What is an irreversible change in thermodynamics?
In thermodynamics, a change in the thermodynamic state of a system and all of its surroundings cannot be precisely restored to its initial state by infinitesimal changes in some property of the system without expenditure of energy. A system that undergoes an irreversible process may still be capable of returning to its initial state.
What are irreversible processes?
What are Irreversible Processes? An irreversible process can be defined as a process in which the system and the surroundings do not return to their original condition once the process is initiated. Taking an example of an automobile engine, that has travelled a distance with the aid of fuel equal to an amount ‘x’.
What happens to entropy during the irreversible process?
During the irreversible process the various states of the system on the path of change from initial state to final state are not in equilibrium with each other. During the irreversible process the entropy of the system increases decisively and it cannot be reduced back to its initial value.
How is the second law of thermodynamics used to determine reversible processes?
The second law of thermodynamics can be used to determine whether a process is reversible or not. Intuitively, a process is reversible if there is no dissipation. For example, Joule expansion is irreversible because initially the system is not uniform. Initially, there is part of the system with gas in it, and part of the system with no gas.
What is irreversible process in thermodynamics with example?
An irreversible process can be defined as a process in which the system and the surroundings do not return to their original condition once the process is initiated. Take an example of an automobile engine that has travelled a distance with the aid of fuel equal to an amount 'x'.
What is meant by irreversible process in thermodynamics?
Irreversible processes are actual processes carried out in finite time with real substances with internal temperature, pressure, and/or velocity changes causing energy dissipation, such as viscous dissipation.
What is reversible and irreversible process in thermodynamics?
In terms of thermodynamics, a reversible process is where the participants go back to its initial form by inculcating minor or negligible changes in their surroundings. Contrarily, an irreversible process is a naturally occurring phenomenon, which does not go back to its original state.
What is reversible and irreversible process give example?
Ans: The changes which can be brought back to their original form are known as reversible changes. For example, melting of ice, expansion, or compression of spring. And irreversible changes are those changes in which the matter cannot be brought back to its original state. For example, burning of fuel, etc.
What is difference between reversible and irreversible process?
Difference between reversible and irreversible process Reversible process can be reversed in order to obtain the initial state of a system. Irreversible process cannot be reversed. There is no loss of energy in the reversible process. In this process, permanent loss of energy takes place.
What are the example of irreversible?
Examples of irreversible changesBurning: When we burn a piece of paper or wood, it turns to ash and smoke. We cannot obtain paper and wood from the ash again.Cooking: We use heat for cooking, right? Once we cook our eggs, we cannot uncook them. ... Rusting of iron: You must have seen rusting of iron.
What is irreversible process in thermodynamics class 11?
An irreversible process is a thermodynamic process that departs from equilibrium. In terms of pressure and volume, it occurs when the pressure (or the volume) of a system changes dramatically and instantaneously that the volume (or the pressure) do not have the time to reach equilibrium.
Why is heat transfer irreversible?
Because of the finite temperature difference between the two interacting bodies, the energy transfer is an irreversible process. This irreversibility leads to a loss in the available energy.
What defines a reversible process?
A reversible process is defined as a process in which the system and surroundings can be returned to the original conditions from the final state without producing any changes in the thermodynamics properties of the universe, if the process is reversed.
Which of the following is irreversible process?
Heat transfer by conduction: Heat transfer by conduction takes place when there is a finite temperature difference between the two interacting bodies, so the heat transfer by conduction is an irreversible process.
Which is the example of irreversible process Mcq?
any natural process carried out with a finite gradient is an irreversible process, ∴ heat engine and internal combustion engine are irreversible devices.
What is meant by irreversible adiabatic process?
For an ideal gas, the temperature remains constant because the internal energy only depends on temperature in that case. Since at constant temperature, the entropy is proportional to the volume, the entropy increases in this case, therefore this process is irreversible.
What is meant by reversible process?
A reversible process is defined as a process in which the system and surroundings can be returned to the original conditions from the final state without producing any changes in the thermodynamics properties of the universe, if the process is reversed.
Why is heat transfer irreversible?
Because of the finite temperature difference between the two interacting bodies, the energy transfer is an irreversible process. This irreversibility leads to a loss in the available energy.
What is irreversible adiabatic process?
As the name suggests, the process can't be traced back to its original state. During an irreversible adiabatic process of expansion. There will be a change in entropy because of frictional dissipation. Irreversible expansion cannot be performed at equilibrium.
What is a reversible process?
Reversible process can be turned back such that both the system and the surroundings return to their original states, with no other change anywhere...
What is an irreversible process?
