work production and present the second phase of the story in which Kelvin (1848–
1854) and Clausius (1850, 1854, 1865) succeeded in incorporating both energy
conservation and Carnot’s principle by introducing the conceptual differentiation of
heat into heat flow and entropy flow. Correspondingly, heat phenomena are to be
characterized by two fundamental principles: the principle of energy conservation
(this chapter) and the principle of unidirectionality (next two chapters).
It is significant to note that why the production of useful work cannot be
answered as an issue solely of the consumption of heat is because, in this understanding of heat according to the MEH, the nature of “consumption,” i.e., the cause,
is not addressed explicitly. Instead, the cause is to be identified with Carnot’s
transfer of heat. That is, the cause of the process is the purview of the second law of
thermodynamics (the principle of unidirectionality) which will be treated in
Chaps. 4, 5, 7, and 8.
The first law is sometimes called the principle of conservation of energy. This
principle is one of the few laws that we call them principles, including the entropy
principle as it will be treated in Chap. 5. Holton and Brush commented, “So simple,
general, and powerful are they that by the very extensiveness of their application the
conservation laws unify the various physical sciences within themselves and with
one another. Indeed, they have come to be called principles rather than laws, a
terminology that betrays that they are no longer merely summaries of experimental
facts but instead have become the starting points of scientific understanding itself.”
[6].
Problems
3:1 Show the relation, c p ¼ c V þ R between the isobaric and the isochoric molar
heat capacities, holds for an ideal gas based on the definitions of c p and c v ,
the definition of enthalpy, and the Joule’s law for ideal gases.
3:2 Calculate the internal energy change of a system which performs 34 J of
work and absorbs 32 calories of heat.
99:98 J
3:3 How many joule (J) of heat are absorbed by 3 kmols of an ideal gas
expanding isothermally* from the initial pressure of 5 atmospheres to the
final pressure of 3 atmospheres, at the temperature of 0 °C?
3480 kJ
3:4 A piston-cylinder device contains 0.95 kg of oxygen initially at a temperature of 27 °C and a pressure, due to the ambient atmospheric pressure and a
weight on the top of the piston, of 150 kPa. Heat is added to the gas until it
reaches a temperature of 627 °C. Determine the amount of heat added to the
gas during the process. How much of this heat in consumed (1) to increase
the internal energy of gas, (2) to perform work of compressing the ambient
atmosphere (assuming p 0 = 101.3 kPa), and (3) to increase the potential
3.11 The Story of Heat
57
1854) and Clausius (1850, 1854, 1865) succeeded in incorporating both energy
conservation and Carnot’s principle by introducing the conceptual differentiation of
heat into heat flow and entropy flow. Correspondingly, heat phenomena are to be
characterized by two fundamental principles: the principle of energy conservation
(this chapter) and the principle of unidirectionality (next two chapters).
It is significant to note that why the production of useful work cannot be
answered as an issue solely of the consumption of heat is because, in this understanding of heat according to the MEH, the nature of “consumption,” i.e., the cause,
is not addressed explicitly. Instead, the cause is to be identified with Carnot’s
transfer of heat. That is, the cause of the process is the purview of the second law of
thermodynamics (the principle of unidirectionality) which will be treated in
Chaps. 4, 5, 7, and 8.
The first law is sometimes called the principle of conservation of energy. This
principle is one of the few laws that we call them principles, including the entropy
principle as it will be treated in Chap. 5. Holton and Brush commented, “So simple,
general, and powerful are they that by the very extensiveness of their application the
conservation laws unify the various physical sciences within themselves and with
one another. Indeed, they have come to be called principles rather than laws, a
terminology that betrays that they are no longer merely summaries of experimental
facts but instead have become the starting points of scientific understanding itself.”
[6].
Problems
3:1 Show the relation, c p ¼ c V þ R between the isobaric and the isochoric molar
heat capacities, holds for an ideal gas based on the definitions of c p and c v ,
the definition of enthalpy, and the Joule’s law for ideal gases.
3:2 Calculate the internal energy change of a system which performs 34 J of
work and absorbs 32 calories of heat.
99:98 J
3:3 How many joule (J) of heat are absorbed by 3 kmols of an ideal gas
expanding isothermally* from the initial pressure of 5 atmospheres to the
final pressure of 3 atmospheres, at the temperature of 0 °C?
3480 kJ
3:4 A piston-cylinder device contains 0.95 kg of oxygen initially at a temperature of 27 °C and a pressure, due to the ambient atmospheric pressure and a
weight on the top of the piston, of 150 kPa. Heat is added to the gas until it
reaches a temperature of 627 °C. Determine the amount of heat added to the
gas during the process. How much of this heat in consumed (1) to increase
the internal energy of gas, (2) to perform work of compressing the ambient
atmosphere (assuming p 0 = 101.3 kPa), and (3) to increase the potential
3.11 The Story of Heat
57