1,2,4-Triazole as a reference material for combustion calorimetry of N-containing compounds

Abstract

A micro-bomb combustion calorimeter recently designed for samples of mass ≈80 mg has been improved and tested with m-methoxybenzoic acid in order to verify the chemistry of the combustion process and the accuracy of the energy corrections involved in the analysis of results. From measurements in this calorimeter, the standard massic energy of combustion of 1,2,4-triazole was determined to be Δcuo = -(19200.3 ± 3.4) J·g-1. Some new measurements with our macro combustion calorimeter confirm an earlier result from this laboratory of -(19203.1 ± 1.2) J·g-1. Determination of the purity by d.s.c. of 1,2,4-triazole purified some 10 years ago reveals that samples of this compound remained unchanged and suggest that 1,2,4-triazole be used as a possible reference material for organic compounds with a high content of nitrogen. From the experimental results with the micro-bomb combustion calorimeter, the actual and earlier results from macro-bomb combustion calorimetry, and those obtained in other laboratories, the standard massic energy of combustion of 1,2,4-triazole was deduced to be Δcuo = -(19202.5 ± 1.7) J·g-1. © 2000 Academic Press.