An irreversible process can be defined as a process in which the system and the surroundings do not return to their original condition once the pro...
Give some examples of reversible processes.
Extension of springs Slow adiabatic compression or expansion of gases The frictionless motion of solids Slow isothermal compression or expansion of...
Give some examples of irreversible processes.
Relative motion with friction Throttling Heat transfer Diffusion
What is irreversible adiabatic process?
Irreversible adiabatic process: If the cylinder is a perfect insulator, the initial top-left state cannot be reached anymore after it is changed to the one on the top-right. Instead, the state on the bottom left is assumed when going back to the original pressure because energy is converted into heat.
What is a process that is not reversible called?
e. In science, a process that is not reversible is called irreversible. This concept arises frequently in thermodynamics . In thermodynamics, a change in the thermodynamic state of a system and all of its surroundings cannot be precisely restored to its initial state by infinitesimal changes in some property of the system without expenditure ...
What are the events that can be reversible?
Events to which the self-organizing capacities of organisms, species or other complex systems can adapt, like minor injuries or changes in the physical environment are reversible. However, adaptation depends on import of negentropy into the organism, thereby increasing irreversible processes in its environment.
What is the difference between reversible and irreversible?
The difference between reversible and irreversible events has particular explanatory value in complex systems (such as living organisms, or ecosystems ). According to the biologists Humberto Maturana and Francisco Varela, living organisms are characterized by autopoiesis, which enables their continued existence. More primitive forms of self-organizing systems have been described by the physicist and chemist Ilya Prigogine. In the context of complex systems, events which lead to the end of certain self-organising processes, like death, extinction of a species or the collapse of a meteorological system can be considered as irreversible. Even if a clone with the same organizational principle (e.g. identical DNA-structure) could be developed, this would not mean that the former distinct system comes back into being. Events to which the self-organizing capacities of organisms, species or other complex systems can adapt, like minor injuries or changes in the physical environment are reversible. However, adaptation depends on import of negentropy into the organism, thereby increasing irreversible processes in its environment. Ecological principles, like those of sustainability and the precautionary principle can be defined with reference to the concept of reversibility.
What is the paradox of microanalysis?
However, a paradox arose when attempting to reconcile microanalysis of a system with observations of its macrostate. Many processes are mathematically reversible in their microstate when analyzed using classical Newtonian mechanics. This paradox clearly taints microscopic explanations of macroscopic tendency towards equilibrium, such as James Clerk Maxwell 's 1860 argument that molecular collisions entail an equalization of temperatures of mixed gases. From 1872 to 1875, Ludwig Boltzmann reinforced the statistical explanation of this paradox in the form of Boltzmann's entropy formula stating that as the number of possible microstates a system might be in, increases, the entropy of the system increases and it becomes less likely that the system will return to an earlier state. His formulas quantified the work done by William Thomson, 1st Baron Kelvin who had argued that:
Who discovered irreversible systems?
Another explanation of irreversible systems was presented by French mathematician Henri Poincaré. In 1890, he published his first explanation of nonlinear dynamics, also called chaos theory. Applying the chaos theory to the second law of thermodynamics, the paradox of irreversibility can be explained in the errors associated with scaling from microstates to macrostates and the degrees of freedom used when making experimental observations. Sensitivity to initial conditions relating to the system and its environment at the microstate compounds into an exhibition of irreversible characteristics within the observable, physical realm.
Is Joule expansion irreversible?
Intuitively, a process is reversible if there is no dissipation. For example, Joule expansion is irreversible because initially the system is not uniform. Initially, there is part of the system with gas in it, and part of the system with no gas. For dissipation to occur, there needs to be such a non uniformity.
What is a Reversible Process?
The process in which the system and surroundings can be restored to the initial state from the final state without producing any changes in the thermodynamics properties of the universe is called a reversible process. In the figure below, let us suppose that the system has undergone a change from state A to state B. If the system can be restored from state B to state A, and there is no change in the universe, then the process is said to be a reversible process. The reversible process can be reversed completely and there is no trace left to show that the system had undergone thermodynamic change.
What are the two main categories of thermodynamics?
changes. The second law of thermodynamics enables us to classify all the processes under two main categories: reversible or ideal processes and irreversible or natural processes.
What are the two conditions for a reversible process to occur?
Firstly, the process should occur in infinitesimally small time and secondly all of the initial and final state of the system should be in equilibrium with each other.
What happens during irreversible process?
During the irreversible process the entropy of the system increases decisively and it cannot be reduced back to its initial value. The phenomenon of a system undergoing irreversible process ...
Why is the irreversible process called the natural process?
