# Thermodynamics - work in adiabatic, isothermal, isobaric

In summary, the three processes in order of the work required of an external agent, from least to greatest, are A. adiabatic, isothermal, isobaric. This is because the work done by the external agent is positive in these processes, with adiabatic having the smallest area enclosed under the curve, followed by isothermal, and then isobaric.

## Homework Statement

21. A quantity of an ideal gas is compressed to half its initial volume. The process may be adiabatic, isothermal, or isobaric. Rank those three processes in order of the work required of an external agent, least to greatest.

## The Attempt at a Solution

If I graph these three curves on a P-V axes, it seems to me that the work by the external agent will be positive because the volume is getting smaller. Also, the work is like the area under the curve for any of these processes, and so I get it choice A as my answer.

The isobaric path encloses a rectangle, the isothermal a hyperbola and the adiabat, a path that encloses less area than the isothermal.

I'm only checking because the answer given is E. And I don't know where I'm going wrong.

Thanks a lot ahead of time.

The problem lies in what you treat external work as. The most accepted convention-well at least in my part of the world-is that work energy coming in the system is negative hence the inequality you built would be reversed.Your logic seems good enough.

## What is the definition of adiabatic work in thermodynamics?

Adiabatic work in thermodynamics refers to work done by or on a system that occurs without any heat transfer. This means that the change in internal energy of the system is solely due to work being done on or by the system.

## How does adiabatic work differ from isothermal work?

The main difference between adiabatic and isothermal work is that adiabatic work occurs without any heat transfer, while isothermal work occurs at a constant temperature. In adiabatic work, the change in internal energy is due to work alone, while in isothermal work, the change in internal energy is due to both work and heat transfer.

## What is the significance of isobaric work in thermodynamics?

Isobaric work refers to work done at a constant pressure. This type of work is important because it allows us to calculate the change in enthalpy of a system, which is a measure of the total energy of the system.

## How does work in adiabatic, isothermal, and isobaric processes affect the internal energy of a system?

In adiabatic processes, the change in internal energy is solely due to work being done on or by the system. In isothermal processes, the change in internal energy is due to both work and heat transfer. In isobaric processes, the change in internal energy is also due to both work and heat transfer, but the pressure remains constant.

## Can work be reversed in thermodynamics?

According to the second law of thermodynamics, work can only be completely reversed in a reversible process. In irreversible processes, some of the energy is lost as heat, making it impossible to fully reverse the work done. Therefore, work in thermodynamics is generally considered irreversible.

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