Date of Award

1984

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry & Biochemistry

Program/Concentration

Chemistry

Committee Director

Billy T. Upchurch

Call Number for Print

Special Collections LD4331.C45 A44

Abstract

Isotopic exchange reactions with the surface of amorphous silica and crystalline quartz were studied mass spectrometrically. A mixture of approximately 2%18o2 in neon was used as the test gas, and was passed over the surface of the oxides. Measurements were taken as a function of temperature and residence time, for kinetic studies.

These studies clearly show a second order rate law for the surfaces examined. The rate constant on amorphous silica was 2.2xl02L/mol/sec. The energy of activation was 35.3 kcal/mol and the frequency factor was l.35xl09L/mol/sec. On the crystalline quartz the rate constant was 2.0xl02L/mol/sec. The energy of activation was 65.2 kcal/mol and the frequency factor was 4.52xl02L/mol/sec.

The postulated mechanism for a bimolecular reaction would occur at temperatures above that required for dehydroxylation. This allows chemisorption of a molecule of 18o2 to form a bridged six-membered ring upon which a subsequent collision of a second 18o2 molecule results in an oxygen isotope exchange.

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DOI

10.25777/ksew-vn20

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