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Date of Award

1968

Document Type

Dissertation - Pacific Access Restricted

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Chemistry

First Advisor

Herschel Frye

First Committee Member

Richard P. Dodge

Second Committee Member

Floyd Helton

Third Committee Member

Neil Lark

Fourth Committee Member

Calvin Potts

Abstract

The purpose of the present work was to (1) determine the feasibility of performing radiometric titrations using low activity radioisotopes and inexpensive equipment; (2) develop a workable procedure for performing ·radiometric titrations in the classroom; and (3) assemble the basic radioactive concepts needed so the content could be used in a chemistry course of study.

The limited work done previously with radiometric titrations has used solutions of high specific activity and relatively large volumes of solution. The use of high activity radioisotopes creates problems of radioisotope procurement, shielding, handling and disposal. The use of high activity radioisotopes required special training and licensing. This imposed a severe limitation on the number of persons that could perform radiometric titrations. Thus to make this technique available to a large number of classroom teachers and other similarly qualified persons, it was imperative that a procedure be devised that would allow radiometric titrations to be performed using low activity, license free radioisotopes.

The low activity of the license free radioisotopes necessitated the delineation of the physical conditions that could best utilize the limited activity of the solution. The amount of radioisotope used was determined as an amount low enough to simplify or eliminate the problems of procurement, shielding, handling and disposal but yet have a sufficient count rate to enable precise and accurate results.

A physical setup was devised that met the desired criteria. Using this setup, the feasibility of radiometric titrations was determined for precipitation reactions using, as the indicator, one or more of the following radioisotopes: Ca-45; I-125; I-131; Ag-110; Cl-36; W-185; Tl-204; and S-35.

The isotopes selected allowed delineation of systems having wide variation of emission type and energies. Thus in addition to the systems deliniated, this allows the prediction of the usefulness of isotopes for other systems than those investigated.

The systems using Ca-45, S-35, and Tl-204 were found capable of giving very good results.

A field study was· conducted in which a total of sixty-two students performed a radiometric titration. Their average results agreed almost exactly with the accepted value. Their average deviations were of the same order of magnitude as the accuracy reported in many studies using radioisotopes of high activity.

The effects of complexation and pli dependence was also studied for some of the systems. The affect on the titration curve shape agrees well with the theoretical predictions.

Therefore, in addition to the deliniation of new systems for radiometric titrations, this study provided a method of teaching radioactive concepts in a manner that allows safe student participation. Student participation not only allows the teaching of radioactive concepts, the techniques of radioactive solution handling and disposals, and an analytical method, but also allows ready observation of the factors affecting solubility.

Pages

136

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