I. Kinetics of the Reactions of Silver, Lead and Thallium with Thioacetamide. II. The Distribution of Barium, Titanium, Manganese, Iron, Nickel and Cobalt in Stony Meteorites

Author: Moore, Carleton Bryant

Year: 1960

Degree: Dissertation (Ph.D.)

Advisors: Swift, Ernest H.; Brown, Harrison

Committee Member: Unknown, Unknown

Option: Chemistry

DOI: 10.7907/W8C0-E784

Abstract

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The precipitation of silver from acid solutions by thioacetamide at 60°C was investigated. Below pH 2 the reaction takes place predominantly by the hydrolysis of thioacetamide to form hydrogen sulfide. Above pH 2 a direct reaction between the silver and thioacetamide has a significant effect. The direct reaction rate equation was found to be [...]. At 60°C in a malonic acid - 0.1 VF sodium hydrogen malonate buffer k" is 8.6 x 10(-7) mole 7/2 liter 7/2 minute(-1).

The presence of chloride ion inhibits the rate of direct reaction between lead and thioacetamide. The reaction is first order with respect to PbCl+ and about 50% slower than with Pb++ at 90°.

Thallous sulfide is precipitated by thioacetamide by both hydrolysis and direct reactions. The direct reaction is second order with respect to thallium, first order with respect to thioacetamide and probably inverse half order with respect to hydrogen ion.

The concentrations of barium, manganese and titanium have been determined spectrographically in 94 stony meteorites. There appear to be four barium concentration groups with median barium concentrations of 5, 10, 25 and 150 ppm. For the falls the average concentrations of manganese and titanium are 0.260 ± 0.028% and 0.064 ± 0.008%. For the finds the manganese content is 0.235 ± 0.023% and the titanium content is 0.059 ± 0.007%. The presence of grouping in chondrites has been confirmed by X-ray fluorescence spectroscopic analysis.

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