Boltzmanns microscopic formula for entropy is introduced and used to explain irreversibility. Entropy changes and the third law of thermodynamics. Che 212 lecture note entropy second law of thermodynamics. A gas can be heated to the temperature of the bottom of the pond, and allowed to cool as it blows through a turbine. The second law of thermodynamics and entropy thermodynamics. The thermodynamics functions, entropy and free energy, those arise from the second law of thermodynamics play pivotal role in all branches of pure and applied science physics, chemistry, biology and materials science. If someone points out to you that your pet theory of the universe is in disagreement with maxwells equations then so much the worse for maxwells equations.
The second law, like the first law, is characterized by both qualitative concepts and. The third law the third law of thermodynamics says. Physical chemistry 1 1 lecture 9 the second law of thermodynamics 9. Thermodynamics 1 1 1st year thermodynamic lectures dr mark r. Last time the maxwellboltzmann distribution distribution of speeds the second law of thermodynamics. These two approaches are interwoven in this presentation. Heat engines, entropy, and the second law of thermodynamics. Video created by university of manchester for the course introduction to physical chemistry. Entropy differs from energy in that entropy does not obey a conservation law. A guide to entropy and the second law of thermodynamics. Entropy production at the very core of the second law of thermodynamics we find the basic distinction between reversible and irreversible processes 1. Pdf this paper is a nontechnical, informal presentation of our theory of the second law of thermodynamics as a law that is independent of statistical.
This section provides the lecture notes for the course along with the schedule of lecture topics. Pdf the following content is provided under a creative commons license. We have learned about the first law of thermodynamics, which is essentially the law of. Entropy and the second law of thermodynamics electric.
Unfortunately, in everyday language, spontaneous suggests something that. Transfer of heat from the system to its environment is spontaneous if entropy production is positive, requiring that the system has a higher temperature. We observe that some things happen on their own, while others require some outside work or effort to make them happen. The entropy of a pure, perfect crystal at 0 k is zero. A process can occur when and only when it satisfies both the first and the second laws of thermodynamics. Gases expand from a high pressure to a low pressure. Abata the second law, like the first law, is characterized by both qualitative concepts and quantitative analysis mathematics. The entropyof an isolated system can only increase. Entropy according to boltzmann university of pennsylvania. Energy transfer, entropy and second law of thermodynamics, thermodynamic functions and potentials, microcanonical statistical mechanics, canonical statistical mechanics, phase changes of a pure substance, binary solutions. Chapter 5 2 thermal energy reservoir a thermal energy reservoir is a hypothetical body that can supplyor absorbfinite amounts of heat without undergoing any change in temperature large bodies of. The overall change of the internal energy u hence vanishes. S is the transfer of entropy across the boundaries of the system, and the second d i s, is the entropy produced within the system.
Where, for irreversible system t dq ds and, for reversible system dq ds t for a closed system in which only reversible pv work is involved dw. Specific examples are given to calculate the entropy change for a number of different processes. The second law of thermodynamics the second law of thermodynamics can be stated in a number of equivalent ways. The entropy of an isolated system can never decrease. The second law also asserts that energy has a quality. Classical thermodynamics department of applied mathematics. Discuss the importance of second law of thermodynamics. Entropy on a microscopic scale the first law of thermodynamics, which we studied in chapter. The joint system of a system and its environment is called universe. After the first three chapters, which refer to key concepts first and second laws, energy, entropy, work, heat.
Total energy conservation, viz the first law of thermodynamics, dictates that. An important implication of this law is that heat transfers energy spontaneously from higher to lowertemperature objects, but never spontaneously in the reverse direction. A measure of disorder entropy and the clausius inequality the second law of thermodynamics leads to the definition of a new property called entropy, a quantitative measure of microscopic disorder for a system. The greater the number of possible microstates for a system, the greater the disorder and the higher the entropy. Because of this property, the change in entropy is sometimes called othe arrow of time. It would be very convenient to be able to convert heat into work merely by reversing a process like friction. Second law of thermodynamics and entropy reversibility and the second law figure 1. The second law of thermodynamics states that the total entropy of a system either increases or remains constant in any spontaneous process. In many books, the wordspontaneousis used for this concept. S heatt thermal energy goes toward increasing the entropy second law of thermodynamics the entropy of a closed system always increases. Entropy and the second law of thermodynamics the conservation of energy law allows energy to flow bidirectionally between its various forms.
The first law of thermodynamics is a statement about energy conservation, while the second is a statement about stable thermal equilibrium. This is episode 4 from an introduction to chemical change and thermodynamics by professor george porter, f. A thermodynamically allowed process could occur, but may not for kinetic reasons. Physical processes in nature can proceed toward equilibrium spontaneously. As the pendulum swings useful energy is lost to increasing the random motion of the. Entropy is a measure of energy that is no longer available to perform useful work within the current environment. Entropy and the second law of thermodynamics electric and. A guide to entropy and the second law of thermodynamics elliott h. This law tells us nothing about the spontaneity of physical and chemical transformations. Second law of thermodynamics a process will not occur unless it satisfies boththe first and the second laws of thermodynamics spring 2003 ece309. The entropy of the world increases clausius 1850 thermodynamics paul and tatiana ehrenfest, the conceptual foundation of the statistical approach in mechanics, german edition, teubner, leipzig, 1912. Concept of entropy the law that entropy always increases, holds, i think, the supreme position among the laws of nature. Second law of thermodynamics entropy change of the system does not correctly predict spontaneity.
