Calorimeter Nernst

Page 14, line 2 The method of Nernst, Koref, and Lindemann, by the use of the copper-calorimeter, determines the mean specific heat over a range of temperature. The mode of procedure is the same as in ordinary calorimetry, except that a hollow block of copper, the temperature of which is determined by means of inserted thermoelements, is used instead of a calorimetric liquid, and the method therefore made applicable to very low temperatures. 

In a method used by Thomsen the given liquid, e.g. a solution, was used as the calorimeter liquid and heat given to it by the combustion of hydrogen or by a chemical reaction (e.g. the dilution of sulphuric acid, in a vessel immersed in the liquid. A known mass of heated solid can also be immersed in the liquid in a calorimeter. Schiff enclosed the liquid in a platinum vessel of cross-shaped section, containing a thermometer. This was heated to a given temperature and then put into the calorimeter, and stirred round in the water. The liquid was in layers only 1 cm. thick and a rapid equalisation of temperature was thus ensured. Schlesinger heated the liquid electrically and deduced the rise in temperature from the measured increase in volume and the coefficient of expansion. Specific heats of liquids at low temperatures ca,n be determined by a modification of the Nernst calorimeter, in which the liquid in a small steel vessel contained in a... 

Nernst, Koref, and Lindematm (1910) described an aneroid drop calorimeter for the measurement of specific heat capacities. Figure 7.14 shows the design of this instrument. The entire system is located in isothermal surroundings such as melting ice. Of particular interest is the measurement of the temperature change of the calorimeter substance by means of 10 iron-constantan thermocouples mounted between the calorimeter substance and the isothermal Ud. 

Figure 7.14 Drop calorimeter according to Nernst, Koref, and Lindemann (from Nernst, Koref, and Lindemann, 1910).

At the suggestion of Nemst, Eucken (1909) developed a calorimeter for the measurement of specific heat capacities at low temperatures. Nemst (1910, 1911) used a similar calorimeter without major modifications for the measurement of a large number of specific heat capacities to a temperature of 23 K. To test his own heat theorem ( third law of thermodynamics), Nernst strove to measure the specific heat capacity as much point by point as possible as a function of temperature. An average specific heat capacity over a relatively large temperature range was worthless for this purpose. 

Precise measurements of heat capacity may also be made in a calorimeter with a shield at constant temperature (the Nernst calorimeter). The heat lost or gained during each measurement is determined accurately. 

Adiabatic calorimeters have only become possible with advanced designs for electrical temperature measurement and the availability of regulated electrical heating. The first adiabatic calorimeter of this type was described by Nernst in 1911. A series of different designs can be found in the list of references. Special equipment is needed for low-temperature calorimetry, below about 10 K. This equipment will not be discussed, and reference is made to the literature (see also Sect. 4.3.4). ... 

Modern calorimeters are more automated than the adiabatic calorimeter shown in Fig. 5.4, but the principle has not changed from the Nernst design. The calorimeter of Fig. 5.4 was mainly used for the measurement of specific heat capacities and heats of fusion of macromolecules. Under most favorable conditions it was capable of an accuracy of 0.1%. The temperature range of the instrument covered 170 to 600 K. 

The molar heat capacity Cp of LaSe was studied in an adiabatic Nernst calorimeter in the temperature range 90 to 390 K. Selected values for Cp and Cv in cal mol for temperatures... 

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