Date of Award

Spring 1958

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Kittsley, Scott L.

Second Advisor

Bournique, R. A.

Third Advisor

Hermann, Karl L.

Abstract

Although the amount of research in various fields has mushroomed in recent years, there still are large areas where little or no work has been done. The field of reaction kinetics, in particular, has not been extended as far as could be hoped for. General notions are prevalent on the probable paths of various reactions, but with little exact data to substantiate them. The specific reaction with which this paper is concerned is a familiar one in many fields. This is the reaction between ammonium bichromate and a colloid such as albumen, casein, or gum arabic. Ordinarily this reaction proceeds at a relatively slow rate which may vary depending upon the concentrations of these materials, their purity, the temperature and, in the case of dried films, the relative humidity. Since the practical importance of this reaction is confined, nearly entirely, to its progress in a semi-solid film state, the research in this paper will deal exclusively with this physical form of the reactants. The field of photo-lithography these "sensitized" colloidal films have been particularly important. Their usefulness, however, has been severely limited by the slow reaction between ammonium bichromate and colloid in the absence of light. The ammonium bichromate-colloid film is sensitive to actinic light and this is where its practical importance lies. Any measurable reaction in the absence of light is undesirable but nevertheless occurs with a regularity that has been observed for many years. A more exact knowledge of the path of this "dark reaction" would be of value in efforts made to retard and/or control its rate. Thus, the problem is similar to the control of dark reaction rates on photographic film in the early days of photography. The tendency of a photographic film to "expose" in the absence of light at first put serious limitations on the practical use of such a film. Needless to say, the problem was solved to the extent that today we can leave an inexposed photographic film in the camera for months without any serious danger of deterioration. An attempt has been made, in this paper, to study the rate of the dark reaction under a wide variety of temperature and humidity conditions. From the data accumulated it has been possible to derive a mathematical expression which seems to hold well under normal conditions. it is to be hoped that this study might lend itself to a clearer understanding and definition of the dark reaction.

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