Calorimetric Determination of Purity: Design and Operation of a Small Adiabatic Calorimeter

Abstract

An adiabatic calorimeter has been developed for determination of the purity of the reference compounds required for spectroscopic investigations. Two interchangeable calorimeters with volumes of 0.5 and 5 ml. are used. A complete determination, including calculations, usually requires less than 4 hours. Although the purity determination is based on the measurement of the melting point depression, this method, unlike conventional melting point methods, does not require a previous determination of the heat of fusion and the melting point of the pure compound. Instead, the method determines these quantities as part of the analysis. The calorimeter is used to measure the equilibrium temperature of the sample as a function of heat input as it passes from the solid state to the liquid state.

The Thermal Decomposition of Nitrate Esters. III. n-Propyl Nitrate1

“…The effect of various additives on the rate of reaction and on the product distribution is shown in Table II. Discussion The above reaction products are analogous to those found for the ethyl nitrate decomposition and fit in well with the mechanism proposed.2 The repropyl nitrate case differs from the ethyl nitrate case in that (a) the nitro compound is a much more important product and (b) the kinetics obey a simple first-order law and are virtually unaffected by the addition of substantial amounts of nitric (1) Full experimental details of this work including infrared spectra can be found in the reference, J. B.…”

Structural and Thermal Properties of Unpurified and Purified 12-Hydroxystearic Acid Solutions

“…On heating, a sharp and large endothermic peak for p-12-HSA powder was observed at 80.9°C, which is close to the value of the melting temperature for 12-HSA powder with 99% purity [12]. We attempted to calculate the purity of p-12-HSA sample from the endothermic peak by using the fractional melting method [13,14], to estimate sample purity as 96 %. In a cooling process, a very sharp exothermic peak observed at 74.2°C is attributed to the crystallization of 12-HSA.…”

Thermodynamic Consideration on a Series of Compounds (CH3)nCCl4-n: Correlation between Molecular Sphericity, Configurational Order/Disorder, and Molecular Packing in Plastically Crystalline and Liquid Phases

“…The estimated temperatures for tert -butyl chloride and 2,2-dichloropropane were plotted as a function of the reciprocal of the fraction melted, f , in Figure a,b, respectively. These points were fitted in terms of a straight line and analyzed by the van't Hoff equation . The fusion temperature and the mole-fraction purity were determined to be 248.6 ± 0.1 K and 0.9993 for tert -butyl chloride, and 239.6 ± 0.1 K and 0.9995 for 2,2-dichloropropane, respectively.…”