The Effect of Moisture and Paraffin Surface on the Rate of Reaction of Nitric Oxide and Oxygen

Abstract

In a previous investigation,2 the effect of increased glass surface on the velocity of the reaction between nitric oxide and oxygen was studied. It appeared that this rapid reaction is not greatly affected by surface; that it takes place chiefly in the gas phase. When we consider that the rate of the reaction which we measure is the sum of the rates by different paths, altering the kind or amount of surface may be supplying or removing a catalyst. Accordingly, the net speed may be altered by introducing or eliminating paths through which the reaction may proceed. As possibilities of catalysts in the present case we may consider nitrogen tetroxide or moisture. Cohn and Jung3 have recently shown in their study of the photochemical union of chlorine and hydrogen that with a pressure of water vapor under 10-7 mm. of mercury, no combination occurs; at a pressure of 10-6 mm., 88% is converted and at 10-3 mm. maximum catalysis results. This means that in case a film of moisture on a surface acts as a catalyst, only a very low moisture content, perhaps a monomolecular layer, is necessary to produce the maximum effect. More recently Norrish4 has calculated from the description of the apparatus used in the experiments of Cohn and Jung that at a pressure of 10 ~3 mm. of mercury the monomolecular layer on the surface of the reaction vessel was just complete. Bodenstein and Dux5 also found that evacuation to 10 ~3 mm.

The Rate and Mechanism of the Air Oxidation of Parts-per-Million Concentrations of Nitric Oxide in the Presence of Water Vapor

“…In addition, the nature of the reactor surface affected the rate. This observation was made in the studies of Hasche (1926) and Smith (1943).…”

“…Some investigators have reported that water vapor has no effect on the oxidation Hall, 1966, 1967; Treacy and Daniels, 1955). Others have found that water vapor may increase or decrease the rate of oxidation (Burdick, 1922;Hasche, 1926; Smith, 1943;Stoddart, 1939). Earlier studies in this laboratory showed that nitrogen dioxide was consumed in the gas phase by water vapor.…”

“…These he attributed to the adsorption of nitric oxide on the reactor surface. Hasche (1926) reported that water catalyzed the oxidation of nitric oxide. At pressures of 91 mm Hg of nitric oxide and 115.5 mm Hg of oxygen, small amounts of water increased the rate of reaction up to 50%.…”

“…The oxidation of nitric oxide apparently was not greatly affected by the presence of water vapor. Only Hasche (1926) reported that water vapor increased the rate of oxidation. His work was done with high concentrations of both nitric oxide and oxygen.…”

Absorption of Nitrogen Dioxide by Aqueous Solutions

“…workers, are apparently good only for dry gases, since with wet gases, with paraffin-coated vessels, or in contact with charcoal, the rate constants are quite different (5, 6,14). It seems unlikely that Bodenstein's rate data are exactly applicable under the conditions obtaining in industrial absorption equipment, although Taylor,Chilton,and Handforth (92) found them of value in this connection.…”