entgegen: H 2 in Reinform kommt in der Natur kaum vor. Das bedeutet, er muss unter Energieeinsatz aus chemischen Verbindungen gewonnen werden. Die Verfahren, mit denen diese Gewinnung erfolgt, werden durch Farben gekennzeichnet.