Deuterium physical properties

The slightly different physical properties of deuterium allow its concentration in ordinary hydrogen (or the concentration of a deuterium-containing compound in a hydrogen compound) to be determined. Exchange of deuterium and hydrogen occurs and can be used to elucidate the mechanism of reactions (i.e. the deuterium is a non-radioactive tracer). Methanol exchanges with deuterium oxide thus ... 

Because it was not possible to explain the differences in the effectiveness of hydrogen as compared to other gases on the basis of differences in their physical properties, ie, thermal conductivity, diffusivity, or heat capacity differences, their chemical properties were explored. To differentiate between the hydrogen atoms in the C2H2 molecules and those injected as the quench, deuterium gas was used as the quench. The data showed that although 90% of the acetylene was recovered, over 99% of the acetylene molecules had exchanged atoms with the deuterium quench to form C2HD and... 

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).

The thermal conductivity of gas-phase deuterium is about 0.73 times that of gas-phase hydrogen. This thermal conductivity difference offers a convenient method for analysis of H2—D2 mixtures. Other physical properties of D2, T2, HD, DT, and HT are Hsted in the Hterature (60). 

Table 3.2 Physical properties of hydrogen, deuterium and tritium...

Because isotopes of the same element have the same number of protons and the same number of electrons, they have essentially the same chemical and physical properties. However, the mass differences between isotopes of hydrogen are comparable to the masses themselves, leading to noticeable differences in some physical properties and slight variations in some of their chemical properties. Hydrogen has three isotopes (Table B.2). The most common ( H) has no neutrons so its nucleus is a lone proton. The other two isotopes are less common but nevertheless so important in chemistry and nuclear physics that they are given special names and symbols. One isotope (2H) is called deuterium (D) and the other ( H) is called tritium (T). 

The method using GC/MS with selected ion monitoring (SIM) in the electron ionization (El) mode can determine concentrations of alachlor, acetochlor, and metolachlor and other major corn herbicides in raw and finished surface water and groundwater samples. This GC/MS method eliminates interferences and provides similar sensitivity and superior specificity compared with conventional methods such as GC/ECD or GC/NPD, eliminating the need for a confirmatory method by collection of data on numerous ions simultaneously. If there are interferences with the quantitation ion, a confirmation ion is substituted for quantitation purposes. Deuterated analogs of each analyte may be used as internal standards, which compensate for matrix effects and allow for the correction of losses that occur during the analytical procedure. A known amount of the deuterium-labeled compound, which is an ideal internal standard because its chemical and physical properties are essentially identical with those of the unlabeled compound, is carried through the analytical procedure. SPE is required to concentrate the water samples before analysis to determine concentrations reliably at or below 0.05 qg (ppb) and to recover/extract the various analytes from the water samples into a suitable solvent for GC analysis. 

Deuterium, 8 456—485 13 759. See also Canadian Deuterium Uranium (CANDU) reactors analytical methods, 8 467-468 economic aspects, 8 467 health and safety factors, 8 461-462 physical properties, 8 457-462, 459t production of heavy water, 8 459t, 462-467... 

Isotopes of hydrogen. Three isotopes of hydrogen are known H, 2H (deuterium or D), 3H (tritium or T). Isotope effects are greater for hydrogen than for any other elements (and this may by a justification for the different names), but practically the chemical properties of H, D and T are nearly identical except in matters such as rates and equilibrium constants of reactions (see Tables 5.1a and 5.1b). Molecular H2 and D2 have two forms, ortho and para forms in which the nuclear spins are aligned or opposed, respectively. This results in very slight differences in bulk physical properties the two forms can be separated by gas chromatography. 

As tritium is used only in tracer proportions, only the physical properties of deuterated sugars (into which the deuterium is usually introduced at 100% abundance) are of interest. Many of these properties have been discussed in Section IV, as they are very useful for localizing the deuterium. 

To study the N-1 phase transition, it is necessary to find some physical property proportional to 5(7) that can be measured accurately as a function of temperature. There are many possibilities, which include depolarization of Raman spectra, diamagnetic susceptibility anisotropy, NMR deuterium quadrupole splitting, dielectric constant... 

Denterinm is invariably prepared from heavy water, which itself is mannfactnred by the electrolytic emichment of water, and is available for use as a moderator in nuclear reactors. D2O is useful as a source of deuterium in deuterium-labeled compounds. Deuterium compounds such as heavy water have been extensively studied. In Table 3, a number of physical properties of normal water and heavy water are compared. 

The 10% mass change in water by the replacement of protium by deuterium results in substantial changes in many commonly known properties of water. In Table 3, a number of physical properties of normal water, FI2O, and heavy water, D2O, are compared. The viscosity of D2O is 25% higher than that of H2O at 25 °C, which is the most conspicuous difference between H2O and D2O. 

Natural waters formed of —99.7% of H2 0 are also constituted of other stable isotopic molecules, mainly H2 0 (—2%o), H2 0 ( 0.5%o), and HD 0 (—0.3%c), where H and D (deuterium) correspond to and H, respectively. Owing to slight differences in physical properties of these molecules, essentially their saturation vapor pressure, and their molecular diffusivity in air, fractionation processes occur at each phase change of the water except sublimation and melting of compact ice. As a result, the distribution of these water isotopes varies both spatially and temporally in the atmosphere, in the... 

The physical properties of isotopes differ slightly because of differences in atomic mass. For example, water that contains deuterium is called heavy water because the neutrons in deuterium add mass to the water molecule. Some nuclear reactors use heavy water to help keep the chain reaction going. The heavy water slows down (or moderates) the neutrons produced during nuclear fission so that they can be absorbed by the uranium fuel. You will learn more about nuclear reactions in Chapter 25. 

Although hydrogen and deuterium have similar physical properties, their nuclear properties are markedly different. 

In another experiment236 it was found that the decomposition of acetylene in both hydrogen and deuterium was identical and low relative to He, Ar or N2 suggesting that physical properties such as thermal conductivity, diffusivity or heat capacity of the quench were not the reason for the acetylene-preservation in hydrogen. Mass... 

An expression will be derived for the dependence of a on the physical properties of the water-hydrogen sulfide system, temperature and pressure. The slight dependence of a on deuterium content will be neglected by considering only low deuterium abundances, at which D,0 In this limiting case, the expression for a reduces to... 

Katz, J. J., in Chemical and Biological Studies with Deuterium, Pennsylvania State Univ., 1965 (physical properties and isotope effects including biological effects). 

Combined effects. Because temperature, pressure and solution composition all affect the physical properties of water, these three variables can act in concert to influence fractionation factors (Horita et al., in press Hu and Clayton, in press). Increases in pressure and NaCl concentration both work to decrease the fluid s affinity for deuterium. The isotopic effect is most pronounced at low pressures and NaCl concentrations, which relates to the fact that the largest changes in the density of the fluid occurs over this region of pressure-composition space. It appears that the fractionation factor and the density of aqueous NaCl solutions are closely related to each other. With additional systematic experiments, empirical equations can be designed that relate the isotope salt effects and the density of aqueous solutions. 

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