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I. The Rate and Mechanism of the Vapor-Phase Reaction Between Water and Parts-Per Million Concentrations of Nitrogen Dioxide. II. The Rate and Mechanism of the Air Oxidation of Parts Per-Million Concentrations of Nitric Oxide in the Presence of Water Vapor

Citation

England, Christopher (1970) I. The Rate and Mechanism of the Vapor-Phase Reaction Between Water and Parts-Per Million Concentrations of Nitrogen Dioxide. II. The Rate and Mechanism of the Air Oxidation of Parts Per-Million Concentrations of Nitric Oxide in the Presence of Water Vapor. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/y6gn-rt03. https://resolver.caltech.edu/CaltechTHESIS:08042015-081657144

Abstract

Part I

A study of the thermal reaction of water vapor and parts-per-million concentrations of nitrogen dioxide was carried out at ambient temperature and at atmospheric pressure. Nitric oxide and nitric acid vapor were the principal products. The initial rate of disappearance of nitrogen dioxide was first order with respect to water vapor and second order with respect to nitrogen dioxide. An initial third-order rate constant of 5.5 (± 0.29) x 104 liter2 mole-2 sec-1 was found at 25˚C. The rate of reaction decreased with increasing temperature. In the temperature range of 25˚C to 50˚C, an activation energy of -978 (± 20) calories was found.

The reaction did not go to completion. From measurements as the reaction approached equilibrium, the free energy of nitric acid vapor was calculated. This value was -18.58 (± 0.04) kilocalories at 25˚C.

The initial rate of reaction was unaffected by the presence of oxygen and was retarded by the presence of nitric oxide. There were no appreciable effects due to the surface of the reactor. Nitric oxide and nitrogen dioxide were monitored by gas chromatography during the reaction.

Part II

The air oxidation of nitric oxide, and the oxidation of nitric oxide in the presence of water vapor, were studied in a glass reactor at ambient temperatures and at atmospheric pressure. The concentration of nitric oxide was less than 100 parts-per-million. The concentration of nitrogen dioxide was monitored by gas chromatography during the reaction.

For the dry oxidation, the third-order rate constant was 1.46 (± 0.03) x 104 liter2 mole-2 sec-1 at 25˚C. The activation energy, obtained from measurements between 25˚C and 50˚C, was -1.197 (±0.02) kilocalories.

The presence of water vapor during the oxidation caused the formation of nitrous acid vapor when nitric oxide, nitrogen dioxide and water vapor combined. By measuring the difference between the concentrations of nitrogen dioxide during the wet and dry oxidations, the rate of formation of nitrous acid vapor was found. The third-order rate constant for the formation of nitrous acid vapor was equal to 1.5 (± 0.5) x 105 liter2 mole-2 sec-1 at 40˚C. The reaction rate did not change measurably when the temperature was increased to 50˚C. The formation of nitric acid vapor was prevented by keeping the concentration of nitrogen dioxide low.

Surface effects were appreciable for the wet tests. Below 35˚C, the rate of appearance of nitrogen dioxide increased with increasing surface. Above 40˚C, the effect of surface was small.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemical Engineering
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Corcoran, William Harrison
Thesis Committee:
  • Unknown, Unknown
Defense Date:4 May 1970
Funders:
Funding AgencyGrant Number
U. S. Public Health ServiceUNSPECIFIED
National Center for Air Pollution ControlUNSPECIFIED
NSFUNSPECIFIED
CaltechUNSPECIFIED
Record Number:CaltechTHESIS:08042015-081657144
Persistent URL:https://resolver.caltech.edu/CaltechTHESIS:08042015-081657144
DOI:10.7907/y6gn-rt03
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9075
Collection:CaltechTHESIS
Deposited By: Leslie Granillo
Deposited On:04 Aug 2015 20:47
Last Modified:25 Jun 2021 21:34

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