Thermodynamics concept question

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Homework Help Overview

The discussion revolves around the thermodynamic concept of why an ideal gas cools during adiabatic and reversible expansion. Participants explore the relationship between gas expansion, internal energy, and temperature changes.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the mechanics of gas expansion and its effects on internal energy and temperature. Questions arise about the relationship between work done by the gas and energy loss, as well as the implications of adiabatic conditions.

Discussion Status

The conversation is ongoing, with some participants expressing uncertainty about the concepts. There are indications that guidance has been offered regarding the connection between internal energy and temperature, but no consensus has been reached.

Contextual Notes

Participants are navigating the implications of adiabatic processes and the assumptions related to energy transfer and temperature changes in gases.

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Problem: Why does an ideal gas cool when it expands adiabatically and reversibly?

Is the volume of the container expanding? so the total kinetic energy of the gas is getting smaller as it occupies more space making the temperature cool?
 
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The gas does work in order to expand. This work is done at the expense of the internal energy of the gas. (KE of its molecules)
 
Is that all? so when the gas is doing work, it will loose energy? is that because the system is loosing energy and the temperature willl decrease??
 
still unsure...
 
The gas does work.
The energy to do this comes from the internal energy of the gas.
The temperature of the gas depends on the (average) KE of the molecules.
If internal energy is lost, KE is reduced, temperature goes down.
(Because its adiabatic, no heat energy is allowed into the gas from outside.
If it was allowed, this heat energy would appear as internal energy and cause the temperature to rise.)
 

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