first law of thermodynamics wikipedia the free encyclopedia

first law of thermodynamics wikipedia the free encyclopedia

The history of thermodynamics is a fundamental strand in the history of physics , the history of chemistry , and the history of science in general. Owing to the relevance of thermodynamics in much of science and technology , its history is finely woven with the developments of classical mechanics , quantum mechanics , magnetism , and chemical kinetics , to more distant applied fields such as meteorology , information theory , and biology physiology , and to technological developments such as the steam engine , internal combustion engine , cryogenics and electricity generation.

The development of thermodynamics both drove and was driven by atomic theory. It also, albeit in a subtle manner, motivated new directions in probability and statistics ; see, for example, the timeline of thermodynamics.

The ancients viewed heat as that related to fire. In BC, the ancient Egyptians viewed heat as related to origin mythologies. The Empedoclean element of fire is perhaps the principal ancestor of later concepts such as phlogin and caloric.

Around BC, the Greek philosopher Heraclitus became famous as the "flux and fire" philosopher for his proverbial utterance: "All things are flowing. In the early modern period , heat was thought to be a measurement of an invisible fluid, known as the caloric. Bodies were capable of holding a certain amount of this fluid, leading to the term heat capacity , named and first investigated by Scottish chemist Joseph Black in the s.

In the 18th and 19th centuries, scientists abandoned the idea of a physical caloric, and instead understood heat as a manifestation of a system's internal energy. Today heat is the transfer of disordered thermal energy. Nevertheless, at least in English, the term heat capacity survives. In some other languages, the term thermal capacity is preferred, and it is also sometimes used in English. Atomism is a central part of today's relationship between thermodynamics and statistical mechanics.

Ancient thinkers such as Leucippus and Democritus , and later the Epicureans , by advancing atomism, laid the foundations for the later atomic theory [ citation needed ]. Horwood Publishing. Thermal Physics. Freeman Company. Branches of physics. Theoretical Computational Experimental Applied. Classical mechanics Acoustics Classical electromagnetism Optics Thermodynamics Statistical mechanics.

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Namespaces Article Talk. Views Read Edit View history. Help Community portal Recent changes Upload file. Download as PDF Printable version. Wikimedia Commons Wikiquote. Laws Zeroth First Second Third. Heat engines Heat pumps Thermal efficiency. System properties Note: Conjugate variables in italics Property diagrams Intensive and extensive properties. Material properties Property databases Specific heat capacity. Thermal expansion.

Equations Carnot's theorem Clausius theorem Fundamental relation Ideal gas law Maxwell relations Onsager reciprocal relations Bridgman's equations Table of thermodynamic equations. Caloric theory Theory of heat Vis viva "living force" Mechanical equivalent of heat Motive power.

Maxwell's thermodynamic surface Entropy as energy dispersal. Book Category. A timeline of events related to thermodynamics. An important idea in thermodynamics is that of a thermodynamic system. An example of a thermodynamic system is a brick. A brick is made up of many atoms which all have their own properties. All thermodynamic systems have two kinds of properties, extensive and intensive. In his ideal model, the heat of caloric converted into work could be reinstated by reversing the motion of the cycle, a concept subsequently known as thermodynamic reversibility.

Carnot, however, further postulated that some caloric is lost, not being converted to mechanical work. Hence, no real heat engine could realise the Carnot cycle 's reversibility and was condemned to be less efficient.

Though formulated in terms of caloric see the obsolete caloric theory , rather than entropy , this was an early insight into the second law. The Clausius theorem states that in a cyclic process. The equality holds in the reversible case [60] and the strict inequality holds in the irreversible case. The reversible case is used to introduce the state function entropy. This is because in cyclic processes the variation of a state function is zero from state functionality. Carnot's theorem states that all reversible engines operating between the same heat reservoirs are equally efficient.

In addition, a reversible heat engine operating between temperatures T 1 and T 3 must have the same efficiency as one consisting of two cycles, one between T 1 and another intermediate temperature T 2 , and the second between T 2 and T 3. This can only be the case if.

According to the Clausius equality , for a reversible process. So we can define a state function S called entropy, which for a reversible process or for pure heat transfer [15] satisfies.

With this we can only obtain the difference of entropy by integrating the above formula. For any irreversible process, since entropy is a state function, we can always connect the initial and terminal states with an imaginary reversible process and integrating on that path to calculate the difference in entropy.

