What is the 2nd Law of Thermodynamics, and is it important?
You have to complete BOTH part (A) and part (B) to get the credit.
Part (A)-“Energy” Survey:
-For this part, you will interview 6 persons (more than 16 years old)
and record their answers to some questions about “Energy” (Note that
there are no right or wrong answers).
-The persons you interview should NOT be classmates from this course,
but can be friends or relatives, classmates from other courses, of even
professors from other courses or from your high school! – However, you
should first ask them if no one else from this course has already asked
them to participate in this “Energy” Survey. If they have, then you have
to find another person to interview! (so there won’t be any repetition
-Each partner can interview 6 different persons, or they can be the same
6 for both.
-For each person, ask them if they would like to help you in a short
survey that you are conducting as a project for one of your college
The questions: (Remember to write down their answers!)
(1)-Is energy important in your life?
(2)-Why is energy important in your life, or why not?
(3)-In your own words, what is energy?
(4)-What is the 2nd Law of Thermodynamics, and is it important? (Why yes
or why not?) – If your respondent(s) answer to Question (4) is that the
2nd Law of Thermodynamics has to do Entropy, please also ask:
(4b) -What is Entropy?
(4c) -What does Entropy have to do with Energy?
(5)-What science courses (high-school or college) have you taken? (any
that they can remember).
-Provide each person’s name and phone and/or email so I can verify your
answers – Remember to include each of your respondents actual answers
with your report (not just a summary of all the answers).
-After you and your partner have interviewed ALL your persons, discuss
what YOU and your partner think the answers they have provided mean (at
least some 300 words).
-If you disagree with your partner on some point, write it out! (e.g.,
who says what).
Part (B)-The “Laws of Thermodynamics handout ( see handout below)
-You and your partner should discuss which part(s) of the “Laws of
Thermodynamics” handout you think are more important or more significant
to you (at least some 300 words).
-If you disagree with your partner, write it out! (e.g., who says what
The laws of thermodynamics.
William Antonio Boyle, 1987.
Thermodynamics, a branch of physics, is a relatively new science, its foundations having been developed between 1850 and 1900. As its name indicates, it dealt originally with the production of motion from heat, i.e., with the scientific understanding of the steam engine and later the internal combustion engine, one of the material bases of the industrial revolution.
It has been extraordinarily fruitful, and at present is considered among the fundamental principles of chemistry and physics (Lewis and Randall, 1961), of biology and ecology (Ehrlich et al, 1977), of economics (Georgescu, 1971), and of information theory (Weaver and Shannon, 1949). In general, thermodynamics studies the transformation of energy of different types (e.g., thermal, solar, mechanical, chemical, electrical, etc., or work, heat, kinetic, potential, etc.) from one kind to another.
Any transformation of energy must conform to certain universal restrictions, known as the first and second laws of thermodynamics. These are basic principles of nature to which no exceptions have ever been found (Smith and Van Ness, 1975).
The first law is very simple and is known as the “Law of conservation of energy” and it states that “Energy cannot be created or destroyed but can only be transformed.”
Energy can be defined as “the movement of mass on a microscopic or a macroscopic scale, or the capacity to cause such movement,” and the first law simply states that the quantity of energy must be conserved. What this means is that for any process in which energy is transformed, when one adds up all the quantities of the different forms of energy at the end, this sum has to be equal to the total amount of energy that was present at the beginning of the process, no more, and no less.
The second, or entropy law, places a restriction on the kinds of energy transformation that can take place, and is based on the simple fact that in nature heat always flows from a hot body to a cold body and never in the inverse direction. One consequence of this second law is that there is a quality of energy that places a limit on the transformation of that energy into useful work.
Energy of the movement of macroscopic bodies (kinetic energy) or any energy which can be transformed into movement of macroscopic bodies is usable energy, and is called free energy and can be transformed into useful work (That is, it is free to be transformed into work). On the other hand, if the energy cannot be transformed into movement of macroscopic bodies, it is unusable energy, and it is called bound energy and cannot be transformed into work.
For any given system, the least usable energy is thermal energy at the temperature of the environment; this energy cannot produce useful work at all. On the other hand, high-temperature thermal energy is largely usable and very versatile.
The second law can be stated in several equivalent ways; among these:
-“The entropy of the universe (or of any isolated system) can never decrease.”
That is, in any process the overall entropy has to increase or (at best) remain constant. This means that energy tends to degrade on its own, to transform into thermal energy at the temperature of the environment, even when it isn’t used to perform useful work, e.g., as in flashlight batteries. The second law can also be stated as:
-“A process whose only effect is a local lowering of entropy cannot exist.”
