1.10 Quantity of Heat
Temperature is the quantitative measure of the degree of heat, not the quantity of
heat itself. The traditional method of the determination of the quantity of heat is
called calorimetry, which is treated in Chap. 2.
According to the mechanical equivalent of heat (MEH, to be introduced in
Chap. 3), any change in heat is quantitatively linked to a corresponding change in
mechanical energy. The method for the determination of the quantity of heat by
connecting it to the mechanical energy is treated in Chap. 3. Correspondingly, heat
has been considered to be a form of energy—i.e., heat is defined as
Definition of heat : heat is energy in transition; or, heat is a form of energy that moves from
a hotter object to a colder one.
This “energetic” definition of heat offers too narrow an understanding of heat,
one associated with the widely accepted but erroneous interpretation of MEH as
universal interconvertibility (see Sect. 8.6.2), which gave rise to the notion of
“consumption of heat” as the cause of producing work.
The true meaning of MEH will be critically studied in Chaps. 3–8, in which a
case will be made that the interpretation of MEH that is associated with this definition of heat amounts to accord the first law of thermodynamics preeminence over
the second law as it is presently formulated (as it will be discussed in Chap. 8).
Without a complete second law, it is not possible to comprehend heat adequately.
Correspondingly, this disquisition takes the position that the aforementioned definition of heat merely captures one aspect of heat, denoted as Q (see Chaps. 2 and 3),
and proposes the definition of heat (as it was recorded at the beginning of this
chapter) in Sect. 5.6, with further elaboration for the meaning of heat when a more
precise interpretation of MEH is given in Chap. 8.
Problems
1:1 Calculate the work (in unit J) performed by a body expanding* from an
initial volume of 3 L (1 L = 10
−3 m
3 ) to a final volume of 4 L at the pressure
of 2.5 atm (1 atm = 101, 325 Pa).
253.3 J
1:2 Calculate the pressure of 0.03 kilograms of hydrogen (hydrogen molar mass
M hydrogen = 2.016 kg/kmole) inside a container of 1 m
3 at the temperature of
18 °C.
36.02 kPa
1:3 Calculate the density and specific volume of nitrogen (M nitrogen = 28.013) at
the temperature of 0 °C and the pressure of 1 atm.
1.25 kg/m
3 (0.0446 kmol/m
3 ; 22.4 m
3 /kmole).
22
1 Introduction: Temperature and Some Comment on Work
Temperature is the quantitative measure of the degree of heat, not the quantity of
heat itself. The traditional method of the determination of the quantity of heat is
called calorimetry, which is treated in Chap. 2.
According to the mechanical equivalent of heat (MEH, to be introduced in
Chap. 3), any change in heat is quantitatively linked to a corresponding change in
mechanical energy. The method for the determination of the quantity of heat by
connecting it to the mechanical energy is treated in Chap. 3. Correspondingly, heat
has been considered to be a form of energy—i.e., heat is defined as
Definition of heat : heat is energy in transition; or, heat is a form of energy that moves from
a hotter object to a colder one.
This “energetic” definition of heat offers too narrow an understanding of heat,
one associated with the widely accepted but erroneous interpretation of MEH as
universal interconvertibility (see Sect. 8.6.2), which gave rise to the notion of
“consumption of heat” as the cause of producing work.
The true meaning of MEH will be critically studied in Chaps. 3–8, in which a
case will be made that the interpretation of MEH that is associated with this definition of heat amounts to accord the first law of thermodynamics preeminence over
the second law as it is presently formulated (as it will be discussed in Chap. 8).
Without a complete second law, it is not possible to comprehend heat adequately.
Correspondingly, this disquisition takes the position that the aforementioned definition of heat merely captures one aspect of heat, denoted as Q (see Chaps. 2 and 3),
and proposes the definition of heat (as it was recorded at the beginning of this
chapter) in Sect. 5.6, with further elaboration for the meaning of heat when a more
precise interpretation of MEH is given in Chap. 8.
Problems
1:1 Calculate the work (in unit J) performed by a body expanding* from an
initial volume of 3 L (1 L = 10
−3 m
3 ) to a final volume of 4 L at the pressure
of 2.5 atm (1 atm = 101, 325 Pa).
253.3 J
1:2 Calculate the pressure of 0.03 kilograms of hydrogen (hydrogen molar mass
M hydrogen = 2.016 kg/kmole) inside a container of 1 m
3 at the temperature of
18 °C.
36.02 kPa
1:3 Calculate the density and specific volume of nitrogen (M nitrogen = 28.013) at
the temperature of 0 °C and the pressure of 1 atm.
1.25 kg/m
3 (0.0446 kmol/m
3 ; 22.4 m
3 /kmole).
22
1 Introduction: Temperature and Some Comment on Work