Isothermal

Definition

An isothermal process is a thermodynamic process in which the temperature of the system remains constant. Heat transfer occurs to maintain this constant temperature.

5 Must Know Facts For Your Next Test

1. In an isothermal process, the internal energy of an ideal gas remains unchanged because it depends only on temperature.
2. The work done by or on the system can be calculated using $W = nRT \ln(\frac{V_f}{V_i})$ for an ideal gas, where $n$ is the number of moles, $R$ is the gas constant, and $V_f$ and $V_i$ are final and initial volumes respectively.
3. Isothermal processes require slow changes to allow heat exchange with surroundings to maintain constant temperature.
4. In an isothermal expansion, the system absorbs heat (Q) from its surroundings.
5. During an isothermal compression, the system releases heat (Q) to its surroundings.

Review Questions

• What remains constant in an isothermal process?
• How do you calculate work done during an isothermal expansion for an ideal gas?
• Why must changes occur slowly in an isothermal process?

Related terms

Adiabatic: A thermodynamic process in which no heat transfer occurs into or out of the system.

Isobaric: A thermodynamic process that occurs at a constant pressure.

Isochoric: A thermodynamic process that occurs at a constant volume.