This means that a local lowering of entropy can occur, but only if there is a larger increase of entropy elsewhere, so that the net overall effect is an increase in entropy.
An important concept in thermodynamics is that of equilibrium. A system will be at equilibrium when it shows no further tendency to change its properties with the passing of time. So, another statement of the second law is: “With the passage of time all systems tend towards a state of equilibrium,” which means that an increase in entropy is equivalent to a coming closer to a state of equilibrium (Sandler, 1977).
For example, a glass of cold water in a hot room are not in thermal equilibrium, but, after a while the water gets warmer and finally its temperature will be the same as that of the room; they have reached a state of equilibrium.
All this means that to produce work, usable energy must be consumed and transformed into unusable energy, i.e., thermal energy at the temperature of the environment. And this means that free, usable energy is not recyclable, because each amount can be used to produce work essentially only once (Yes, energy can be re-used, but only the part that has not degraded to unusable energy).
This also implies that “nothing is ever really for free” (“there ain’t no such thing as a free lunch,” TANSTAAFL) because free, usable energy is the one that has economic value, and performing any work means that free energy has to be used up (Georgescu, 1971).
These concepts can also be applied to material bodies through statistical thermodynamics; usable, organized matter is of low entropy; in contrast, unusable, disorganized matter is of high entropy. So, organized matter, such as a building, an iron nail, or a live horse can be said to have low entropy; with the passing of time, due to the second law, this organization is lost: the building turns into ruins, the nail rusts and crumbles, and the animal dies and decomposes – their entropy has increased.
It can be seen that low entropy has economic value.
A simple way of observing entropy in action is to put a drop of food coloring dye into a glass of water. Initially, all the color is concentrated in a small region of the water, but, even if we don’t stir the water, after a certain amount of time the color will be uniformly dispersed in the water; an equilibrium has been attained. Of course, the dye can be concentrated again; but this would require an expenditure of free energy.
These concepts may be visualized in the operation of a heat engine (a simplified conceptual model of a steam engine). This is a machine that turns heat into work; it needs a source of high-temperature heat (usable energy) and a “sink” (a repository) for the discarded low-temperature heat (unusable energy).
The first law tells us that the quantity of high-temperature heat (thermal energy) that is consumed is equal to the sum of the quantity of work produced plus that of the discarded low-temperature heat: the total amount of energy is conserved.
The second law tells us that the net entropy has to increase, i.e., that the engine has to produce waste heat – or else the engine won’t work; and it tells us that usable energy is transformed into unusable energy.
As another example, one can imagine a coal-burning train going from one city to another. At the beginning, the coal represents low-entropy matter and energy, free energy available for producing work.
During the trip, useful work is performed, but the coal is transformed into ashes and combustion gases, high-entropy unusable materials. Again we can see the laws of thermodynamics in action. The quantities of matter and energy present originally have been conserved, but there has occurred an irrevocable qualitative change: entropy has increased.
It should be noted that the amount of coal would have degraded spontaneously, given enough time, even without human intervention – this intervention has simply speeded up the process (Georgescu, 1971).
These thermodynamic laws are some of the fundamental principles of biology and ecology (See Hutchinson, 1970; Oort, 1970; Prigogine and Nicolis, 1977; and Woodwell, 1970).
-Ehrlich, P.R., Ehrlich, A.H., and Holdren, J.P., Ecoscience: Population, Resources, Environment, Freeman, 1977.
-Georgescu-Roegen, N., The Entropy Law and the Economic Process, Harvard University Press, 1971.
-Hutchinson, G.E., “The biosphere”, Scientific American, Sept. 1970.
-Lewis, G.N., and Randall. M., Thermodynamics, 2/E, McGraw-Hill, 1961.
-Lepkowski, W., “The social thermodynamics of Ilya Prigogine”, Chemical & Engineering News, April 16, 1979.
-Oort, A.H., “The energy cycle of the earth”, Scientific American, Sept., 1970.
-Prigogine I. and Nicolis G., Self-Organization in Non-Equilibrium Systems, Wiley, 1977.
-Sandler, S.I., Chemical and Engineering Thermodynamics, Wiley, 1977.
-Smith, J.M. and Van Ness, H.C., Introduction to Chemical Engineering Thermodynamics, 3/E, McGraw-Hill, 1975.
-Weaver, W. and Shannon, C.E., The Mathematical Theory of Communication, University of Illinois Press, 1949.
-Woodwell, G.M., “The energy cycle of the biosphere”, Scientific American, Sept. 1970.