Gaseous oxygen

KrF+ AsF/, KrF+ SbF/, and KrF+ Sb2F, are moderately stable at room temperature. The KrF+ cation ranks as the most powerful chemical oxidizer known (120) and is capable of oxidizing gaseous xenon to XeF/, gaseous oxygen to O2, NF to NF, and chlorine, bromine, and iodine pentafluorides to... 

Coke gasification occurs just outside the raceway area where gaseous oxygen is no longer available to completely combust the CO to CO2. This reaction goes essentially to completion at temperatures between 1500 to 2100°C. The net heat effect is exothermic, as shown in equation 1. The endothermic equation (eq. 2) allows control of the temperature in front of the tuyeres by controlling the moisture in the hot blast. 

The superoxides compare well with a combination of Hquid oxygen or gaseous oxygen systems and a CO2 scmbber, eg, LiOH. Heat release is somewhat less than the combination system, and the volume of superoxides which is required is roughly equivalent to that of lithium hydroxide. 

The use of oxygen compounds, eg, gaseous oxygen, ozone (qv), and hydrogen peroxide (qv), is becoming more important. 

A jet of gaseous oxygen is blown at high velocity onto the surface of a bath of molten pig iron and scrap at the bottom of the furnace by a vertical water-cooled retractable lance iaserted through the mouth of the vessel (Fig. 4). The furnace is mounted ia a tmnnion ring and can be tilted backward or forward. 

In the cycle shown, gaseous oxygen and nitrogen are withdrawn at room temperature. Liquid oxygen could be withdrawn from point A and liquid nitrogen from point E, but in this case more refrigeration would oe needed. 

The blue colour of oxygen in the liquid and solid phases is due to electronic transitions by which molecules in the triplet ground state are excited to the singlet states. These transitions are normally forbidden in pure gaseous oxygen and, in any case, they occur in the infrared region of the spectrum at 7918 cm" ( Ag) and 13 195 cm" ( ]+). However, in the condensed phases a... 

As the system passes from the active to the passive state the initial interaction depends on the composition of the aqueous phaseAn initial chemisorbed state on Fe, Cr and Ni has been postulated in which the adsorbed oxygen is abstracted from the water molecules. This has features in common with the metal/gaseous oxygen interaction mentioned previously. With increase in anodic potential a distinct phase oxide or other film substance emerges at thicknesses of 1-4 nm. Increase in the anodic potential may lead to the sequence... 

Fig. 7.84 Free energy diagram for a binary system consisting of metal M and gaseous oxygen O2 at a temperature of 1 000 K...

Allotropy is a very common phenomenon shown by metals, metalloids, and nonmetals. In the gaseous or liquid state, allotropes most often differ from one another in molecular formula. Consider, for example, the two allotropes of gaseous oxygen, 02, and ozone, 03. 

Thermal treatment of the compounds obtained from the hydrolysis leads to their decomposition, yielding tantalum or niobium oxides and gaseous oxygen. The processes of thermal decomposition are given as follows [512] ... 

In the first cell the net reaction is the production of metallic mercury and gaseous oxygen through electrolysis of aqueous mercuric nitrate ... 

Pt is attacked by bromine trifluoride at 280° in the presence of K fluoride (Ref 5). Finely divided Pt and some other metals will cause a mixt of Hj and 02 to explu at ordinary temps (Ref 1). A little Pt black dropped into a hydrogen peroxide soln can cause an expln (Ref 2). Pt and molten Ii react violently at 540° 20° (Ref 7), and an incandescent reaction occurs when it is wanned gently in gaseous oxygen difluoride (Ref 6). The decompn of 92% per-monosulfuric acid is expl in the presence of smooth or finely divided Pt (Ref 3). The re-. acting mass formed by the mixt of P and Pt can become incandescent when heated (Ref 8). Dry, used Pt catalyst has exWd while being screened (Ref 4)... 

Figure 4.43. Thermal desorption spectra after gaseous oxygen adsorption on a Pt film deposited on YSZ at 673 K and an 02 pressure of 4x 10"6 Torr for 1800 s (7.2 kL) followed by electrochemical O2 supply (I=+15 pA) for various time periods.29-30 Reprinted from ref. 30 with permission from Academic Press.

These important conclusions are not limited to Pt/YSZ only. Similar is the behaviour of Ag/YSZ31,119 (Fig. 4.44) and Au/YSZ.119 In the last case actually gaseous oxygen adsorption is negligible.119... 

Figure 5.21. Experimental setup (inset) showing the location of the working (WE), counter (CE) and reference (RE) electrodes and of the heating element (HE) thermal desorption spectra after gaseous oxygen dosing at 673 K and an 02 pressure of 4x1 O 6 Torr on Pt deposited on YSZ for various exposure times. Oxygen exposure is expressed in kilo-langmuirs (1 kL=l0 3 Torrs). Desorption was performed with linear heating rate, ()=1 K/s.4 S Reprinted with permission from Academic Press.

In a broad sense similar effective double layers can be formed via gaseous adsorption or evaporation (e.g. Na evaporated on Pt electrodes deposited on fT-A Ch has been shown to behave similarly to electrochemi-cally supplied Na). In other cases, such as the effective double layer formed upon anodic polarization of Pt deposited on YSZ, the electrochemically created effective double layer appears to be unique and cannot be formed via gaseous oxygen adsorption at least under realistic (<300 bar) oxygen pressure conditions. 

On the other hand, the electrochemical potentials of electrons, pe, oxygen ions, jIo2, and gaseous oxygen, po2 are related via the charge transfer equilibrium at the three-phase-boundaries (tpb) metal-support-gas38"40 ... 

Selective oxidation and ammoxldatlon of propylene over bismuth molybdate catalysts occur by a redox mechanism whereby lattice oxygen (or Isoelectronlc NH) Is Inserted Into an allyllc Intermediate, formed via or-H abstraction from the olefin. The resulting anion vacancies are eventually filled by lattice oxygen which originates from gaseous oxygen dlssoclatlvely chemisorbed at surface sites which are spatially and structurally distinct from the sites of olefin oxidation. Mechanistic details about the... 

The OH radicals produced, having no independent existence, react with one another forming water and oxygen. Gaseous oxygen is thus evolved at the anode ... 

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