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Determination of heat effects

Measurement of the heat effect associated with the degradation can be performed by differential thermal analysis (DTA). The degraded sample [Pg.7]

This method has been reviewed [16,17], and the theoretical aspects are outlined briefly below. Although DTA is more strictly applicable to stirred solutions, it finds most use in the case of solids. Consider a system of two cells in a heating bath at temperature T3 (Fig. 5). One cell contains [Pg.8]

The total heat evolved by the reaction is obtained by integrating between t = 0 and t = °°. [Pg.8]

The first term is equal to zero since AT, = AT0 = 0. Since AT as a function of t is recorded during the degradation, the area under the DTA curve is directly proportional to AH. If dH is a function of dWc the weight of the sample undergoing reaction, [Pg.9]

If the K term is much larger than the Cp term and T is substituted for t [Pg.9]


Linear differential equation of first order called the heat balance equation of a simple body, has found wide application in calorimetry and thermal analysis as mathematical models used to elaborate various methods for the determination of heat effects. It is important to define the conditions for correct use of this equation, indicating all simplifications and limitations. They can easily be recognized from the assumption made to transform the Fourier-Kirchhoff equation into the heat balance equation of a simple body. [Pg.20]

Classification of calorimeters Methods of determination of heat effects... [Pg.85]

Obviously, the experimental description of the device should also contain information such as 1) the purpose of the instmment (combustion, heat of mixing, heat capacity, sublimation, etc.) 2) the principles and design of the calorimeter proper, including the ranges of temperature and pressure in which measurements can be performed 3) the measured quantity and measuring device 4) the static and dynamic properties of the calorimeter the calibration mode and the methods of measurement and determination of heat effects 5) the operational characteristics of the calorimetric device, the sensitivity noise level, the method of calibration, the accuracy, etc. 6) a description of the experimental procedure used in the calibration and the actual measurements. [Pg.97]

Improved conditions in calorimetric experiments lead to the creation of more precise mathematical calorimeter models and methods used for the determination of heat effects. [Pg.131]

EXPERIMENTAL DETERMINATION OF HEAT EFFECTS THAT ACCOMPANY SORPTION EQUILIBRIUM PROCESSES... [Pg.72]

Overview One of the most important considerations involved in designing gas-absorption towers is to determine whether or not temperatures will vaiy along the length of the tower because of heat effects, since the sohibility of the solute gas normally depends strongly upon the temperature. When heat effects can be neglected, computation of the tower dimensions and required flows is relatively straight-... [Pg.1358]

ISO 4611, Plastics - Determination of the effects of exposure to damp heat, water spray and salt mist, 1987. [Pg.80]

Determination of the Effect of Water on Poljnnerization. To a solution of 4.76 mmole of HFB and 4.76 mmole of Bis-A in 20 ml of the appropriate solvent of known water content was added 20.6 mmole of K2CO3 and 1.32 mmole of 18-crown-6 ether. The crown ether, when necessary was dried by complexation with acetonitrile. Water content of solvent and catalyst was determined in all runs by Karl Fischer titration. Known microliter quantites of water in increments of lOyl were then added to the reaction mixture. The magnetically stirred, heterogeneous mixture was heated in an oil bath and maintained under N2. Upon cooling to room temperature, the reaction mixture was slowly poured into ca. 300 ml of a nonsolvent vigorously stirred in a blender. The filtered solids were washed three times with 300-ml portions of distilled water. [Pg.140]

Dunkle s Syllabus (1957-1958) Shock Tube Studies in Detonation (pp 123-25) Determination of Pressure Effect (144-45) Geometrical and Mechanical Influences (145-48) Statistical Effects of Sensitivity Discussion on Impact Sensitivity Evaluation (148-49) Pressure in the Detonation Head (175) Temperature of Detonation (176) Charge Density, Porosity, and Granulation (Factors Affecting the Detonation Process) (212-16) Heats of Explosion and Detonation (243-46) Pressures of Detonation (262-63) A brief description of Trauzl Block Test, Sand Test, Plate Dent Test, Fragmentation Test, Hess Test (Lead Block Crushing Test), Kast Test (Copper Cylinder Compression Test), Quinan. Test and Hop-kinson Pressure Bar Test (264-67) Detonation Calorimeters (277-78) Measurements... [Pg.315]

