Sodium vapor pressure

In Figure 5, a speculative version of a phase diagram for the system Na WOs is shown, including the possible peritectoid isotherm. In this temperature region it is clear that the system is no longer pseudobinary, so that verification of the possibility shown here requires some control of the sodium vapor pressure. The eutec-... 

Figure 2. Experimentai emission spectra of a high-pressure Na discharge. The tube diameter is 7.6 mm, the axis temperature 3000 K, the wall temperature 1400-1800 K, and the sodium vapor pressure 100 (a), 300 (b) and 1000 (c) torr. The spectra have not been corrected for the instrument spectral sensitivity indicated by -----. Arrows 1 and 2 indicate the classical satellites. A number of Na nonresonance lines and the K and Cs resonance lines (due to trace impurities) are indicated.

Figure 4. Experimental spectrum of the reduced absorption coefficient k/[NaP, from Ref. 12. The spectrum was constructed from absorption spectra measured for sodium vapor pressures in between 100 and 1000 torr. The error bar indicates the absolute accuracy of this procedure (relative errors are considerably smaller). The Na nonresonance lines and the K and Cs resonance lines (see Fig. 2) were omitted.

Low-pressure sodium lamps (sodium vapor pressure 0.5 Pa). 

Low-pressure sodium lamps have a sodium vapor pressure of 0.7 Pa at 260 °C. How many micrograms of Na must evaporate at 260 °C to yield a pressure of 0.7 Pa in a 27-mL bulb ... 

Pressure within the channel due to the formation of sodium vapor was estimated to be of the order of 300 psi based on sodium vapor pressure at the maximum coolant temperature. Extreme deformation of the hexagonal channel into a cylinder of equivalent volume, and then ultimate rupture of this shape require an inner-channel pressure of approximately 750 psi, if the channel material is near the boiling point of sodium. This, of course, assumes that the adjacent channels offer no restraint. Complete circular deformation of the channel would cause a maximum interference of approximately in. with an adjacent channel. This interference would be localized and probably accommodated by local deformation in an adjacent channel without seriously disrupting coolant flow. 

Liquid Metals. If operating temperatures rise above 250—300°C, where many organic fluids decompose and water exerts high vapor pressure, hquid metals have found some use, eg, mercury for limited appHcation in turbines sodium, especially its low melting eutectic with 23 wt % potassium, as a hydrauhc fluid and coolant in nuclear reactors and potassium, mbidium, cesium, and gallium in some special uses. 

Niobium is used as a substrate for platinum in impressed-current cathodic protection anodes because of its high anodic breakdown potential (100 V in seawater), good mechanical properties, good electrical conductivity, and the formation of an adherent passive oxide film when it is anodized. Other uses for niobium metal are in vacuum tubes, high pressure sodium vapor lamps, and in the manufacture of catalysts. 

FIG. 2-29 Enthalpy-concentration diagram for aqueous sodium hydroxide at 1 atm. Reference states enthalpy of liquid water at 32 F and vapor pressure is zero partial molal enthalpy of infinitely dilute NaOH solution at 64 F and 1 atm is zero. [McCahe, Trans. Am. Inst. Chem. Eng., 31, 129(1935).]... 

This reasoning is confirmed experimentally. Compare, for example, the vapor pressure lowerings for 1.0 M solutions of glucose, sodium chloride, and calcium chloride at 25°C. 

The freezing points of electrolyte solutions, like their vapor pressures, are lower than those of nonelectrolytes at the same concentration. Sodium chloride and calcium chloride are used to lower the melting point of ice on highways their aqueous solutions can have freezing points as low as —21 and — 55°C, respectively. 

A 1.500-g sample containing sodium nitrate was heated to form NaN02 and 02. The oxygen evolved was collected over water at 23°C and 752 mm Hg its volume was 125.0 mL. Calculate the percentage of NaN03 in the sample. The vapor pressure of water at 23°C is 21.07 mm Hg. 

The reduction of K2TaF7 can also be performed using sodium vapors [584]. This process is conducted at an Na pressure as low as 0.1 torr, which enables the removal of interferring gases such as N, O and H20. The interaction begins at 350°C. The temperature further increases up to 800°C to prevent the condensation of sodium and the formation of colloidal tantalum powder. The product of the interaction is removed from the reactor after cooling and treated with boiled HC1 and HF solutions. The method enables the production of coarse grain tantalum powder with 99.5% purity. 

The relation between moisture content and vapor pressure (or relative humidity) at constant temperature is expressed by an isotherm. Figures 1 and 2 show typical isotherms for a crystalline hydrate sodium carbonate and a food material (potato). 

The only parts of Fig. 5 which can meaningfully be described as solubility in a compressed gas are WX and XV. However, a very different situation arises if the saturated vapor pressure curve cuts the critical curve (M—N of Fig. 3). Figure 4 shows that this does not happen for the three sodium halides. The complete course of the critical curve is not known, but enough is known in the case of the sodium chloride system51 75 for it to be clear that it rises well above the maximum of the saturated vapor pressure curve. However, it is cut by the vapor pressure curves of less soluble salts such as sodium carbonate and sodium sulphate.40 87 The (p, T) projection of a system of the type water + sodium chloride is... 

The continuous sintering is mainly a zone sintering process in which the electrolyte tube is passed rapidly through the hot zone at about 1700 °C. This hot zone is small (about 60 mm) in zone sintering, no encapsulation devices are employed. The sodium oxide vapor pressure in the furnace is apparently controlled by the tubes themselves. Due to the short residence time in the hot zone, the problem of soda loss on evaporation can be circumvented. A detailed description of / "-alumina sintering is given by Duncan et al. [22]. 

Bonilla, C. F., D. L. Sawhuey, and N. M. Makansi, 1962, Vapor Pressure of Alkali Metals III, Rubidium, Cesium, and Sodium-Potassium alloy up to 100 psia, Proc. 1962 High Temperature Liquid MetaI Heat Transfer Tech. Meeting, BNL-756, Brookhaven, NY. (3)... 

Larabee, C.E., Jr. and Sprague, E.D. (1986) Aggregation of sodium undecanoate and sodium 10-undecenoate in water at 37 °C vapor pressure osmometry. Journal of Colloid and Interface Science, 114 (1), 256-260. 

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