TABLE OF CONTENTS Calorimetry involves the measurement of the extensive quantity heat. Its name derives from the middle of the 18 th century when heat was called the "caloric," as described in Sects. 1.1.1 and 2.1.1. As the main thermal-analysis method, calorimetry is discussed in this and the following two sections, covering classical calorimetry in Sect. 4.2, differential scanning calorimetry (DSC) in Sect. 4.3, and the more recent temperature-modulated calorimetry (TMC) in Sect. 4.4.
The SI unit of heat, as well as of work and energy is the joule, J as summarized in Fig. 2.3. Its dimension is expressed in [kg m 2 s ?2]. Heat and work describe the energy exchanged between thermodynamic systems, as discussed in Sect. 2.1.5 with the equation ?q + ?w = dU. An earlier, empirical unit, the "calorie," was based on the specific heat capacity of water (1 cal thermochemical = 4.184 J). Since the early 20 th century, however, energy, heat, and work are more precisely determined in joules, making the calorie a superfluous unit. The calorie is not part of the SI units and should be abandoned. All modern calorimetry is ultimately based on a comparison with heat generated by electrical work.
Almost all calorimetry is carried out at constant pressure, so that the measured heat is the change in enthalpy, as discussed in Chap. 2. The thermodynamic functions that describe a system at constant pressure are listed in Fig. 4.25. These...