Several competing statements and practical corollaries of the second law have been developed over. Probability, the second law of thermodynamics and entropy. The second law of thermodynamics and statistical mechanics. The fi rst law of thermodynamics, that energy is conserved, just ells us what can happen. Fundamental equations of thermodynamics 1 the combined first and second law from the first law. The second law of thermodynamics helps us to identifying the direction of processes. This leads ultimately to the introduction of entropy s and the formulation of the second law of thermodynamics. There are several ways in which the second law of thermodynamics can be stated. Entropy and 2nd law of thermodynamics einsteins view. Chapter 4 entropy and the second law of thermodynamics. In particular, we have discussed heat transfer between the different objects.
For combined system and surroundings, entropy never decreases. This definition of entropy is entirely equivalent to boltzmanns later. Second law of thermodynamics simon fraser university. We have learned about the first law of thermodynamics, which is essentially the law. If we consider only the conservation of energy, we might think that heat energy, such as that in the vibrational motions of molecules, might provide a goodly supply of useful energy. The second law the second law of thermodynamics the entropy of the universe increases in any thermodynamically allowed process. These are lecture notes for ame 20231, thermodynamics. This is the clausius statement of the second law of thermodynamics. The second law also asserts that energy has quality as well as quantity, whereas, the first law is concerned with the quantity of energy and the transformations of energy from one form to another with no regard to its quality. One correct statement of the second law of thermodynamics is. For example in a pendulum, energy continually goes tofrom kinetic energy and potential energy. Introduce and define thermodynamic properties such as internal energy and enthalpy. The second law of thermodynamics asserts that it is not. Lieb and jakob yngvason t his article is intended for readers who,like us, were told that the second law of thermodynamics is one of the major achievements of the nineteenth centurythat it is a logical, perfect, and unbreakable law but who were unsatisfied with the.
Second year second semester entropy changes and the third law of thermodynamics entropy s is a thermodynamic property of all substances that is proportional to their degree of disorder. For example, a certain amount of gas will spontaneously expand to fill the volume of its container. The second law of thermodynamics if a process occurs in a closed system, the entropy of the system increases for irreversible processes and remains constant for reversible processes. This module explores the second law of thermodynamics and entropy, the second law of thermodynamics and spontaneity, the second law of. In this chapter, we discuss the statements and consequences of the second law of thermodynamics. Rather than enjoying a fine ebook considering a mug of coffee in the.
When the rubber band is at its rest length, the polymers are coiled up. Second law of thermodynamics and can be stated as follows. The rubber band rubber consists of crosslinked polymer chains. This law states that a change in internal energy in a system can occur as a result of energy. For irreversible processes,the entropy of a closed system always increases. Isp209s8 lecture 12 3 entropy entropy is a measure of the number of ways a system can be arranged.
Entropy and the second law of thermodynamics the second law of thermodynamics defines a state variable called entropy s to quantify the direction of natural processes. Preserving the quality of energy is a major concern of engineers. The laws of thermodynamics first law the energy of the isolated system is conserved. Conservation of energy second law the entropy of the isolated system increases in all real processes and is conserved in reversible theoretical processes. The second law of thermodynamics the second law of thermodynamics states that processes occur in a certain direction, not in just any direction. Spontaneous transfer of heat from a cold body to a hot body is impossible. S associated with an irreversible process in a closed system is always greater than or equal to. Boltzmann also showed that there were three contributions to entropy. Phys 200 lecture 24 the second law of thermodynamics. The energy of the universe is constant energy is conserved. The second law of thermodynamics this is a consequence of probability. Ssurroundings entropy and heat simplest case is a process which. The focus of the lecture is the concept of entropy. Entropy predicts the direction of spontaneous processes, and determines whether they are irreversible or impossible, despite obeying the.
The second law pr9vides these types of guidance and thus moe strongly distinguishes thermodynamics from its subset banches of physics, sllch as mechanics. Lecture notes on thermodynamics university of notre. Rankine, 1859, a manual of the steam engine and other. Applies to a crystal of any substance note that this is a fairly hypothetical limit. The entropy can only increase or, in the limit of a reversible process, remain. Che 212 lecture note free download as powerpoint presentation. Entropy s is a thermodynamic state function which can be. Chem 467 supplement to lecture 29 second law of thermodynamics, entropy spontaneity we are all familiar with the concept of spontaneity. Overview entropy macroscopic perspective reversible and irreversible processes reversible process.
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