Table 15.1 A Two-Factorial Design for Experimental Determination of the Effects of Pressure, Heating Rate, and Temperature... Table 15.1 A Two-Factorial Design for Experimental Determination of the Effects of Pressure, Heating Rate, and Temperature...
The standard Gibbs energy change of reaction, AG°, is used in the calculation of equilibrium compositions the standard heat of reaction, AH°, is used in the calculation of heat effects of chemical reaction and the standard heat capacity change of reaction is used for extrapolating AH0 and AG0 with T. Numerical values for AH° and AG0 are computed from tabulated formation data (15,16), and AC°p is determined from empirical expressions for the T dependence of the C° (8). [Pg.501]

Optimization of coal sampling is a function of the many variable constituents of coal. The effect of fineness on the combustion of pulverized coal is dramatic, and the special problems associated with collection of an unbiased sample of pulverized coal need to be addressed (ASTM D-197). Operating samples are often collected from the coal streams to power plants on a regular basis not only for determination of heat balance but also to document compliance with air pollution emission regulations. [Pg.23]

A general discussion of calorimetric measurements is presented in the section Principles of Calorimetry, which should be reviewed in connection with this experiment. We shall not consider here the concentration dependence of these enthalpy changes. Such concentration dependence is generally a small effect, since the heats of dilution involved are usually much smaller than the heats of chemical reaction (indeed they are zero for perfect solutions). Since we are dealing here with solutions of moderate concentration, particularly in the case of the NaOH solution, it may be useful to make parallel determinations of heats of dilution of the solutions concerned by a procedure similar to that described here if time permits. [Pg.167]

DSC has been used to determine the heat effects associated with propene adsorption [84] on Mo/Si Ti catalysts with different K Mo molar ratios. The heats associated with reversible (-3.193 x 10 mjm pie) and irreversible (-0.126 X10 mj msampie) adsorption of propene were found to decrease with the addition of potassium. [Pg.417]

Convection is the mode of energy transfer between a solid surface and the adjacent liquid or gas that is in motion, and it involves the combined effects of conduction and fluid motion. The faster the fluid motion, the greater the convection heal transfer. In the absence of any bulk fluid motion, heat transfer between a solid surface and the adjacent fluid is by pure conduction. The presence of bulk motion of the fluid enhances the heat transfer betxveen the solid surface and the fluid, but it also complicates the determination of heat transferrates. [Pg.45]

Aliquid solution contains 1 mol of CaCl2 and 25 mol of water. Using datafromPb. 12.37, determine the heat effect when an additional 1 mol of CaCl2 is dissolved isothennally in this solution. [Pg.447]

At moderate temperatures and pressures the second term on the right-hand side of equation (21.13) may be neglected the value of Cp should thus increase in a linear manner with the pressure. The rate of increase should be less the higher the temperature. With increasing pressure the effect of the second term will become appreciable, especially at low temperatures, and at sufficiently high pressures Cp should reach a maximum and then decrease. These qualitative expectations are in agreement with the results obtained by the application of P-F-T data to equation (21.12), and also with the limited experimental determinations of heat capacities at high pressures. ... [Pg.169]


See other pages where Determination of heat effects is mentioned: [Pg.7]    [Pg.91]    [Pg.97]    [Pg.7]    [Pg.91]    [Pg.97]    [Pg.501]    [Pg.372]    [Pg.25]    [Pg.174]    [Pg.106]    [Pg.174]    [Pg.201]    [Pg.317]    [Pg.23]    [Pg.103]    [Pg.80]    [Pg.291]    [Pg.185]    [Pg.395]    [Pg.351]    [Pg.20]    [Pg.395]    [Pg.219]    [Pg.290]    [Pg.115]    [Pg.151]    [Pg.130]    [Pg.387]   


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Effect of heating

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