Part I. Iodometric Determination of Copper. Section I. The Use of Thiocyanate. Section II. The Use of Sulfate-Hydrogen Sulfate Buffers. Part II. The Use of Iodine Monochloride End-Point for the Titration of Antimony Using Ceric Sulfate, Potassium Permanganate and Potassium Iodate Solutions. Part III. The Use of Iodine Monochloride as an Indicator in the Titration of Thiocyanate with Permanganate, Iodate and Ceric Sulfate. Part IV. The Distribution of Thallium Between Isopropyl Ether and Hydrochloric Acid

Citation

Hammock, Edward Woodrow (1947) Part I. Iodometric Determination of Copper. Section I. The Use of Thiocyanate. Section II. The Use of Sulfate-Hydrogen Sulfate Buffers. Part II. The Use of Iodine Monochloride End-Point for the Titration of Antimony Using Ceric Sulfate, Potassium Permanganate and Potassium Iodate Solutions. Part III. The Use of Iodine Monochloride as an Indicator in the Titration of Thiocyanate with Permanganate, Iodate and Ceric Sulfate. Part IV. The Distribution of Thallium Between Isopropyl Ether and Hydrochloric Acid. Master's thesis, California Institute of Technology. doi:10.7907/4ykb-rz18. https://resolver.caltech.edu/CaltechTHESIS:05052025-230344625

Abstract

I. This part of the thesis reports a study of some of the limitations encountered in the iodometric determination of copper. The sulfate-hydrogen sulfate buffer was introduced for this determination. The permissible pH range for this buffer was found to be from about O.5 to 3. It was found that the "oxygen error" was not noticeable even at the lower limits of this range and the end-points were stable enough for a normal titration. Chlorides and nitrates do not cause serious errors. The procedure using the sulfate buffers and thiocyanate was tested against pure copper and copper alloys which contain interfering constituents. The results show that the percentage difference from the theoretical is less than one part per thousand.

The effect of adding thiocyanate at various points during the titration, the amount required, and the necessity of using pure thiocyanate were studied and reported. A study of the difference of the iodide and thiocyanate end-points was made. It was observed that a small excess of thiosulfate could be back titrated. Several wetting agents as well as shellac were tried in an attempt to protect the cuprous iodide during this back titration.

II. A study has been made of the titration of antimony with permanganate, eerie sulfate, and iodate solutions, using the iodine monochloride as the indicator. The oxidizing solutions were standardized against Bureau of Standards arsenious oxide by two methods which agreed within one part per thousand. In the analysis of an antimony ore, the amount of antimony found was about three parts per thousand too high of that present.

III. A study of the titration of thiocyanate has been made in which permanganate, iodate and eerie sulfate were used as the oxidizing agents, and iodine monochloride used as the indicator. Results show that iodate titration gives results within one part per thousand, the permanganate titration within three parts per thousand, and eerie sulfate titration was not satisfactory. Potassium thiocyanate can be used as a primary standard.

IV. This report is a progress report on the study of the distribution of thallium between isopropyl ether and hydrochloric acid solution. The method for purifying the ether and the method of the analyzing the ether and water layers is given. There is not sufficient data to draw any definite conclusions as to the distribution curve nor the extracted species.

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