Thermodynamic properties - specific heat

The ion-exchange heats in homoionic heulandite were measmed with a microcalorimeter [87R1]. In the case of K, NH4, Na, Mg, Ca, the selectivity of the zeolite was determined by the heat of hydratioa 

---

A more indirect but more versatile method consists in looking for signatures of the gap nodes in the d-density wave states. For low temperatures T A the nodal regions dominate thermodynamics and transport properties. Specific heat and thermal conductivity is equivalent to that of d-SC which have been discussed before. Susceptibility and frequency dependent electrical conductivity however are characteristic for the d-density wave states. Of course there is no vortex phase and the Doppler shift method cannot be applied. 

The glass transition point is typically not sharp and may take place over a range of more than 10 C. You should think of the glass transition more as a change in physical properties (specific heat capacity, volume) than a thermodynamic phase transition. 7 can be determined by two main methods Differential scanning calorimetry (see Chapter 2 for more... 

Thermal Properties and Enduranee. The heat capacity or specific heat, is a quantity of theoretical thermodynamic significance as well as of practical importance. It has been determined for Parylene N over the temperature range of 220 to 620 K (—53 to +347° C) (24,29). 

Enthalpy. Enthalpy is the thermodynamic property of a substance defined as the sum of its internal energy plus the quantity Pv//, where P = pressure of the substance, v = its specific volume, and J = the mechanical equivalent of heat. Enthalpy is also known as total heat and heat content. 

Available data on the thermodynamic and transport properties of carbon dioxide have been reviewed and tables compiled giving specific volume, enthalpy, and entropy values for carbon dioxide at temperatures from 255 K to 1088 K and at pressures from atmospheric to 27,600 kPa (4,000 psia). Diagrams of compressibiHty factor, specific heat at constant pressure, specific heat at constant volume, specific heat ratio, velocity of sound in carbon dioxide, viscosity, and thermal conductivity have also been prepared (5). 

A model of a reaction process is a set of data and equations that is believed to represent the performance of a specific vessel configuration (mixed, plug flow, laminar, dispersed, and so on). The equations include the stoichiometric relations, rate equations, heat and material balances, and auxihaiy relations such as those of mass transfer, pressure variation, contac ting efficiency, residence time distribution, and so on. The data describe physical and thermodynamic properties and, in the ultimate analysis, economic factors. 

The experiments result in an explicit measure of the change in the shock-wave compressibility which occurs at 2.5 GPa. For the small compressions involved (2% at 2.5 GPa), the shock-wave compression is adiabatic to a very close approximation. Thus, the isothermal compressibility Akj- can be computed from the thermodynamic relation between adiabatic and isothermal compressibilities. Furthermore, from the pressure and temperature of the transition, the coefficient dO/dP can be computed. The evaluation of both Akj-and dO/dP allow the change in thermal expansion and specific heat to be computed from Eq. (5.8) and (5.9), and a complete description of the properties of the transition is then obtained. 

Design formulas for plastics engineers , Natti S. Rao Hanser Gardner Pubis (1991) ISBN 1569900841. The formulas in this book are classified for specific areas, including rheology, thermodynamic properties, heat transfer, plastic and part type. 

Thermodynamic data (enthalpy of reaction, specific heat, thermal conductivity) for simple systems can frequently be found in date bases. Such data can also be determined by physical property estimation procedures and experimental methods. The latter is the only choice for complex multicomponent systems. 

The view that the clay surface perturbs water molecules at distances well in excess of 10 A has been largely based on measurements of thermodynamic properties of the adsorbed water as a function of the water content of the clay-water mixture. There is an extensive literature on this subject which has been summarized by Low (6.). The properties examined are, among others, the apparent specific heat capacity, the partial specific volume, and the apparent specific expansibility (6.). These measurements were made on samples prepared by mixing predetermined amounts of water and smectite to achieve the desired number of adsorbed water layers. The number of water layers adsorbed on the clay is derived from the amount of water added to the clay and the surface area of the clay. 

Table 8 displays the computed internal energy and specific heat at constant volume. The fact that these agree well with each other, and with experiment, despite the differences in local structure of liquids based on the two potentials emphasizes the insensitivity of thermodynamic properties (except pressure) to structural details. 

Salje E. (1988). Structural phase transitions and specific heat anomalies. In Physical Properties and Thermodynamic Behaviour of Minerals, E. K. H. Salje, ed. Reidel Pnblishing Company. 

---