Now reverse the reversible process and combine it with the said irreversible process. Applying the Clausius inequality on this loop,. An important and revealing idealized special case is to consider applying the Second Law to the scenario of an isolated system called the total system or universe , made up of two parts: a sub-system of interest, and the sub-system's surroundings. Whatever changes to dS and dS R occur in the entropies of the sub-system and the surroundings individually, according to the Second Law the entropy S tot of the isolated total system must not decrease:.

It is convenient to define the right-hand-side as the exact derivative of a thermodynamic potential, called the availability or exergy E of the subsystem,. The Second Law therefore implies that for any process which can be considered as divided simply into a subsystem, and an unlimited temperature and pressure reservoir with which it is in contact,. In sum, if a proper infinite-reservoir-like reference state is chosen as the system surroundings in the real world, then the Second Law predicts a decrease in E for an irreversible process and no change for a reversible process.

This expression together with the associated reference state permits a design engineer working at the macroscopic scale above the thermodynamic limit to utilize the Second Law without directly measuring or considering entropy change in a total isolated system.

Also, see process engineer. Those changes have already been considered by the assumption that the system under consideration can reach equilibrium with the reference state without altering the reference state. An efficiency for a process or collection of processes that compares it to the reversible ideal may also be found See second law efficiency.

This approach to the Second Law is widely utilized in engineering practice, environmental accounting , systems ecology , and other disciplines. Thus, a negative value of the change in free energy G or A is a necessary condition for a process to be spontaneous.

This is the most useful form of the second law of thermodynamics in chemistry, where free-energy changes can be calculated from tabulated enthalpies of formation and standard molar entropies of reactants and products. He was the first to realize correctly that the efficiency of this conversion depends on the difference of temperature between an engine and its environment.

Recognizing the significance of James Prescott Joule 's work on the conservation of energy, Rudolf Clausius was the first to formulate the second law during , in this form: heat does not flow spontaneously from cold to hot bodies. While common knowledge now, this was contrary to the caloric theory of heat popular at the time, which considered heat as a fluid. From there he was able to infer the principle of Sadi Carnot and the definition of entropy Established during the 19th century, the Kelvin-Planck statement of the Second Law says, "It is impossible for any device that operates on a cycle to receive heat from a single reservoir and produce a net amount of work.

The ergodic hypothesis is also important for the Boltzmann approach. It says that, over long periods of time, the time spent in some region of the phase space of microstates with the same energy is proportional to the volume of this region, i. Equivalently, it says that time average and average over the statistical ensemble are the same. There is a traditional doctrine, starting with Clausius, that entropy can be understood in terms of molecular 'disorder' within a macroscopic system.

This doctrine is obsolescent. In , the German physicist Rudolf Clausius stated what he called the "second fundamental theorem in the mechanical theory of heat " in the following form: [64]. From Wikipedia, the free encyclopedia. The English used in this article or section may not be easy for everybody to understand.

One precise statement of the zeroth law is that the relation of thermal equilibrium is an equivalence relation on pairs of thermodynamic systems. This means that a unique "tag" can be assigned to every system, and if the "tags" of two systems are the same, they are in thermal equilibrium with each other, and if different, they are not. This property is used to justify the use of empirical temperature as a tagging system.

Empirical temperature provides further relations of thermally equilibrated systems, such as order and continuity with regard to "hotness" or "coldness", but these are not implied by the standard statement of the zeroth law. If it is defined that a thermodynamic system is in thermal equilibrium with itself i. If a body C , be in thermal equilibrium with two other bodies, A and B , then A and B are in thermal equilibrium with one another.

This statement asserts that thermal equilibrium is a left- Euclidean relation between thermodynamic systems. If we also define that every thermodynamic system is in thermal equilibrium with itself, then thermal equilibrium is also a reflexive relation. Binary relations that are both reflexive and Euclidean are equivalence relations. Viscous fluid flow 3rd ed. McGraw Hill. Encyclopedia of physics: Principles of classical mechanics and field theory. Some textbooks throughout the 20th century have numbered the laws differently.

In some fields removed from chemistry, the second law was considered to deal with the efficiency of heat engines only, whereas what was called the third law dealt with entropy increases. Directly defining zero points for entropy calculations was not considered to be a law. Gradually, this separation was combined into the second law and the modern third law was widely adopted. From Wikipedia, the free encyclopedia.

Thermodynamics The classical Carnot heat engine. Classical Statistical Chemical Quantum thermodynamics. Zeroth First Second Third. System properties. Note: Conjugate variables in italics. The revised statement of the first law postulates that a change in the internal energy of a system due to any arbitrary process, that takes the system from a given initial thermodynamic state to a given final equilibrium thermodynamic state, can be determined through the physical existence, for those given states, of a reference process that occurs purely through stages of adiabatic work.