The irreversible process is also called the natural process because all the processes occurring in nature are irreversible processes. The natural process occurs due to the finite gradient between the two states of the system. For instance, heat flow between two bodies occurs due to the temperature gradient between the two bodies;
What is the phenomenon of undergoing reversible change?
The phenomenon of undergoing reversible change is also called reversibility. In actual practice the reversible process never occurs, thus it is an ideal or hypothetical process.
What is the phenomenon of a system undergoing irreversible process called?
The phenomenon of a system undergoing irreversible process is called as irreversibility.
What are Irreversible Processes?
An irreversible process can be defined as a process in which the system and the surroundings do not return to their original condition once the process is initiated. Taking an example of an automobile engine, that has travelled a distance with the aid of fuel equal to an amount ‘x’. During the process, the fuel burns to provide energy to the engine, converting itself into smoke and heat energy. We cannot retrieve the energy lost by the fuel and cannot get back the original form. There are many factors due to which the irreversibility of a process occurs, namely:
What causes irreversibility of a process?
There are many factors due to which the irreversibility of a process occurs, namely: The unrestrained expansion of the fluid which prevents from regaining the original form of the fuel Heat transfer through a finite temperature, the reverse of which is not possible as the forward process, in this case, is spontaneous.
Can a process be reversible?
As we know, in reality, no such processes as reversible processes can exist. Thus, the reversible processes can easily be defined as idealizations or models of real processes, on which the limits of the system or device are to be defined.
Is intermixing spontaneous?
Mixing of two different substances which cannot be separated as the process of intermixing is again spontaneous in nature, the reverse of which is not feasible.
Is a thermodynamic process reversible?
As we know, in reality, no such processes as reversible processes can exist.
What is an isentropic process?
An isentropic process is a thermodynamic process in which the entropy of the fluid or gas remains constant. It means the isentropic process is a special case of an adiabatic process in which there is no transfer of heat or matter. It is a reversible adiabatic process. An isentropic process can also be called a constant entropy process. In engineering, such an idealized process is very useful for comparison with real processes.
How to approximate reversible processes?
One way to make real processes approximate reversible processes is to carry out the process in a series of small or infinitesimal steps or infinitely slowly so that the process can be considered a series of equilibrium states . For example, heat transfer may be considered reversible due to a small temperature difference between the system and its surroundings. But real processes are not done infinitely slowly. Reversible processes are a useful and convenient theoretical fiction but do not occur in nature. For example, there could be turbulence in the gas. Therefore, heat engines must have lower efficiencies than limits on their efficiency due to the inherent irreversibility of the heat engine cycle they use.
Why do heat engines have lower efficiencies than limits?
For example, there could be turbulence in the gas. Therefore, heat engines must have lower efficiencies than limits on their efficiency due to the inherent irreversibility of the heat engine cycle they use .
What is irreversible thermodynamics?
In thermodynamics, an irreversible process is defined as a process that cannot be reversed, which cannot return both the system and the surroundings to their original conditions.
Does entropy decrease in a natural process?
The entropy of any isolated system never decreases. In a natural thermodynamic process, the sum of the entropies of the interacting thermodynamic systems increases.
What is irreversible process?
Irreversible Process: An irreversible process is a type of process in which the driving force is much greater than the opposing force. It is a very fast process and takes a very little time to complete. In case of irreversible expansion, P gas is much greater than P ext (P gas >> P ext ).
What is it called when the opposing force is increased by an infinitesimally small amount?
If the opposing force is increased by an infinitesimally small amount, the process returns back to its previous state. Therfore, it is called reversible .
Is P gas greater than P ext?
For a reversible expansion, P gas is infinitesimally greater than P ext. For a reversible compression, P ext is infinitesimally greater than P gas. Work done in a reversible process is given by: Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
What are some possible solutions for frictionless movement?
Some possible solutions are frictionless movement; restrained compression or expansion; energy transfer as heat due to infinitesimal temperature nonuniformity; electric current flow through a zero resistance; restrained chemical reaction; and mixing of two samples of the same substance at the same state.
What is the difference between irreversible and reversible?
A reversible process is one in which both the system and its environment can return to exactly the states they were in by following the reverse path. An irreversible process is one in which the system and its environment cannot return together to exactly the states that they were in.
What is the necessary condition for a reversible process?
The necessary condition for a reversible process is therefore the quasi-static requirement. Note that it is quite easy to restore a system to its original state; the hard part is to have its environment restored to its original state at the same time.
Why do we feel cold when we hold ice?
