Thermometric method

Experiment.—Determitie the Transition Point of Glauber s Salt by the Thermometrie Method. 

A moderately large quantity (30 to 50 grms.) of recrystallized sodium sulphate decahydrate is placed in a thin glass tube, so 

The temperature readings for the mixture in the tube are plotted against the time, and in this way two curves will be obtained, one for rising and the other for falling temperature, each showing an approximately perpendicular portion. Owing to suspended transformation, these two perpendicular portions may not coincide. 

Repeat the experiment, but allow the temperature of the bath to rise more slowly between 32° and 33 . Again read the temperature on the thermometer in the tube every minute, and plot the results as before. 

Similar determinations may also be carried out with the salts given in Table I. of the Appendix. 

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J)Other analytical methods which include, among many, a thermometric method (104), a high frequency titration (105), and a colored indicator method (106). 

A thermometric method of evaluating the fuming acid consists in adding excess of standard 80 per cent, sulphuric acid and titrating back with the fuming acid the temperature of the solution rises with each addition of the fuming acid until the water content of the standard is exhausted.3... 

For solutions containing sulphuric acid only, direct titration with standard alkali, and measurement of the specific gravity, are possible as methods of estimation, provided that the process in either case is, if necessary, preceded by suitable dilution (see p. 165). Thermometric methods have also been suggested, depending on the rise in temperature when the acid is mixed with water, or when titrated with barium chloride solution.4 The water content of the concentrated acid may be determined by similar titration with oleum which has been standardised thermometrically by 80 per cent, sulphuric acid (see p. 147 ).5... 

This thermometric method, which consists of measuring the temperature of a reactive medium in an adiabatic polymerization process T(t), is quite close to the calorimetric method. If we assume that the product of specific heat and density, Cpp, does not depend on temperature and the degree of conversion (this assumption is quite realistic), then it is possible to relate changes in temperature dT to heat output dq ... 

The kinetics of polyurethane curing in adiabatic conditions was studied by the thermometric method (see Section 2.2) for a composition based on macro(diisocyanate) and diamine.48 It was proved that in this case, the second-order kinetic equation was inapplicable for the rangep > 0.7. By analyzing the time dependencies of temperature of the reactive medium, it was established that the... 

Conventional thermometric titrimetry was used to determine base and acid content in light and heavy petroleum derivatives, including lubricating oils (Quilty, 1967), crude oils (Borrull et al., 1986a) and petroleum distillates (Borrull et al., 1986b Greenhow andNadjafi, 1979). Studies show that the acids in the oils not determined by the thermometric method are weaker than pKa(H20) = 10. 

Mateo MD, Forteza R, Cerda V, et al. 1988. Comparative study of a kinetic - thermometric method and the atomic-absorption cold-vapour technique for determination of mercury traces and ultra-traces. Thermochimica Acta 128 21-30. 

In the recent past, multianalyte determination has found increased applications, i.e. specific and multiple reactions favor a system that allows the specific determination of each reaction, using the same principal measurement methods, detectors and conditions. In keeping with this idea, a flow injection thermometric method based on an enzyme reaction and an integrated sensor device was proposed for the determination of multiple analytes. In principle the technique relies on the specificity of enzyme catalysis and the universality of... 

More recently, it was demonstrated that the thermistor approach could be used to monitor specific interactions of fluoride ions with silica-packed columns in the flow injection mode. A thermometric method for detection of fluoride [56] was developed that relies on the specific interaction of fluoride with hydroxyapatite. The detection principle is based on the measurement of the enthalpy change upon adsorption of fluoride onto ceramic hydroxyapatite, by temperature monitoring with a thermistor-based flow injection calorimeter. The detection limit for fluoride was 0.1 ppm, which is in the same range as that of a commercial ion-selective electrode. The method could be applied to fluoride in aqueous solution as well as in cosmetic preparations. The system yielded highly reproducible results over at least 6 months, without the need of replacing or regenerating the ceramic hydroxyapatite column. The ease of operation of thermal sensing and the ability to couple the system to flow injection analysis provided a versatile, low-cost, and rapid detection method for fluoride. 

Because this chapter is intended to examine only potentiometric and thermometric methods of functional group analysis, the irreversible methods of analysis of acidic functional groups [reaction of acidic H with CH2N2, LiAlH4, or (BH3)2] are not discussed. The most likely potentiometric proce-... 

Equipment for thermal analysis is used extensively for the preformulation study. As in the solid-state investigation, interest is focused not only on the chemical change but also on the physical change, which can be illustrated appropriately by thermometric methods. 

IV. Thermometric Method.—If a crystalline solid is heated, its temperature will gradually rise until the melting-point is reached, and the temperature will then remain constant until all the solid has passed into liquid. Similarly, if a substance which can undergo transformation is heated, the temperature will rise until the transition point is reached, and will then remain constant until complete transformation has taken place. 

Thermometric methods (not to be confused with thermometric titrations) in which temperature-time curves are obtained at various intervals. Heat evolution or absorption occurs continuously and preferably at a constant rate. The amount of heat supplied per unit time is not measured directly but may be calculated as a fraction of the total heat of melting of the substance. 

Note. — Determinations made by the so-called thermometric method, i.e., by observing the temperature of the disappearance of the separated, finely divided solid from solutions of known concentration. 

Thermometric methods of analysis have wide analytical applications. They can be used not only for the identification of chemical compounds, but also for the quantitative analysis of mixtures of compounds and for characterizing many types of engineering materials such as... 

H Neubert, H Harig and K Schulte, Monitoring of fatigue induced damage processes in CFRP by means of thermometric methods , ICCM-V 1/ ECCM-2, Imperial College, London, Elsevier Apphed Science, 1987. 

The identification of polymeric grains as microreactors, in which the polymerization process is localized from the moment of grain formation and until the moment of their contact and propagation into a microheterogeneous polymeric body, has been carried out by sol-gel analysis [122] and thermometrical methods [1231 in studies of oligoesteracrylates polymerization kinetics. 

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