The Decomposition equilibria of platinum di- and mono-chlorides by the simultaneous torque-knudsen technique

The decomposition equilibria of platinum dichloride have been found to consist of two decomposition steps, with chlorine molecules being the vapor species for both steps. An intermediate metastable PtCl solid is formed in the first step in addition to platinum metal and chlorine molecules. The platinum dichloride decomposes incongruently, the stepwise decomposition being PtCl₂ → PtCl → Pt. The PtCl₂ decomposition reactions consist of PtCl₂(s) = PtCl (metastables) + 1/2 Cl₂ (g) and PtCl₂(s) = Pt(s) + Cl₂ (g). The sum of the third lawΔH _{D, 298} K for the above two reactions is 214.637 ± 1.963 kJ/mole, in very good agreement with the second law ΔH_{D, 298 K} = 215.107 ± 13.062 kJ/mole. The second decomposition step is given by the reaction 2PtCl (metastables) = 2Pt(s) + Cl₂ (g) with a third law ΔH_{D, 298 K} = 127.356 ± 0.791 kJ/mole, in excellent agreement with the second law ΔH_{D, 298 K} = 127.509 ± 6.154 kJ/mole. The calculated heat of formation of PtCl₂ is -139 ± 2 kJ/mole and that of PtCl is -63 ± 1 kJ/mole. Formerly Graduate Assistant. Formerly Undergraduate Research Helper,     

Evaluation of defects in the seal region of food packages using the ultrasonic contrast descriptor, ΔBAI

A rapid, dependable method of on‐line package inspection will allow wider implementation of energy‐ and material‐efficient retortable pouches and trays, by reducing inspection costs. To evaluate high‐frequency ultrasonic imaging as a sensing method, the 17·3 MHz ultrasonic pulse‐echo Backscattered Amplitude Integral (BAI) method was used to visualize and evaluate major defects (channels and product inclusions, which compromise the seal integrity and must be reliably inspected) in the seal area of flexible food packages. The focus of this study was to evaluate the image contrast, denoted ΔBAI, for various packaging materials, defect types and sizes. Channel (6–100 µm in diameter) and inclusion defects (strands of mouse tail tendons, 20–150 µm) were created in the seal area of all‐plastic and foil‐containing packaging films. It has been shown that there is a direct relationship between the defect size and ΔBAI value, and that different defect types and packaging materials have a significant impact on the ΔBAI value. The utility of ΔBAI for detecting defects makes it a useful and reliable sensing method for package inspection. Copyright © 1999 John Wiley & Sons, Ltd.