Application of Cryogenic Calorimetry to Solid-State Chemistry
That a chemical scientist should concern himself intimately with low-temperature thermal studies may seem anomalous to those who in 1961 are relatively new to cryogenics. Yet, near the beginning of the present century when Kammerlingh Onnes at Leiden practically single-handedly kept the low-temperature research flag flying, the problems to be solved by such studies were mainly of interest to the physical chemist. Moreover, it was from this area that most of the fundamental contributions to the subject were made. The objective of Mernst’s work, which ultimately led to the important third law of thermodynamics, was one of finding a reference point for the numerical equations of chemical equilibrium. That the absolute zero of temperature was clearly recognized as the most suitable condition in which different substances might be compared with each other is not surprising since two hundred years earlier Amontons had visualized it as a state of rest. The concept of absolute zero as the absence of kinetic motion remained unchallenged in this era, and thus it appeared strange when Nernst concluded that the entropy, rather than the energy, was the variable which vanished with the absolute temperature. Although the true significance of the entropy function was initially veiled in mystery, the development of quantum mechanics and the realization that the phenomena observed at low temperatures were due to energy quantization shifted the focus of research from physical chemistry to pure physics.
KeywordsHeat Capacity Boron Nitride Plastic Crystal Excess Heat Capacity Vitreous Silica
Unable to display preview. Download preview PDF.
- 7.E. F. Westrum, Jr., et al. (unpublished data).Google Scholar
- 8.V.V. Tarasov, Dokiady Akad. Nauk SSSR, Vol. 46, 117 (1945);Google Scholar
- 8a.ibid., Vol. 54, 803 (1946);Google Scholar
- 8b.V.V. Tarasov, Zhur. Fiz. Khim., Vol. 24. 111 (1950); and others.Google Scholar
- 10.E. F. Westrum, Jr., “The Low Temperature Heat Capacity of Neutron-Irradiated Quartz, ” Proceedings of the IVe Congrès International du Verre, Paris, p. 396 (1956).Google Scholar
- 13.F. Koref, quoted by Nernst, op. cit.Google Scholar
- 18.E. Chang and E. F. Westrum, Jr. (unpublished data).Google Scholar
- 19.B.H. Justice and E.F. Westrum, Jr. (unpublished data).Google Scholar
- 21.R.D. Euler and E.F. Westrom, Jr., J. Phys. Chem., Vol. 65 [inpress] (1961).Google Scholar
- 22.R. D. Euler and E. F. Westrum, Jr. (unpublished data).Google Scholar
- 25.H.G. Carlson and E. F. Westrum, Jr. (unpublished data).Google Scholar