For example, when we hold a few pieces of ice in our hands, we feel cold because heat has left our hands into the ice. The opposite is true when we hold one end of a metal rod while keeping the other end over a fire.
How to tell if a process is irreversible?
The sign of an irreversible process comes from the finite gradient between the states occurring in the actual process. For example, when heat flows from one object to another, there is a finite temperature difference (gradient) between the two objects.
What is a reversible process?
A reversible process is a process in which the system and environment can be restored to exactly the same initial states that they were in before the process occurred, if we go backward along the path of the process. The necessary condition for a reversible process is therefore the quasi-static requirement.
Why is half of the container under vacuum?
Because half of the container is under vacuum before the gas expands there, we do not expect any work to be done by the system—that is, W = 0 W = 0 —because no force from the vacuum is exerted on the gas during the expansion. If the container is thermally insulated from the rest of the environment, we do not expect any heat transfer to ...
What is reversible process?
In thermodynamics, a reversible process is defined as a process that can be reversed by inducing infinitesimal changes to some property of the system, and in so doing leaves no change in either the system or surroundings. During reversible process the entropy of the system does not increase and the system is in thermodynamic equilibrium ...
What is Carnot's principle?
What Carnot’s principle states about reversible processes: No engine can be more efficient than a reversible engine ( a Carnot heat engine) operating between the same high temperature and low temperature reservoirs. The efficiencies of all reversible engines ( Carnot heat engines) operating between the same constant temperature reservoirs are ...
How to approximate a reversible process?
One way to make real processes approximate reversible process is to carry out the process in a series of small or infinitesimal steps or infinitely slowly, so that the process can be considered as a series of equilibrium states.
Why do heat engines have lower efficiencies than limits?
Therefore, heat engines must have lower efficiencies than limits on their efficiency due to the inherent irreversibility of the heat engine cycle they use. However, for analysis purposes, one uses reversible processes to make the analysis simpler, and to determine maximum thermal efficiencies. For example the Carnot cycle is considered as ...
Why is it not possible to have a perfectly reversible process?
A perfectly reversible process is not possible in reality because it would require an infinite time and infinitesamally small steps. Although not practical for real processes, this method is beneficial for thermodynamic studies since the rate at which processes occur is not important.
Is the Carnot cycle reversible?
For example the Carnot cycle is considered as a cycle that consist of reversible processes: Since the cycle is reversible, there is no increase in entropy during the cycle and entropy is conserved. During the cycle, an arbitrary amount of entropy Δ S is extracted from the hot reservoir, and deposited in the cold reservoir.
Is thermodynamic equilibrium irreversible?
During reversible process the entropy of the system does not increase and the system is in thermodynamic equilibrium with its surroundings. In reality, there are no truly reversible processes. All real thermodynamic processes are somehow irreversible. They are not done infinitely slowly.
Overview
In science, a process that is not reversible is called irreversible. This concept arises frequently in thermodynamics. All complex natural processes are irreversible, although a phase transition at the coexistence temperature (e.g. melting of ice cubes in water) is well approximated as reversible.
In thermodynamics, a change in the thermodynamic state of a system and all o…
Absolute versus statistical reversibility
Thermodynamics defines the statistical behaviour of large numbers of entities, whose exact behavior is given by more specific laws. While the fundamental theoretical laws of physics are all time-reversible, experimentally the probability of real reversibility is low and the former state of system and surroundings is recovered only to certain extent (see: uncertainty principle). The reversibility of thermodynamics must be statistical in nature; that is, it must be merely highly unli…
History
The German physicist Rudolf Clausius, in the 1850s, was the first to mathematically quantify the discovery of irreversibility in nature through his introduction of the concept of entropy. In his 1854 memoir "On a Modified Form of the Second Fundamental Theorem in the Mechanical Theory of Heat," Clausius states:
Examples of irreversible processes
In the physical realm, many irreversible processes are present to which the inability to achieve 100% efficiency in energy transfer can be attributed. The following is a list of spontaneous events which contribute to the irreversibility of processes.
• Ageing (this claim is disputed, as aging has been demonstrated to be reversed in mice. NAD+ and telomerase have also been demonstrated to reverse ageing.)
Complex systems
The difference between reversible and irreversible events has particular explanatory value in complex systems (such as living organisms, or ecosystems). According to the biologists Humberto Maturana and Francisco Varela, living organisms are characterized by autopoiesis, which enables their continued existence. More primitive forms of self-organizing systems have been described by the physicist and chemist Ilya Prigogine. In the context of complex systems, events which lead t…
See also
• Entropy production
• Entropy (arrow of time)
• Exergy
• Reversible process (thermodynamics)
• One way function