Discharge in oxygen

Production of ozone by irradiation or electric discharge in oxygen is readily revealed by the characteristic odor. The yield, though, is not easy to establish. In a closed system, it is very small in a flow system, it increases with the flow rate and decreases with the dose rate. These have been explained by taking the formation reaction as a three-body combination with O atom, O + 202— 03 + 02 (no chain), where the back reaction is indeed a chain process (Magee and Burton, 1951). In the mass spectrometer, 02+ is the main ion but the total yield of excited states is about the same as that of ionization (about 3.1), giving the following initial species ... 

Ozone is commonly prepared by silent electric discharge in oxygen, which gives up to 10% 03. The gas is blue. Pure ozone can be obtained by fractional liquefaction of 02—03 mixtures. There is a two-phase liquid system the one with 25% of 03 is stable, but a deep purple phase with 70% of 03 is explosive, as is the deep blue pure liquid (bp -112°C). The solid (mp -193°C) is black violet. Small quantities of 03 are formed in electrolysis of dilute sulfuric acid, in some chemical reactions producing 02, and by the action of uv light on 02 the combination of certain peroxo radicals and some chemical reactions may also result in 03.19... 

Devins (18) assumed that the ozonizer discharges in oxygen studied by him may be regarded as similar to the more or less ideal plasma of the uniform positive column of a glow discharge because, in other experiments, Manley (52) found that, at atmospheric pressure, X/p is nearly independent of the alternating potential applied to the electrodes. 

In the last example above, the order with respect to the product O2 is -1. Negative orders often arise from reverse reactions in which products reform reactants, thereby slowing the overall reaction rate. Oxygen is present at the beginning of this reaction as commonly studied because ozone is made by an electrical discharge in oxygen gas. It is possible to study the kinetics of the decomposition of pure ozone. In the absence of oxygen, the initial rate law is quite different from the one listed in the above table. 

Figure 3. Variation of the relative abundance of different ions with pressure in a positive corona discharge in oxygen containing 2.0 X 10 2 mole % of water vapor. Discharge current is 1 X 10 8 amps./cm. length. Discharge potential varied between 630 and 750 volts...

Several investigations of ions in glow discharges in oxygen have been reported. 0+ and 02+ were reported by Knewstubb (52), Luhr (64), and Dickenson and Sayers (12). In addition, 03+ and 04+ (12) have been reported. 

Ozone occurs naturally in the atmosphere but in too low a concentration for convenient use. In the laboratory, ozone is produced by electric discharge in oxygen. Ozone is best viewed as a resonance species with four... 

In the biological area, spark source mass spectrometry (SSMS) is an ideal tool for trace elemental analysis. First, the sample is ashed by strong heating or by a microwave discharge in oxygen to remove the organic material. The residue is then... 

Table 8-8. Formation of Different Surfaee Groups by Functionalization of Carbon Nanotubes in Low-Pressure RF-ICP Discharge in Oxygen...

A kinetic study of the reaction between dichloromethane and atomic oxygen, produced by microwave discharge in oxygen diluted with helium, has been undertaken. The reaction products, detected by mass spectrometry, differ with the relative amounts of the reactants. In excess dichloromethane, the products are CO, HCl, Hg, and COClg with excess oxygen atoms, CI2, H2O, and ClOH are found in addition to the other products. Comprehensive investigations of the radiolysis of the liquid fluoromethanes CH F4 (0 < /I < 3) and gas-phase mixtures of CF4 and CCl4 have been carried out. The radiolysis of the liquid fluoromethanes was undertaken in an attempt to assess the effect that the structure of the molecules has... 

The rate of removal of ozone will then be kg[H][Oa], and since ka — din [0]/dt = 2 7(0][Oa][M]. Thus, the apparent third-order rate constant for O - - Oa + M would increase by a factor of two when a trace of moisture is added to dry Oa. A further problem arises from the presence of significant concentrations of Oa( Ag) when 0( P) atoms are produced by a discharge in oxygen. As Oa( Ag) is known to react with Oa, forming 0( P), the presence of singlet oxygen can thus lead to suppression of the decay of oxygen atoms ... 

Ozone (O3) is a colorless gas at ambient temperature and pressure and has a characteristic odor even at very low concentrations. It has a strong oxidizing ability that is hazardous to plants and animals, and is unstable especially at higher concentrations. Electric discharge in oxygen (or air) and irradiation of oxygen (air) with short-wavelength ultraviolet (UV) rays produce ozone. 

Ozone is produced by an electric discharge in oxygen gas its pungent odor is apparent near sparking electrical equipment and lightning strikes. 

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