This statement is much less close to the empirical basis than are the original statements, [15] but is often regarded as conceptually parsimonious in that it rests only on the concepts of adiabatic work and of non-adiabatic processes, not on the concepts of transfer of energy as heat and of empirical temperature that are presupposed by the original statements. Largely through the influence of Max Born , it is often regarded as theoretically preferable because of this conceptual parsimony.

Born particularly observes that the revised approach avoids thinking in terms of what he calls the "imported engineering" concept of heat engines. Basing his thinking on the mechanical approach, Born in , and again in , proposed to revise the definition of heat.

Born observes that a transfer of matter between two systems is accompanied by a transfer of internal energy that cannot be resolved into heat and work components.

There can be pathways to other systems, spatially separate from that of the matter transfer, that allow heat and work transfer independent of and simultaneous with the matter transfer.

Energy is conserved in such transfers. The first law of thermodynamics for a closed system was expressed in two ways by Clausius. One way referred to cyclic processes and the inputs and outputs of the system, but did not refer to increments in the internal state of the system. The other way referred to an incremental change in the internal state of the system, and did not expect the process to be cyclic.

A cyclic process is one that can be repeated indefinitely often, returning the system to its initial state. Of particular interest for single cycle of a cyclic process are the net work done, and the net heat taken in or 'consumed', in Clausius' statement , by the system. In a cyclic process in which the system does net work on its surroundings, it is observed to be physically necessary not only that heat be taken into the system, but also, importantly, that some heat leave the system.

The difference is the heat converted by the cycle into work. In each repetition of a cyclic process, the net work done by the system, measured in mechanical units, is proportional to the heat consumed, measured in calorimetric units.

The constant of proportionality is universal and independent of the system and in and was measured by James Joule , who described it as the mechanical equivalent of heat. In a non-cyclic process, the change in the internal energy of a system is equal to net energy added as heat to the system minus the net work done by the system, both being measured in mechanical units.

This sign convention is implicit in Clausius' statement of the law given above. It originated with the study of heat engines that produce useful work by consumption of heat. Often nowadays, however, writers use the IUPAC convention by which the first law is formulated with work done on the system by its surroundings having a positive sign. With this now often used sign convention for work, the first law for a closed system may be written:. This convention follows physicists such as Max Planck , [22] and considers all net energy transfers to the system as positive and all net energy transfers from the system as negative, irrespective of any use for the system as an engine or other device.

Using either sign convention for work, the change in internal energy of the system is:. Work and heat are expressions of actual physical processes of supply or removal of energy, while the internal energy U is a mathematical abstraction that keeps account of the exchanges of energy that befall the system. Thus the term heat for Q means "that amount of energy added or removed by conduction of heat or by thermal radiation", rather than referring to a form of energy within the system.

Likewise, the term work energy for W means "that amount of energy gained or lost as the result of work". Internal energy is a property of the system whereas work done and heat supplied are not.

The law is of great importance and generality and is consequently thought of from several points of view. Most careful textbook statements of the law express it for closed systems. It is stated in several ways, sometimes even by the same author.

