Sodium gases

Sodium atoms must be removed from the solid to form sodium gas. Energy must be supplied to do this because, as we describe in Chapter 11. interatomic forces hold the atoms together in the solid metal. The tabulated value for the enthalpy of vaporization of Na is 107.5 kJ/mol. As described in Chapter 6, at 298 K the energy of vaporization is 2.5 kJ/mol less than this ... 

In a lamp filled with sodium gas, a voltage applied to electrodes at either end of the tube causes electrons to detach from the anode and accelerate toward the cathode. The electrons collide with the sodium vapor atoms, providing the energy for electrons within the sodium atoms to jump to higher levels. The atoms rapid decay back to their ground state, with the simultaneous emission of photons, is called D-line emission simply because of an early alphabetical designation for various solar spectral lines observed by the German physicist Joseph von Fraunhofer (1787-1826). 

In a lamp filled with sodium gas, a voltage applied to electrodes at either end of the tube causes electrons to accelerate across the tube, exciting the gas that then emits photons of light. 

Low-Pressure Sodium Lamp - A type of lamp that produces light from sodium gas contained in a bulb operating at a partial pressure of 0.13 to 1.3 Pascal. The yellow light and large size make them applicable to lighting streets and parking lots. 

Step 2 involves the formation of sodimn ion from solid sodimn, which is just the heat of formation for sodium gas and the first ionization energy for sodium (Appendix C and Figure 7.10 hst numbers for these processes) ... 

Example 3-8. The yellow D lines, with wavelengths 589.0 and 589.6 nm, are emitted by sodium gas when it is excited by an electric discharge. The rate at which the D lines are emitted has been determined by measuring the intensity of the lines as absorption lines in sodium gas. It is such as to correspond to a mean life of the excited states of 1.6 X lO" s. (Most excited states of atoms have about this mean life.) Does this value of the mean life lead to a broadening of the spectral lines ... 

The problems remain in a sodium-water accident. In a near term design, a double-wall tube is introduced into the steam generator (SG) a plate type heat exchanger is proposed instead of the ordinary SG for an advanced design. This new type SG is similar to the double-wall-tube SG as comes to layer configuration both SGs have three layers sodium, gas and steam/water. Sodium and steam/water are separated by double boundaries helium gas is generally used because of its good heat conductivity. 

Write reactions for formation of sodium vacancies in NaCl by exchange with a) chlorine gas and b) sodium gas. 

Figure 3.3 Concept of sodium gas heat exchanger for ASTRID.

In the ASTRID project, different power conversion systems (PCSs) are investigated based on the classical steam/water Rankine cycle and on an innovative gas (pure nitrogen) Brayton cycle. It is mainly motivated by enhanced safety and public acceptance with the practical elimination of the sodium/water reaction risk [22]. In this gas PCS, the main innovative component is the compact sodium gas heat exchanger (SGHE),... 

Figure 17.4 Photographs of machined plates for compact a sodium gas heat exchanger [22],...

O. Gastaldi, G. Laffont, Stams of the sodium gas heat exchanger (SGHE) development for the nitrogen power conversion system planned for the ASTRID SFR prototype, in Proceedings of ICAPP 2015, Paper 15362, Nice, France, 2015. 

SNG Substitute natural gas. soaps Sodium and potassium salts of fatty acids, particularly stearic, palmitic and oleic acids. Animal and vegetable oils and fats, from which soaps are prepared, consist essentially of the glyceryl esters of these acids. In soap manufacture the oil or fat is heated with dilute NaOH (less frequently KOH) solution in large vats. When hydrolysis is complete the soap is salted out , or precipitated from solution by addition of NaCl. The soap is then treated, as required, with perfumes, etc. and made into tablets. 

As shown in Table 2.4, atomic absorption is extremely sensitive. It is particularly suited to the analyses of arsenic and lead in gasolines, for sodium in fuel oils (where it is the only reliable method) and for mercury in gas condensates. 

An excellent example of work of this type is given by the investigations of Benson and co-workers [127, 128]. They found, for example, a value of = 276 ergs/cm for sodium chloride. Accurate calorimetry is required since there is only a few calories per mole difference between the heats of solution of coarse and finely divided material. The surface area of the latter may be determined by means of the BET gas adsorption method (see Section XVII-5). 

Brunauer and co-workers [129, 130] found values of of 1310, 1180, and 386 ergs/cm for CaO, Ca(OH)2 and tobermorite (a calcium silicate hydrate). Jura and Garland [131] reported a value of 1040 ergs/cm for magnesium oxide. Patterson and coworkers [132] used fractionated sodium chloride particles prepared by a volatilization method to find that the surface contribution to the low-temperature heat capacity varied approximately in proportion to the area determined by gas adsorption. Questions of equilibrium arise in these and adsorption studies on finely divided surfaces as discussed in Section X-3. 

Davis K B, Mewes M-0, Andrews M R, van Druten N J, Durfee D S, Kurn D M and Ketterle W 1995 Bose-Einstein oondensation in a gas of sodium atoms Phys.Rev.Lett. 75 3969-73... 

The table contains vertical groups of elements each member of a group having the same number of electrons in the outermost quantum level. For example, the element immediately before each noble gas, with seven electrons in the outermost quantum level, is always a halogen. The element immediately following a noble gas, with one electron in a new quantum level, is an alkali metal (lithium, sodium, potassium, rubidium, caesium, francium). 

To date there is no evidence that sodium forms any chloride other than NaCl indeed the electronic theory of valency predicts that Na" and CU, with their noble gas configurations, are likely to be the most stable ionic species. However, since some noble gas atoms can lose electrons to form cations (p. 354) we cannot rely fully on this theory. We therefore need to examine the evidence provided by energetic data. Let us consider the formation of a number of possible ionic compounds and first, the formation of sodium dichloride , NaCl2. The energy diagram for the formation of this hypothetical compound follows the pattern of that for NaCl but an additional endothermic step is added for the second ionisation energy of sodium. The lattice energy is calculated on the assumption that the compound is ionic and that Na is comparable in size with Mg ". The data are summarised below (standard enthalpies in kJ) ... 

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