Reversible and Irreversible Processes

You often do not acknowledge several physical, chemical and other changes happening around you. Some of these processes cannot even be felt, with their existence often eluding you. However, these processes do occur and there is a difference in the state of the participants taking part in these processes. 

For instance, boiling of water, melting of ice, burning of things, etc. All these are processes that are distinct in nature, although, in all of them, one aspect is common. There is an exchange of heat or energy in each case, and they can be classified under reversible and irreversible processes. 

What is a Reversible Process?

A reversible process is the process where  it never occurs; on the contrary the irreversible process is the one which can be said to be the natural process and cannot be reversed.

For example water changing into water vapor is a reversible process whereas tearing the page is an irreversible process. This is because can we tear the pages? No we cannot so the process cannot be reversed.

Thermodynamics is the example of the reversible process. Here the system and the surroundings return to the same stage at the end of the process.

Students should note that a reversible process takes two processes into account. While in the first process participants convert into another form, in the case of this second process the reverse reaction takes place where the resultants get back to the initial stage.

Hence, understanding this will help in further delving into the difference between reversible and irreversible processes. You should also note that understanding these processes is not just vital for your Physics curriculum, but also that of chemistry.

Types of Reversible Processes

There are two types of reversible processes. The internally reversible process and the external reversible process.

• Internal reversible process involves no irreversibilities within the system boundaries. This states that the system undergoes the stage of equilibrium but when it returns it again passes through the sme stage.

In other words we can define a reversible process in simple words that the process that can be reversed completely.

• In the externally reversible process there are no irreversibilities. For example we can say about reservoirs and the system.

What is an Irreversible Process?

To understand this, consider a reversible process example - the cooking of food. You begin by arranging the necessary ingredients - vegetables, spices and meat and cook the entire thing and prepare a dish. Now, however hard you try, you cannot get back the ingredients in their original form. Another fine example is that of fuel consumption where once converted into energy, the process cannot be reversed to get back the fuel.

They have already been turned into something new which possess a completely different set of properties. Yet another crucial aspect that comes here is that the participants lose their individual characteristics in an irreversible process. 

Therefore, students should be cautious while studying both reversible processes and irreversible processes. Each process or method should be carefully analyzed so as to understand its type. 

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. 

Students should be able to tell the difference between reversible and irreversible processes in thermodynamics only when they have built an understanding of the same. 

Factors behind Irreversibility of a Process

A reversible process has certain consciousness if the procedure has to be undergone.

• There should be absence of the dissipative force and the second condition is that the process should be in a small time.

On the other hand, an irreversible process can be said to be the thermodynamics process that departs equilibrium.

When we talk in terms of pressure we can say that it occurs when the pressure of the system changes and the volume does not have time to reach equilibrium.

One of the points to note is that the system and the surrounding does not come back to the original state even after the completion of the process in the spontaneous process.

The Reversible Nature of a Process is Dependent on Multiple Factors Such as -

• Non-elasticity

• Friction

• Viscosity

• Electrical resistance

• Magnetic resistance or hysteresis

As a student, it is important you have an idea of the various criteria for reversible and irreversible processes. 

To know more about what is a reversible and irreversible process, check our online learning programmes for an in-depth understanding. You will get access to high quality lessons that will help you in building these vital concepts from their grassroot level.

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