The photolysis of calcium, barium, strontium and lithium azides and the co-irradiated decomposition of calcium azide

• Main Author: O'Connor, Cyril Thomas
• Other Authors: Prout, E G
• Format: Doctoral Thesis
• Language: English
• Published: University of Cape Town 2016
• Subjects: Chemistry
• Online Access: http://hdl.handle.net/11427/18116

Bibliography: p. 377-384. === The effect of very high intensity ultraviolet radiation on powdered calcium, barium, strontium and lithium azides in the temperature range -80,0° - 35,0°C has been studied. Powdered and pelleted calcium azide was also irradiated with ultraviolet radiation in the temperature range 35,0° - 90,0°C and powdered lithium azide in the temperature range 24,0° - 170,0°C. All these decompositions were purely photolytic. Powdered and pelleted calcium azide was also subjected to ultraviolet radiation in the temperature range 110,0° - 140,0°C. This latter decomposition was termed co-irradiation due to the fact that both thermal and photolytic mechanisms were operative in this temperature range. Except at low temperatures, the extent of the decomposition was almost the same as that of a simple thermal decomposition. Kinetic analyses, determination of activation energies, studies of the dependence of reaction rates on light intensity, the effect of introducing water vapour to the sample at various stages of decomposition and the observance of the colour of the sample at various stages of reaction have been carried out. Analogous results were obtained for all four azides at low temperatures and the results obtained for calcium and lithium azides at ambient and higher temperatures were analogous to those obtained for barium and strontium azides under similar conditions by previous workers. During photolysis the activation energy undenvent transitions, in all four azides, in the region of 0°C and in the region of 60°C. Co-irradiation studies of calcium azide commenced at temperatures greater than 100°C. Similar studies were not carried out on lithium azide since even at temperatures in the region of 180°C the rate of photolytic decomposition was very much greater than that of a purely thermal decomposition at the same temperature.