The first law of thermodynamics is a version of the law of conservation of energyadapted for thermodynamic processesdistinguishing two kinds first law of thermodynamics wikipedia the free encyclopedia transfer of energy, as heat and as thermodynamic workand relating them to a function of a body's state, called Internal energy. The law of conservation of energy first law of thermodynamics wikipedia the free encyclopedia that the total energy of an isolated system is constant; energy can facebook app free download for windows 10 transformed from one form to another, but can be neither created nor destroyed. For a thermodynamic process without transfer of matter, the first law is often formulated [1] [nb 1]. An equivalent statement is that perpetual motion machines of the first kind are impossible. For processes that include transfer of matter, a further statement is needed: 'With due account of the respective reference states of the systems, when two systems, which may first law of thermodynamics wikipedia the free encyclopedia of different chemical compositions, initially separated only by an impermeable wall, and otherwise isolated, are combined into a new system by the thermodynamic operation of removal of the wall, then. The first law of thermodynamics was developed empirically over about half a century. A main aspect of the struggle was to deal with the previously proposed caloric theory of heat. InGermain Hess stated a conservation law for the so-called 'heat of reaction' for chemical reactions. In best multiplayer free games on steam, Julius Robert von Mayer made a statement that has been rendered by Truesdell in the words "in a process at constant pressure, the heat used to produce expansion is universally first law of thermodynamics wikipedia the free encyclopedia with work", but this is not a general statement first law of thermodynamics wikipedia the free encyclopedia the first law. Free online games words with friends first full statements of the law came in from Rudolf Clausius [5] [6] and from William Rankine ; Rankine's statement is first law of thermodynamics wikipedia the free encyclopedia less distinct relative to Clausius'. The original nineteenth century statements of the first law of thermodynamics appeared in a conceptual framework in which transfer of energy as heat was taken as a primitive notionnot defined or constructed by the theoretical development of the framework, but rather presupposed as prior to it and already accepted. The primitive notion of heat was taken as empirically established, especially through calorimetry regarded as a subject in its own right, prior first law of thermodynamics wikipedia the free encyclopedia thermodynamics. Jointly primitive with this notion of heat were the notions of empirical temperature and thermal equilibrium. This framework also took as primitive the notion of transfer of energy as work. This framework did not presume a concept of energy in general, but regarded it as derived or synthesized from the prior notions of heat and work. By one author, this framework has been called the "thermodynamic" approach. The first explicit statement of the first law of thermodynamics, by Rudolf Clausius inreferred to cyclic thermodynamic processes. Clausius also stated the extreme dot to dot printables free in another form, referring to the existence of a function of state of the system, the internal energyand expressed it in terms of a differential equation for the increments of a thermodynamic process. Because of its definition in terms of increments, the value of the internal energy of a system is not uniquely defined. It is first law of thermodynamics wikipedia the free encyclopedia only up to an arbitrary additive constant of integration, which can be adjusted to give arbitrary reference zero levels. This non-uniqueness is in keeping with the abstract mathematical nature of the internal energy. first law of thermodynamics wikipedia the free encyclopedia The laws of thermodynamics define physical quantities, such as temperature, energy, and From Wikipedia, the free encyclopedia The first law of thermodynamics: When energy passes into or out of a system (as work, as heat, or with. Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their From Wikipedia, the free encyclopedia The first and second laws of thermodynamics emerged simultaneously in the s, primarily out of the. The second law of thermodynamics states that the total entropy of an isolated system can never From Wikipedia, the free encyclopedia The first law of thermodynamics provides the definition of the internal energy of a thermodynamic. First law of thermodynamics (fluid mechanics). From Wikipedia, the free encyclopedia. The history of thermodynamics is a fundamental strand in the history of physics, the history of The first quantitative research on the heat changes during chemical reactions was the Gibbs free energy equation, which suggested a measure of the amount of In , Walther Nernst stated the third law of thermodynamics. The zeroth law of thermodynamics states that if two thermodynamic systems are each in From Wikipedia, the free encyclopedia. Jump to The underlying physical meaning was perhaps first clarified by Maxwell in his textbook. There are four laws of thermodynamics that say how energy can be moved between two First law of thermodynamics. Timeline of thermodynamics. From Wikipedia, the free encyclopedia. Talk:First law of thermodynamics. From Wikipedia, the free encyclopedia. Jump to navigation Jump to search. This is the talk. From Wikipedia, the free encyclopedia The second law of thermodynamics says that when energy changes from one form to another form, of a statement of the Second Law of Thermodynamics to music, called "First and Second Law. The Refrigerator and the Universe. The etymology of thermodynamics has an intricate history. Bibcode : PhRv Thermodynamics Heat engines. Categories : Laws of thermodynamics Scientific laws. Another example: In the Sun or any star , Nuclear Fusion changes mass into heat and light Electromagnetic Radiation , which travels to Earth and is used by plants to create food chemical energy via photosynthesis , which can be eaten by animals allowing them to move kinetic energy. State may be thought of as the instantaneous quantitative description of a system with a set number of variables held constant. Kazakov, Andrei; Muzny, Chris D. Transactions of the Connecticut Academy of Arts and Sciences. In mechanics , for example, energy transfer equals the product of the force applied to a body and the resulting displacement. By , as formalized in the works of those such as Rudolf Clausius and William Thomson , two established principles of thermodynamics had evolved, the first principle and the second principle, later restated as thermodynamic laws. A final condition of a natural process always contains microscopically specifiable effects which are not fully and exactly predictable from the macroscopic specification of the initial condition of the process. In an equilibrium state there are no unbalanced potentials, or driving forces, between macroscopically distinct parts of the system. In the various theoretical descriptions of thermodynamics these laws may be expressed in seemingly differing forms, but the most prominent formulations are the following. first law of thermodynamics wikipedia the free encyclopedia